EMBRYOPSIDA Pirani & Prado
Gametophyte dominant, independent, multicellular, initially ±globular, not motile, branched; showing gravitropism; glycolate oxidase +, glycolate metabolism in leaf peroxisomes [glyoxysomes], acquisition of phenylalanine lysase* [PAL], flavonoid synthesis*, microbial terpene synthase-like genes +, triterpenoids produced by CYP716 enzymes, CYP73 and phenylpropanoid metabolism [development of phenolic network], xyloglucans in primary cell wall, side chains charged; plant poikilohydrous [protoplasm dessication tolerant], ectohydrous [free water outside plant physiologically important]; thalloid, leafy, with single-celled apical meristem, tissues little differentiated, rhizoids +, unicellular; chloroplasts several per cell, pyrenoids 0; centrioles/centrosomes in vegetative cells 0, microtubules with γ-tubulin along their lengths [?here], interphase microtubules form hoop-like system; metaphase spindle anastral, predictive preprophase band + [with microtubules and F-actin; where new cell wall will form], phragmoplast + [cell wall deposition centrifugal, from around the anaphase spindle], plasmodesmata +; antheridia and archegonia +, jacketed*, surficial; blepharoplast +, centrioles develop de novo, bicentriole pair coaxial, separate at midpoint, centrioles rotate, associated with basal bodies of cilia, multilayered structure + [4 layers: L1, L4, tubules; L2, L3, short vertical lamellae] (0), spline + [tubules from L1 encircling spermatid], basal body 200-250 nm long, associated with amorphous electron-dense material, microtubules in basal end lacking symmetry, stellate array of filaments in transition zone extended, axonemal cap 0 [microtubules disorganized at apex of cilium]; male gametes [spermatozoids] with a left-handed coil, cilia 2, lateral, asymmetrical; oogamy; sporophyte +*, multicellular, growth 3-dimensional*, cuticle +*, plane of first cell division transverse [with respect to long axis of archegonium/embryo sac], sporangium and upper part of seta developing from epibasal cell [towards the archegonial neck, exoscopic], with at least transient apical cell [?level], initially surrounded by and dependent on gametophyte, placental transfer cells +, in both sporophyte and gametophyte, wall ingrowths develop early; suspensor/foot +, cells at foot tip somewhat haustorial; sporangium +, single, terminal, dehiscence longitudinal; meiosis sporic, monoplastidic, MTOC [= MicroTubule Organizing Centre] associated with plastid, sporocytes 4-lobed, cytokinesis simultaneous, preceding nuclear division, quadripolar microtubule system +; wall development both centripetal and centrifugal, 1000 spores/sporangium, sporopollenin in the spore wall* laid down in association with trilamellar layers [white-line centred lamellae; tripartite lamellae]; plastid transmission maternal; nuclear genome [1C] <1.4 pg, main telomere sequence motif TTTAGGG, KNOX1 and KNOX2 [duplication] and LEAFY genes present, ethylene involved in cell elongation; chloroplast genome with close association between trnLUAA and trnFGAA genes [precursors for starch synthesis], tufA, minD, minE genes moved to nucleus; mitochondrial trnS(gcu) and trnN(guu) genes +.
Many of the bolded characters in the characterization above are apomorphies of more or less inclusive clades of streptophytes along the lineage leading to the embryophytes, not apomorphies of crown-group embryophytes per se.
All groups below are crown groups, nearly all are extant. Characters mentioned are those of the immediate common ancestor of the group,  contains explanatory material, () features common in clade, exact status unclear.
Sporophyte well developed, branched, branching dichotomous, potentially indeterminate; hydroids +; stomata on stem; sporangia several, terminal; spore walls not multilamellate [?here].
II. TRACHEOPHYTA / VASCULAR PLANTS
Sporophyte long lived, cells polyplastidic, photosynthetic red light response, stomata open in response to blue light; plant homoiohydrous [water content of protoplasm relatively stable]; control of leaf hydration passive; plant endohydrous [physiologically important free water inside plant]; PIN[auxin efflux facilitators]-mediated polar auxin transport; (condensed or nonhydrolyzable tannins/proanthocyanidins +); borate cross-linked rhamnogalactan II, xyloglucans with side chains uncharged [?level], in secondary walls of vascular and mechanical tissue; lignins +; roots +, often ≤1 mm across, root hairs and root cap +; stem apex multicellular [several apical initials, no tunica], with cytohistochemical zonation, plasmodesmata formation based on cell lineage; vascular development acropetal, tracheids +, in both protoxylem and metaxylem, G- and S-types; sieve cells + [nucleus degenerating]; endodermis +; stomata numerous, involved in gas exchange; leaves +, vascularized, spirally arranged, blades with mean venation density ca 1.8 mm/mm2 [to 5 mm/mm2], all epidermal cells with chloroplasts; sporangia in strobili, sporangia adaxial, columella 0; tapetum glandular; sporophyte-gametophyte junction lacking dead gametophytic cells, mucilage, ?position of transfer cells; MTOCs not associated with plastids, basal body 350-550 nm long, stellate array in transition region initially joining microtubule triplets; archegonia embedded/sunken [only neck protruding]; embryo suspensor +, shoot apex developing away from micropyle/archegonial neck [from hypobasal cell, endoscopic], root lateral with respect to the longitudinal axis of the embryo [plant homorhizic].[MONILOPHYTA + LIGNOPHYTA]
Sporophyte growth ± monopodial, branching spiral; roots endomycorrhizal [with Glomeromycota], lateral roots +, endogenous; G-type tracheids +, with scalariform-bordered pits; leaves with apical/marginal growth, venation development basipetal, growth determinate; sporangium dehiscence by a single longitudinal slit; cells polyplastidic, MTOCs diffuse, perinuclear, migratory; blepharoplasts +, paired, with electron-dense material, centrioles on periphery, male gametes multiciliate; nuclear genome [1C] 7.6-10 pg [mode]; chloroplast long single copy ca 30kb inversion [from psbM to ycf2]; mitochondrion with loss of 4 genes, absence of numerous group II introns; LITTLE ZIPPER proteins.
Sporophyte woody; stem branching axillary, buds exogenous; lateral root origin from the pericycle; cork cambium + [producing cork abaxially], vascular cambium bifacial [producing phloem abaxially and xylem adaxially].
SEED PLANTS† / SPERMATOPHYTA†
Growth of plant bipolar [plumule/stem and radicle/root independent, roots positively geotropic]; plants heterosporous; megasporangium surrounded by cupule [i.e. = unitegmic ovule, cupule = integument]; pollen lands on ovule; megaspore germination endosporic, female gametophyte initially retained on the plant, free-nuclear/syncytial to start with, walls then coming to surround the individual nuclei, process proceeding centripetally.
EXTANT SEED PLANTS
Plant evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); microbial terpene synthase-like genes 0; primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignin chains started by monolignol dimerization [resinols common], particularly with guaiacyl and p-hydroxyphenyl [G + H] units [sinapyl units uncommon, no Maüle reaction]; roots often ≥1 mm across, stele diarch to pentarch, xylem and phloem originating on alternating radii, cork cambium deep seated, gravitropism response fast; stem apical meristem complex [with quiescent centre, etc.], plasmodesma density in SAM 1.6-6.2[mean]/μm2 [interface-specific plasmodesmatal network]; eustele +, protoxylem endarch, endodermis 0; wood homoxylous, tracheids and rays alone, tracheid/tracheid pits circular, bordered; mature sieve tube/cell lacking functioning nucleus, sieve tube plastids with starch grains; phloem fibres +; cork cambium superficial; leaf nodes 1:1, a single trace leaving the vascular sympodium; leaf vascular bundles amphicribral; guard cells the only epidermal cells with chloroplasts, stomatal pore with active opening in response to leaf hydration, control by abscisic acid, metabolic regulation of water use efficiency, etc.; branching by axillary buds, exogenous; prophylls two, lateral; leaves with petiole and lamina, development basipetal, lamina simple; sporangia borne on sporophylls; spores not dormant; microsporophylls aggregated in indeterminate cones/strobili; grains monosulcate, aperture in ana- position [distal], primexine + [involved in exine pattern formation with deposition of sporopollenin from tapetum there], exine and intine homogeneous, exine alveolar/honeycomb; ovules with parietal tissue [= crassinucellate], megaspore tetrad linear, functional megaspore single, chalazal, sporopollenin 0; gametophyte ± wholly dependent on sporophyte, development initially endosporic [apical cell 0, rhizoids 0, etc.]; male gametophyte with tube developing from distal end of grain, male gametes two, developing after pollination, with cell walls; embryo cellular ab initio, suspensor short-minute, embryonic axis straight [shoot and root at opposite ends], primary root/radicle produces taproot [= allorhizic], cotyledons 2; embryo ± dormant; chloroplast ycf2 gene in inverted repeat, trans splicing of five mitochondrial group II introns, rpl6 gene absent; ??whole nuclear genome duplication [ζ/zeta duplication event], 2C genome size (0.71-)1.99(-5.49) pg, two copies of LEAFY gene, PHY gene duplications [three - [BP [A/N + C/O]] - copies], 5.8S and 5S rDNA in separate clusters.
IID. ANGIOSPERMAE / MAGNOLIOPHYTA
Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, apigenin and/or luteolin scattered, [cyanogenesis in ANA grade?], lignin also with syringyl units common [G + S lignin, positive Maüle reaction - syringyl:guaiacyl ratio more than 2-2.5:1], hemicelluloses as xyloglucans; root cap meristem closed (open); pith relatively inconspicuous, lateral roots initiated immediately to the side of [when diarch] or opposite xylem poles; epidermis probably originating from inner layer of root cap, trichoblasts [differentiated root hair-forming cells] 0, hypodermis suberised and with Casparian strip [= exodermis]; shoot apex with tunica-corpus construction, tunica 2-layered; starch grains simple; primary cell wall mostly with pectic polysaccharides, poor in mannans; tracheid:tracheid [end wall] plates with scalariform pitting, multiseriate rays +, wood parenchyma +; sieve tubes enucleate, sieve plates with pores (0.1-)0.5-10< µm across, cytoplasm with P-proteins, not occluding pores of plate, companion cell and sieve tube from same mother cell; ?phloem loading/sugar transport; nodes 1:?; dark reversal Pfr → Pr; protoplasm dessication tolerant [plant poikilohydric]; stomata randomly oriented, brachyparacytic [ends of subsidiary cells ± level with ends of guard cells], outer stomatal ledges producing vestibule, reduction in stomatal conductance with increasing CO2 concentration; lamina formed from the primordial leaf apex, margins toothed, development of venation acropetal, overall growth ± diffuse, secondary veins pinnate, fine venation hierarchical-reticulate, (1.7-)4.1(-5.7) mm/mm2, vein endings free; flowers perfect, pedicellate, ± haplomorphic, protogynous; parts free, numbers variable, development centripetal; P = T, petal-like, each with a single trace, outer members not sharply differentiated from the others, not enclosing the floral bud; A many, filament not sharply distinguished from anther, stout, broad, with a single trace, anther introrse, tetrasporangiate, sporangia in two groups of two [dithecal], each theca dehiscing longitudinally by a common slit, ± embedded in the filament, walls with at least outer secondary parietal cells dividing, endothecium +, cells elongated at right angles to long axis of anther; tapetal cells binucleate; microspore mother cells in a block, microsporogenesis successive, walls developing by centripetal furrowing; pollen subspherical, tectum continuous or microperforate, ektexine columellate, endexine restricted to the apertural regions, thin, compact, intine in apertural areas thick, orbicules +, pollenkitt +; nectary 0; carpels present, superior, free, several, spiral, ascidiate [postgenital occlusion by secretion], stylulus at most short [shorter than ovary], hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, carinal, dry; suprastylar extragynoecial compitum +; ovules few [?1]/carpel, marginal, anatropous, bitegmic, micropyle endostomal, outer integument 2-3 cells across, often largely subdermal in origin, inner integument 2-3 cells across, often dermal in origin, parietal tissue 1-3 cells across, nucellar cap?; megasporocyte single, hypodermal, functional megaspore lacking cuticle; female gametophyte lacking chlorophyll, four-celled [one module, egg and polar nuclei sisters]; ovule not increasing in size between pollination and fertilization; pollen grains bicellular at dispersal, germinating in less than 3 hours, siphonogamy, pollen tube unbranched, growing towards the ovule, between cells, growth rate (ca 10-)80-20,000 µm h-1, tube apex of pectins, wall with callose, lumen with callose plugs, penetration of ovules via micropyle [porogamous], whole process takes ca 18 hours, distance to first ovule 1.1-2.1 mm; male gametophytes tricellular, gametes 2, lacking cell walls, ciliae 0, double fertilization +, ovules aborting unless fertilized; fruit indehiscent, P deciduous; mature seed much larger than fertilized ovule, small [<5 mm long], dry [no sarcotesta], exotestal; endosperm +, ?diploid [one polar nucleus + male gamete], cellular, development heteropolar [first division oblique, micropylar end initially with a single large cell, divisions uniseriate, chalazal cell smaller, divisions in several planes], copious, oily and/or proteinaceous, embryo short [<¼ length of seed]; plastid and mitochondrial transmission maternal; Arabidopsis-type telomeres [(TTTAGGG)n]; nuclear genome [2C] (0.57-)1.45(-3.71) [1 pg = 109 base pairs], ??whole nuclear genome duplication [ε/epsilon event]; ndhB gene 21 codons enlarged at the 5' end, single copy of LEAFY and RPB2 gene, knox genes extensively duplicated [A1-A4], AP1/FUL gene, palaeo AP3 and PI genes [paralogous B-class genes] +, with "DEAER" motif, SEP3/LOFSEP and three copies of the PHY gene, [PHYB [PHYA + PHYC]]; chloroplast IR expansions, chlB, -L, -N, trnP-GGG genes 0.
[NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]]: wood fibres +; axial parenchyma diffuse or diffuse-in-aggregates; pollen monosulcate [anasulcate], tectum reticulate-perforate [here?]; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.
[AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: phloem loading passive, via symplast, plasmodesmata numerous; vessel elements with scalariform perforation plates in primary xylem; essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood + [reaction wood: with gelatinous fibres, G-fibres, on adaxial side of branch/stem junction]; anther wall with outer secondary parietal cell layer dividing; tectum reticulate; nucellar cap + [character lost where in eudicots?]; 12BP [4 amino acids] deletion in P1 gene.
[[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]] / MESANGIOSPERMAE: benzylisoquinoline alkaloids +; sesquiterpene synthase subfamily a [TPS-a] [?level], polyacetate derived anthraquinones + [?level]; outer epidermal walls of root elongation zone with cellulose fibrils oriented transverse to root axis; P more or less whorled, 3-merous [?here]; pollen tube growth intra-gynoecial; extragynoecial compitum 0; carpels plicate [?here]; embryo sac monosporic [spore chalazal], 8-celled, bipolar [Polygonum type], antipodal cells persisting; endosperm triploid.
[MONOCOTS [CERATOPHYLLALES + EUDICOTS]]: (veins in lamina often 7-17 mm/mm2 or more [mean for eudicots 8.0]); (stamens opposite [two whorls of] P); (pollen tube growth fast).
[CERATOPHYLLALES + EUDICOTS]: ethereal oils 0 [or next node up]; fruit dry [very labile].
EUDICOTS: (Myricetin +), asarone 0 [unknown in some groups, + in some asterids]; root epidermis derived from root cap [?Buxaceae, etc.]; (vessel elements with simple perforation plates in primary xylem); nodes 3:3; stomata anomocytic; flowers (dimerous), cyclic; protandry common; K/outer P members with three traces, ("C" +, with a single trace); A ?, filaments fairly slender, anthers basifixed; microsporogenesis simultaneous, pollen tricolpate, apertures in pairs at six points of the young tetrad [Fischer's rule], cleavage centripetal, wall with endexine; G with complete postgenital fusion, stylulus/style solid [?here], short [<2 x length of ovary]; seed coat?; palaeotetraploidy event.
[PROTEALES [TROCHODENDRALES [BUXALES + CORE EUDICOTS]]]: (axial/receptacular nectary +).
[TROCHODENDRALES [BUXALES + CORE EUDICOTS]]: benzylisoquinoline alkaloids 0; euAP3 + TM6 genes [duplication of paleoAP3 gene: B class], mitochondrial rps2 gene lost.
[BUXALES + CORE EUDICOTS]: mitochondrial rps11 gene lost.
CORE EUDICOTS / GUNNERIDAE: (ellagic and gallic acids +); leaf margins serrate; compitum + [one position]; micropyle?; γ genome duplication [allopolyploidy, 4x x 2x], x = 3 x 7 = 21, 2C genome size (0.79-)1.05(-1.41) pg, PI-dB motif +; small deletion in the 18S ribosomal DNA common.
[ROSIDS ET AL. + ASTERIDS ET AL.] / PENTAPETALAE / [SANTALALES, CARYOPHYLLALES, SAXIFRAGALES, DILLENIALES, VITALES, ROSIDAE, [BERBERIDOPSIDALES + ASTERIDAE]: root apical meristem closed; (cyanogenesis also via [iso]leucine, valine and phenylalanine pathways); flowers rather stereotyped: 5-merous, parts whorled; P = K + C, K enclosing the flower in bud, with three or more traces, odd K adaxial, C with single trace; A = 2x K/C, in two whorls, alternating, (many, but then usually fasciculate and/or centrifugal); pollen tricolporate; G [(3, 4) 5], when 5 opposite K, whorled, placentation axile, style +, stigma not decurrent, compitum + [one position]; endosperm nuclear/coenocytic; fruit dry, dehiscent, loculicidal [when a capsule]; floral nectaries with CRABSCLAW expression, RNase-based gametophytic incompatibility system present.
[DILLENIALES [SAXIFRAGALES + ROSIDS]]: stipules + [usually apparently inserted on the stem].
[SAXIFRAGALES + ROSIDS] / ROSANAE Takhtajan / SUPERROSIDAE: ??
ROSIDS / ROSIDAE: anthers ± dorsifixed, transition to filament narrow, connective thin.
[ROSID I + ROSID II]: (mucilage cells with thickened inner periclinal walls and distinct cytoplasm); if nectary +, usu. receptacular; embryo long; chloroplast infA gene defunct, mitochondrial coxII.i3 intron 0.
ROSID II / MALVIDAE / [[GERANIALES + MYRTALES] [CROSSOSOMATALES [PICRAMNIALES [SAPINDALES [HUERTEALES [MALVALES + BRASSICALES]]]]]]: ?
[GERANIALES + MYRTALES]: ellagic acid +; K persistent in fruit.
Phylogeny. See the Dilleniales page for major patterns of relationships within Pentapetalae and the superrosid node for major patterns of relationships within the rosids, particularly the relationships of Geraniales and Myrtales.
MYRTALES Reichenbach - Main Tree.
Bark flaky; flavonols only, myricetin, methylated ellagic acid +; vessel elements?, vestured pits +, (rays with multiseriate part no wider than uniseriate part); tension wood +; secondary phloem stratified; (interxylary phloem +), internal phloem + [= intraxylary phloem, vascular bundles bicollateral]; cork cambium deep seated, (polyderm +); nodes 1:1; (vein endings with spirally-thickened tracheoids); cuticle waxes often 0; branching from current flush [all?]; leaves opposite, lamina with secondary veins joining an intramarginal vein [brochidodromous venation], margin entire, colleters + (?inc. = small stipuliform structures); inflorescence racemose; (flowers 4-merous); hypanthium +, nectariferous; K valvate, C clawed; filaments incurved in bud; pollen grains small [(40.94-)19.5-2(-9.93) μm long], ± spherical [see Kriebel et al. 2017], with pseudocolpi; ovary inferior, (transseptal bundles +), style long, minor stylar bundles +, stigma wet; ovules many/carpel, micropyle bistomal and zig-zag, inner integument ca 2 cells across; antipodal cells ephemeral; (mesotesta sclerotic), endotesta crystalliferous, exotegmen cells tracheidal; endosperm at most slight; x = 12. - 9 families, 380 genera, 13,005 species.
Includes Alzateaceae, Combretaceae, Crypteroniaceae, Lythraceae, Melastomataceae, Myrtaceae, Onagraceae, Penaeaceae, Vochysiaceae.
Note: In all node characterizations, boldface denotes a possible apomorphy, (....) denotes a feature the exact status of which in the clade is uncertain, [....] includes explanatory material; other text lists features found pretty much throughout the clade. Note that the precise node to which many characters, particularly the more cryptic ones, should be assigned is unclear. This is partly because homoplasy is very common, in addition, basic information for all too many characters is very incomplete, frequently coming from taxa well embedded in the clade of interest and so making the position of any putative apomorphy uncertain. Then there are the not-so-trivial issues of how character states are delimited and ancestral states are reconstructed (see above).
Age. Wikström et al. (2001: note topology) dated crown Myrtales to (83-)79, 75(-71) Ma, Hengchang Wang et al. (2009) to (89-)85, 78(-74) Ma, although a Bayesian relaxed clock estimate was as much as 99 Ma, Tank et al. (2015: Table S2) ca 86 Ma, and Bell et al. (2010: note topology) offered dates of (99-)89 Ma. Thornhill et al. (2012a, 2015) suggest several dates, but they are all clustered around (98-)93.3-91.6(-85.7) Ma; an age of ca 111 Ma was suggested by Sytsma et al. (2004), (118.8-)116.4(-113.7) Ma by Berger et al. (2015: topology), ca 90 Ma by Sytsma and Berger (2011), (130.9-)125.5(-120.3) Ma by Gonçalves et al. (2020a) and (114.2-)104.9(-88.0) Ma by X.-F. Zhang et al. (2021).
The oldest fossils assignable to Myrtales are some 65 Ma old (Crepet et al. 2004).
Evolution: Divergence & Distribution. Myrtales contain ca 6% core eudicot diversity (Magallón et al. 1999), and Magallón et al. (2018) suggested that there was an increase in the diversification rate at this node that they dated to (116.4-)105.5(-96.6) Ma.
Berger et al. (2015) discuss the biogeography and diversification of Myrtales in some detail, noting that most families were restricted to or most diverse in the southern hemisphere, ancestrally being in South America (Lythraceae, Melastomataceae, Onagraceae, Vochysiaceae) or Africa (the [Crypteroniaceae [Alzateaceae + Penaeaceae]] clade, Myrtaceae). Energetically costly elements of floral displays (e.g. large flowers) have evolved in parallel in Myrtales, and perhaps paradoxically low cost floral elements, e.g. small flowers, shallow flowers, show phylogenetic inertia (i.e. are plesiomorphic?) (Vasconcelos & Proença 2015).
Myrtales, but not including Combretaceae, have distinctively small seeds (Cornwell et al. 2014).
Several characters common in Myrtales may be apomorphies here. Raffinose and stachyose are common oligosaccharides in phloem exudate in Myrtaceae, Onagraceae, Lythraceae and Combretaceae, at least (Zimmermann & Ziegler 1975). Polyderm (alternating endodermal and parenchymatous layers laid down by a pericyclic meristem) is known from families like Onagraceae, Lythraceae, Myrtaceae, and probably Penaeaceae, at least (Mylius 1913). Wood fibres are usually non-septate (e.g. Combretaceae), but those of Lythraceae, at least, are septate. In roots of some aquatic Lythraceae, Melastomataceae, Myrtaceae and Onagraceae (and Euphorbiaceae and Fabaceae) there is a distinctive lacunate cork produced from a pericyclic cork cambium (Little & Stockey 2006), and there may also be lacunae in the stem polyderm produced in response to flooding (Lempe et al. 2001). The cork cambium is sometimes initiated in the superficial or mid-cortical position (e.g. Myrtaceae, Melastomataceae). Tracheoidal sclereids with spiral wall thickenings that are associated with the vein endings are known from Vochysiaceae, Lythraceae, Combretaceae, Melastomataceae, Alzateaceae and Penaeaceae (Sajo & Rudall 2002); their more general distribution needs to be checked. Since there is internal phloem, petiole and midrib bundles are often bicollateral; Carlquist (2013) noted the occurrence of interxylary phloem in some Combretaceae, Melastomataceae, Onagraceae and Lythraceae. Weberling (2000) notes that "true rudimentary stipules" occur in Myrtaceae and most myrtalean families; stipules, when they occur, are indeed generally small, often not vascularized, and are likely to be colleters (see also Carr & Carr 1966; LaFrankie 2010; da Silva et al. 2012).
In Myrtaceae the calyx and corolla originate at about the same time, while in Lythraceae and Onagraceae the calyx is visible considerably before the corolla (Mayr 1969); it will be interesting to know the general distribution of this feature. Many Myrtales, including some Myrtaceae, have notably narrow petal bases, i.e., they are close to being clawed; the definition and distribution of clawed petals in Myrtales may have to be amended, but I have provisionally put "clawed petals" as a feature of the whole clade. In those taxa that have filaments that are straight in bud, the filaments are usually short; the length of the style is correlated in part with the length of the hypanthial tube. Although "inferior ovary" is put as a feature for the whole order, there is a fair amount of variation in ovary position in families like Vochysiaceae, Myrtaceae and Melastomataceae, indeed, in some Vochysiaceae the ovary becomes superior during development, although starting off as inferior (Litt 1999; Litt & Stevenson 2003a). Distinctive winged fruits are found in Combretaceae and rarely in Oenothera, and even more distinctive fruits that open by the placenta breaking through the ovary wall occur throughout Cuphea (Lythraceae) and in some Sonerila (Melastomataceae). The basic chromosome number for the order may be x = 12 (S. A. Graham et al. 1993).
L. A. S. Johnson and Briggs (1985) provide a morphological phylogeny for the group. For the evolution of pollen shape and size, see Kriebel et al. (2017); they use characters that are continuous variables and analyze the measurements in a phylogenetic framework - one of the few examples of this approach.
Ecology & Physiology. Salt tolerance has evolved quite often in Myrtales, most notably in Combretaceae (12 spp.) Lythraceae (21 spp.) and Myrtaceae (47 spp.: Moray et al. 2015).
Plant-Animal Interactions. The host plants of the moth group Mimallonoidea-Mimallonidae, with some 290 species and restricted to the American tropics, are predominantly Myrtales (St Laurent et al. 2021), and there the caterpillars live inside shelters/cases ("sack bearers": St Laurent et al. 2021). Woody Myrtales, especially Combretaceae, are ancestrally hosts of Mimallonidae, and there may be connections between diversification in these two groups - but note the some 60 Ma stem of Mimallonidae, which have a crown-group age of a mere (48.5-)44.0(-39.7) Ma, which makes it difficult to know what their caterpillars originally ate (St Laurent et al. 2021; for the Myrtales phylogeny, etc., used here see Berger et al. 2016). Interestingly, sister to Mimallonoidea are Macroheterocera, which St Laurent et al. (2021) estimate as having >74,000 species, and they are external feeders - the two groups diverged perhaps (108.4-)105.2(-100.3) Ma.
Lycaenid caterpillars are quite commonly to be found on Myrtales, especially on Lythraceae, Myrtaceae, Melastomataceae and Combretaceae, and most of them are myrmecophilous (Fielder 1991, 1995).
Genes & Genomes. Plastome variation in the order is not very great, being mainly in size - thus the inverted repeat is 23,902-36,747 bp long (c.f. in part X.-F. Zhang et al. 2021). In most taxa the IR is around 26,000 bp long, but in Lythraceae it is only 23,000-25,000 bp long. Other variables include features such as exactly what genes are at the junctions of the various architectural features of the plastome, etc. (X.-F. Zhang et al. 2021).
Chemistry, Morphology, etc.. For further information, see Dahlgren and Thorne (1985: general; also other papers in Ann. Missouri Bot. Gard. 71(3). 1985), Weiss (1890) and van Tieghem (1891b), cork cambium position, Jansen et al. (2008), Carlquist (2017a) and Carlquist and Raven (2018: inc. vesturing spreading on to vessel walls - scattered), all vestured pits, Meylan and Butterfield (1978: wood anatomy), Lourteig (1965), Venkateswarlu and Prakash Rao (1971: wood anatomy), Beusekom-Osinga and Beusekom (1975: morphology etc. around Crypteroniaceae), van Vliet and Baas (1985: vegetative anatomy), Weberling (1988: inflorescence morphology), Ronse Decraene and Smets (1991b: polyandry), Mauritzon (1939a: embryology), Tobe (1989) and Tobe and Raven (1983a, 1985a, 1985b, 1987a, 1990), all embryology and ovule morphology (ordinal characters are mostly plesiomorphous), Boesewinkel and Venturelli (1987: ovule and seed), and Solt and Wurdack (1980) and Almeda (1997), both chromosome numbers.
Phylogeny. The position of Myrtales within the rosids was unstable in a rbcL analysis of all angiosperms (Hilu et al. 2003). However, there was some support for a position sister to all other rosids except Geraniales, Vitales and Saxifragales (Zhu et al. 2007), while Wang et al. (2009) suggested that is was sister to Geraniales, the combined group being sister to all other malvids. See also the Pentapetalae and Saxifragales pages for further discussion on the relationships of Myrtales.
Relationships within the order have been extensively studied by Conti et al. (1996, 1998, 1999, 2002), Sytsma et al. (1998, esp. 2004), Clausing and Renner (2001: Melastomataceae), Schönenberger and Conti (2001, 2003: esp. Penaeaceae area, etc.), Wilson et al. (2005: Myrtaceae s.l.), and X.-F. Zhang et al. (2021: no Crypteroniaceae, etc.), and the tree is based on these publications. The position of Combretaceae has been somewhat unclear (see also Maurin et al. 2010; M. Sun et al. 2016; Kriebel et al. 2017). However, at least some support for a position sister to [Onagraceae + Lythraceae] was found by Berger and Sytsma (2010), Bell et al. (2010), Soltis et al. (2011), H.-T. Li et al. (2019: 98% bootstrap), Gonçalves et al. (2020a), X.-F. Zhang et al. (2021), X. Wang et al. (2021) and H.-T. Li et al. (2021) - last three, plastome analyses; support in the last four was strong, even if the branch subtending the clade was short in some. On the other hand, Maurin et al. (2021: Angiosperms353 nuclear analyses) found thaat the position of Combretaceae was unclear, hence the basal tritomy below.
Anatomy (vestured pits), some morphological features (general leaf type and insertion) and molecular data all strongly suggest that Vochysiaceae are to be included in Myrtales. However, at first sight the distinctive monosymmetric spurred flowers of that family are quite unlike those of the rest of the order.
Synonymy: Melastomatineae J. Presl - Circaeales Martius, Combretales Berchtold & J. Presl, Epilobiales Martius, Henslowiales Martius, Lythrales Link, Melastomatales Berchtold & J. Presl, Memecylales Martius, Myrobalanales link, Oenotherales Bromhead, Onagrales Berchtold & J. Presl, Penaeales Lindley, Trapales J. Presl, Vochysiales Link - Myrtanae Takhtajan - Myrtopsida Bartling, Oenotheropsida Brongniart
[Combretaceae [Onagraceae + Myrtaceae]]: raffinose and stachyose common oligosaccharides in phloem exudate; interxylary phloem +; polyderm + [alternating endodermal and parenchymatous layers laid down by pericyclic meristem]; fibres with at most minutely bordered pits; petiole bundle arcuate; exotegmen fibrous.
Age. The age of this clade is estimated to be (128.7-)123.5(118.5) Ma by Gonçalves et al. (2020a), while X.-F. Zhang et al. (2021) suggested an age of (109.3-)96.2(-81.0) Ma.
COMBRETACEAE R. Brown, nom. cons. - Back to Myrtalestannins often not abundant, soluble oxalate accumulating; vessels grouped; fibres with at most minutely bordered pits; (flowers vertically monosymmetric); tapetal cells binucleate; (pollen at anthesis with starch); nucellus with starch grains, K persistent; starch grains in nucellus.
Evergreen, woody; 5-desoxyflavonoids, flavonoid sulphates +; (cork epidermal); vesturing spreading over inside of vessel [?level], fibres non-septate; sclereids +/0; mucilage ducts + [?level]; petiole bundle also annular (wing bundles +); hairs appressed, unicellular, thick walled, apex pointed, with basal compartment, 2-armed; stipules at most small; (plant monoecious); flowers 4-5(-8)-merous; A obdiplostemonous, inserted below or at the hypanthial apex; nectary annular; G [2-5(-8)], alternate with K or odd member abaxial, unilocular, placentation apical, stigma punctate; ovules 2/carpel, outer integument 2-5 cells across, inner integument 2-4 cells across, parietal tissue 5-10 cells across, nucellar cap to 8 cells across, ± pachychalazal, hypostase +, funicles long, usu. with obturator; megaspore mother cells several; fruit indehiscent, dry; seed single, large; (testa multiplicative), endotesta tracheidal or sclerotic, crystals ?0; embryo often green; x = 12 (?13), nuclear genome [1 C] (0.35-)3.817(-41.585) pg.
10 [list: to tribes]/500: 3 groups below. Largely tropical. [Photo - Flower, Flower, Fruit.]
Age. Crown Combretaceae are ca 46 Ma (Sytsma et al. 2004) 0r (106.5-)102.6(-98.9) Ma (Berger et al. 2015). Sytsma and Berger (2011) suggested that Strephonema diverged soon after the origin of stem Combretaceae at ca 90 Ma.
Fossils of Esgueiria, assigned to Combretaceae, are widespread in the Northern Hemisphere in Late Cretaceous deposits ca 90-70 Ma old. They seem to have inferior unilocular ovaries with apical placentation and glandular-peltate hairs (Friis et al. 1992, 2011), there is no hypanthium, of the eight stamens, five are in one whorl and three in another, the styles are more or less separate, and the surface of the unicellular hairs of the Japanese, but not the Portugese, material is distinctly rough (Takahashi et al. 1999). The nature of the nectary is unclear; in some specimens there are structures outside the androecium that have been interpreted as possible nectaries (Takahashi et al. 1999) - they would be unlike the nectaries in extant Combretaceae. The identity of these fossils should be confirmed - to be compared with Hydrangeaceae? Dilcherocarpus, from the Albian-Cenomanian of the Dakota Group, Kansas, and ca 100 Ma old, has been assigned to Combretaceae (Manchester & O'Leary 2010).
1. Strephonematoideae Engler & Diels
Trees; vesture elements globular; imperfect tracheary elements with bordered pits; internal phloem 0; stomata paracytic, accessory cells subdivided; lamina with closely parallel tertiary venation ± at right angles to the midrib, domatia marginal, revolute; pollen lacking pseudocolpi, only semitectate; G half inferior; ovules 2; fruit largely superior; cotyledons hemispherical, large, conduplicate; n = ?; germination hypogeal.
1/3. West Africa (map: from Jongkind 1995; Trop. Afr. Fl. Pl. Ecol. Distr. 1. 2003).
2. Combretoideae Beilschmied
(hairs also lepidote), (stalked glands +); (petiole with glands); (plant dioecious); inflorescence often spicate; (embryo sac tetrasporic, 16-nucleate); cotyledons flattened; nuclear genome [1 C] (6259-)2919(-1223) Mb.
13/500. Largely tropical (map: from van Steenis & van Balgooy 1966; Wickens 1976; Trop. Afr. Fl. Pl. Ecol. Distr. 1. 2003; FloraBase 2006; Stace 2010).
Age. The age of this clade was estimated to be some (103.6-)101.6(-100.5) Ma by Gonçalves et al. (2020a), however, X.-F. Zhang et al. (2021) estimated an age around 25 Ma, although with huge error bars - and an odd topology.
2a. Laguncularieae Engler & Diels
Trees or shrubs; leaves often amphistomatous, stomata cyclocytic/anomocytic; lamina (with glands); bracteoles ± adnate to G, large to small; flower (monosymmetric - Danseia); K with three traces; nectary also bilobed, inside hypanthium/± 0; ovules 2-20; fruits flattened, (winged by the bracteoles); cotyledons spirally folded/convolute; n = 13; germination hypogeal/epigeal.
4/8. Tropical, mangroves, also N. and N.E. Australia.
Age. Ricklefs et al. (2006: ?sampling) dated crown Laguncularieae to ca 23 Ma.
2b. Combreteae Engler
Trees or shrubs (lianes); included phloem + [= interxylary phloem]; (mucilage ducts - Terminalia); stomata anomocytic; lamina vernation conduplicate or supervolute, domatia pocket- or bowl-shaped; K with one trace, C (small/0); A (= and alternate with/opposite to K), (-15); stigma (capitate); (micropyle endostomal - Guiera), (parietal tissue ca 10 cells across, pachychalazal - Combretum coccineum); fruit ± winged, (drupaceous); (integuments multiplicative); (megaspore mother cells several); n = (7, 11)12-13.
5/490. Largely tropical. Combretum (255), Terminalia (190).
Age. This node is about 33 Ma (Berger et al. 2015).
Synonymy: Bucidaceae Sprengel, Myrobalanaceae Martinov, Sheadendraceae G. Bertolini, nom. invalid., Terminaliaceae Jaume Saint-Hilaire
Evolution: Divergence & Distribution. For the fossil record of winged fruits that can be assigned to Combretaceae, see Manchester and O'Leary (2010).
Diversification of most of the family is a Caenozoic phenomenon (Sytsma & Berger 2011), indeed, there was a significant shift in speciation rates in Combreteae, but when that occurred is unclear (Berger et al. 2015).
Ecology & Physiology. Lumnitzera and Laguncularia are mangrove taxa (see articles in Ann. Bot. 115(3). 2015; Suvarna Raju 2021: pollination); the radicle of Laguncularia appears during dispersal (Rabinowicz 1978), although the seeds of Lumnitzera at least, soon sink (Clarke et al. 2001). For more on the mangrove habitat, see Rhizophoraceae.
Seed Dispersal. The flattened and/or winged fruits of Combretaceae are often wind- or water dispersed, and Systma and Berger (2011) note substantial dispersal of the family in the Pacific.
Chemistry, Morphology, etc.. The islands of included phloem in Combretum are connected in a reticulating fashion along the stem (Robert et al. 2011); den Outer and van Veenendaal (1995) noted that this system was more important in the transport of assimilates that the phloem outside the xylem - and that it was interesting that these plants were shrubs or trees, not lianas where odd vascular construction is almost the norm. Keating (1985) describes the stomata as being paracytic while Dahgren and Thorne (1985) call them anomocytic; in any event, variation in stomatal morphology is extensive (Stace 1965; Tilney 2002).
There are hairs lining the ovary loculus walls in Combretum.
Some general information is taken from S. A. Graham (1964), Venkateswarlu and Prakash Rao (1971) and Jongkind (1995), both Strephonema, Tomlinson (1986), and Stace (2006, 2010: New World taxa); see also Verhoeven and van der Schijff (1974: anatomy, inc. root cork cambium), Eckert (1966: obdiplostemony), El Ghazali et al. (1998: pollen), and Mauritzon (1939a), Fagerlind (1941a) and Venkateswarlu (1952b), all embryology.
Phylogeny. Strephonema is likely to be sister to the rest of the family (e.g. Maurin et al. 2017, 2021). Lumnitzera and Laguncularia, both mangrove plants, are sister taxa, but Conocarpus, found in similar habitats, is not immediately related (Tan et al. 2002; Maurin et al. 2010, 2921); Maurin et al. (2017) had found that the three genera of Laguncularieae were paraphyletic at the base of Combretoideae, although support for that position was not strong and it has not been confirmed. Furthermore, M. Sun et al. (2016) suggested that Conocarpus was sister to the rest of the family, but yhis, too has not been confirmed; the genus is sister to Terminalia s.l. in Maurin et al. 2010, 2021), although otherwise relationships are as noted above. Maurin et al. (2010) in particular discuss details of relationships within the family, especially in the large genera Terminalia and Combretum while Maurin et al. (2017) clarify the limits of Terminalia; see also Maurin et al. (2021).
Classification. For generic limits, especially around Combretum, see Stace (2007), while Maurin et al. (2010) suggest that the limits of Terminalia, currently paraphyletic, be expanded; support values underpinning change in neither case are very high. Fot a classification down to subtribes, see Maurin et al. (2010).
[Onagraceae + Lythraceae]: tannins often not abundant, soluble oxalate accumulating; vessels grouped; petiole bundle arcuate; tapetal cells binucleate; (pollen at anthesis with starch); nucellus with starch grains, hypostase +; megaspore mother cells several; K persistent; x = 8.
Age. The two families are estimated to have separated at the end-Cenomanian ca 93 Ma (Sytsma et al. 2004) or earlier, around (115.8-)101(-84.5) ma (Gonçalves et al. 2020a), (109.1-)104.6(-100.2) Ma (Berger et al. 2015) and ca 107.3 Ma (Inglis & Calvacanti 2018), or somewhat later, about 72.2/68.2 Ma (Tank et al. 2015: Table S2), (80-)67, 63(-49) Ma (Bell et al. 2010), (71-)67, 57(-53) Ma (Wikström et al. (2001) or (108.9-)89.6(-81.0) Ma (X.-F. Zhang et al. 2021).
Evolution: Divergence & Distribution. For attempts to relate the development of the female gametophyte of Onagraceae to that of Lythraceae, see e.g. Mauritzon (1934e).
Chemistry, Morphology, etc.. Both Trapa and some species of Ludwigia are aquatics with distinctive floating rosettes of expanded leaves. Decodon is the only typically pentamerous genus in Lythraceae (S. A. Graham 2006), as is Ludwigia (Onagraceae). Since both may be sister to the rest of their respective families, working out where floral merosity changes on the tree becomes difficult. A number of Lythraceae, including Trapa, have capitate stigmas, and this could be another feature uniting the two families.
ONAGRACEAE Jussieu, nom. cons. - Back to Myrtales
Plants herbaceous; flavonoid sulphates +; phloem loading via intermediary cells [specialized companion cells with numerous plasmodesmata, raffinose etc. involved]; raphides +; leaves (spiral), lamina vernation ± flat to involute, margins toothed, stipuliform structures +; bracteoles often 0; C deciduous, ± clawed; anthers polysporangiate, versatile, filaments straight in bud; pollen grains relatively large [55.25 (25.58 S.D.) μm long], oblate, colpi short, wide, protruding, pseudocolpi 0, starchy, surface psilate [smooth], ektexine paracrystalline, beaded, endexine massive, electron-dense, tectum, columella, foot layer all 0,viscin threads + [attached proximally]; nectary on G/base of hypanthium; G = to & alternating with K, stigma capitate (± lobed); ovules with outer integument 2-5 cells across, inner integument 2(-3) cells across, (epistase +), parietal tissue ca 2(?-13 - Vesque) cells across, nucellar cap ca 2 cells across, hypostase +/0; micropylar megaspore functional, embryo sac 4-nucleate [Oenothera type]; fruit loculicidal, opening down the sides; exotestal inner walls thickened and lignified, (mesotestal cells thickened, ± sclerotic; endotegmic cells longitudinally elongated, "tanniniferous", inner walls thickened); endosperm nuclear/coenocytic, diploid; x = 10 (?8, ?7), nuclear genome [1 C] (0.031-)0.847(-23.474) pg/(3081-)1309(-147) Mb.
22 [list, to tribes]/656 - two subfamilies below. World-wide. Map: based on Raven (1963a, 1967), Meusel et al. (1978), Trop. Afr. Fl. Pl. Ecol. Distr. 1. (2003), also P. Hoch & W. Wagner (pers. comm.).
Age. Crown-group Onagraceae are estimated to be ca 82 Ma (Sytsma et al. 2004), (96.2-)85.4(-73.3) Ma (Berger et al. 2015), (88.4-)71(-54.3) Ma (Gonçalves et al. 2020a) or (74.1-)46.9(-2.7) Ma (X.-F. Zhang et al. 2021).
1. Jussiaeoideae Beilschmied
Herbs (annuals), (shrublets); stem with endodermis; flowers 4-5-merous; hypanthium 0; (A 10); pollen in tetrads (monads; large irregular clumps), colpi vertically elongated, columellae 0, viscin threads ± simple, smooth; G (3-)4-5(-7), with central vascular bundles, (style 0), minor stylar bundles +; nectary on top of ovary; ovules with parietal tissue 3-6 cells across, hypostase +; megasporocyte 1; capsule (apically porose); seed (chalaza expanded/= wing); much polyploidy.
1 (Ludwigia)/82: World-wide, esp. America, commonly moist habitats. [Photo - Flower.]
Synonymy: Isnardiaceae Martinov, Jussiaeaceae Martinov
2. Onagroideae Beilschmied
Included phloem +; flowers 4-merous, hypanthium long; K reflexed; pollen oblate, viscin threads usu. compound, variously beaded, twisted, etc.; transseptal vascular bundles + (0), minor stylar bundles 0, (stylar bundles 0), (stigma 4-lobed; dry); ovules (parietal tissue 10-25 cells across); hypanthium separating at base in fruit.
21/574. World-wide, but esp. western North America. [Photo - Flower, Flower.]
Age. This age of this node (Hauyeae + Circaeeae) is at least ca 52 Ma (Berry et al. 2004).
2a. Hauyeae Raimann
Shrubs to trees; leaves spiral; flowers axillary; pedicels short; pollen por(or)ate; seeds asymmetrically winged; n/x = 10.
1/2. Mexico (Hidalgo, Guerrero) to Costa Rica.
[Circaeeae [Lopezieae [Gongylocarpeae [Epilobieae + Onagreae]]]]: x = 11.
2b. Circaeeae Dumortier
Pollen columellae (±) 0; fruit indehiscent [very different types].
2/113. Northern Hemisphere, Mexico to the Andes, New Zealand, Tahiti.
Age. This node is at least ca 41 Ma (Berry et al. 2004).
Rhizomatous herb; hypanthium constricted/very short; flowers 2-merous; K 2, lateral, C 2, ± lobed; A 2, opposite K; pollen with smooth viscin threads; ovules 1/carpel; fruit indehiscent, dry, with uncinate hairs.
1/8. Northern Hemisphere.
Synonymy: Circaeaceae Berchtold & J. Presl
Plant woody (lianes/epiphytes/trees), (deciduous); flowers (axillary/sessile), protogynous; C (0); pollen grains 2 aperturate, colpi horizontally elongated; fruit baccate; seeds embedded in pulp (not).
1/105. Mexico to Tierra del Fuego, esp. the northern Andes, New Zealand, Tahiti.
Age. Crown-group Fuchsia is at least ca 31 Ma (Berry et al. 2004).
Synonymy: Fuchsiaceae Lilja
[Lopezieae [Gongylocarpeae [Epilobieae + Onagreae]]]: ?
2c. Lopezieae Spach
Leaves usu. spiral; flowers monosymmetric [very different types]; pollen grains [Lopezia] triangular in polar view, apertures rimmed porate.
2/23. Mexico to Central America.
Megacorax S. González & W. Wagner
Shrubs; leaves fasciculate, blades ± linear; C as presented monosymmetric; hypanthium very short; n/x = 15.
1/1: Megacorax gracielanus. Mexico (Durango).
(Annual) herbs/shrubs; (adaxial C pair auriculate/with glands); A 1 [abaxial] + 1 petaloid staminode [vertical pair]; pollen columellae 0 [?tribe]; seeds tuberculate; n = 7-11.
1/22. Mostly Mexico, to Panama.
Synonymy: Lopeziaceae Lilja
[Gongylocarpeae [Epilobieae + Onagreae]]: stipuliform structures 0.
2d. Gongylocarpeae Donnell Smith & Rose
Herbs, annual/shrubs; leaves spiral; flowers sessile; pollen porate, protrusions 0, viscin threads beaded; ovules 1/carpel, parietal tissue "thick"; fruit in pith of stem, indehiscent.
1/2. Mexico and Guatemala.
[Epilobieae + Onagreae]: leaves ± spiral; pollen (columellae 0).
Age. This clade may be ca 26 Ma (Landis et al. 2018: genome duplication).
2e. Epilobieae Endlicher
Annual/perennial herbs to subshrubs; (floral tube 0), (with scales towards base); K erect (spreading); pollen in tetrads, viscin threads often smooth; stigma dry, lobes commissural, papillae multicellular; parietal tissue 0; seeds with chalazal hairs (not); n = 9-10, 12-13, 15-16 [x = ?9].
2/173: Epilobium (165). Widely distributed, few in lowland tropics.
Synonymy: Epilobiaceae Ventenat
2f. Onagreae Dumortier
Anuual to perennial herbs (shrubs); lamina (deeply pinnately lobed); flowers (sessile), (hypanthium short); pollen (porate0, (protrusions notably prominent), (0), surface (beaded-linear), (viscin threads smooth - Clarkia); stigma (with basal indusium - Oenothera), (strongly lobed); (ovules to 1/carpel); (seeds winged); n (5-)7(-9) [x = 7], translocation rings/0, (plastid transmission biparental - Oenothera).
13/260: Oenothera (145), Clarkia (42). North and South America, especially western North America.
Synonymy: Oenotheraceae C. C. Robin
Evolution: Divergence & Distribution. For the fossil history of the family, see Grímsson et al. (2011a) and Lee et al. (2013) and references; the fossil pollen is very distinctive and is known from the Maastrichtian, at least 66 Ma. Pollen of Corsinipollenitis from Late Cretaceous sediments in India perhaps ca 66 Ma has been linked with a couple of Old World species of Ludwigia like L. perennis (Farooqui et al. 2019) that are quite closely related. Two other Indian species, L. adscendens and L. octovalvis, have been associated with Ludwigia pollen from Pleistocene deposits in India; these species are quite unrelated (see S.-H. Liu et al. 2017: phylogeny of Ludwigia). Corsinipollenitis has also been described from Palaeocene deposits in Venezuela (Pocknall & Jarzen 2009).
The apomorphy scheme above is based in part on that in Wagner et al. (2007), q.v. for more details about individual genera in particular.
Pollination Biology. For details of floral morphology in Onagraceae and its relation to pollination, see Wagner et al. (2007). Just about all the New World species of Fuchsia are likely to be pollinated by humming birds, and even species from New Zealand are pollinated by the local birds (e.g. Berry 1989; Wagner et al. 2007 and references). Pollination in North American members of the family has been studied in great detail (e.g. references in Linsley et al. 1973; Clinebell et al. 2004). The strongly monosymmetric flowers of Lopezia have only a single abaxial stamen that may become extrorse during explosive dehiscence and a petal-like adaxial staminode; the two adaxial petals may be recurved and have pseudonectaries on their claws (Eyde & Morgan 1973). Some 12 species of oligolectic Andrena bees are major visitors to Camissonia campestris alone (Linsley et al. 1973), while Clinebell et al. (2004) documented a wide variety of potential pollinators visiting the four species of Onagraceae and three other species that they studied. It has been suggested that plants of Oenothera drummondii can sense pollinators (by vibration), and that this caused a rapid increase in the sugar concentration of the nectar produced (Veits et al. 2018/2019); this must be confirmed, and in its native habitat. How petal spots develop in Clarkia gracilis has recently been worked out (Martins et al. 2012).
Protogyny is quite common in a few clades; the non-protogynous taxa are either protandrous or undecided in equal numbers (Newman 1993). For a general survey of reproductive biology in Onagraceae, see Raven (1979).
Plant-Animal Interactions. Some caterpillars are found on both Vitaceae and Onagraceae (Forbes 1956), both groups that contain raphides that have been suggested to deter feeding (Hyles lineata was defoliating Onagraceae - California 2019). Similarly, the gelechioid moth Momphis has diversified on Onagraceae, where various species eat flowers and fruits or are gallers or leaf miners, etc., and the moth is also found on raphide-bearing Rubiaceae, and a few species on other families including Melastomataceae - which may not have raphides but of course is also Myrtales (Bruzzese et al. 2019).
M. T. J. Johnson (2014) discussed proanthocyanidins, ellagitannins and caffeic acid derivatives, deterrents against herbivory, in Oenothera. Interestingly, the control of flavonoid biosynthesis is affected in permanent translocation heterozygotes (see below), which are functionally asexual, both flavonoids and attacks by generalist mites increasing (Johnson et al. 2009, 2014), although any connection between the principal components of variation in flavonoid defences and plant phylogeny was at most moderate (Johnson et al. 2014), as is common in such interactions (Cacho et al. 2015).
Bacterial/Fungal Associations. Rusts on Onagroideae and Jussiaeoideae differ (Savile 1979b).
Genes & Genomes. A genome duplication for the [Epilobeae + Onagreae] clade, the OEGRα event, has been dated to ca 26 Ma (Landis et al. 2018).
For general cytological studies, see Tanaka et al. (1988) and for chromosome numbers, see Wagner et al. (2007).
All the chromosomes in some species of Oenothera form a ring at meiosis being joined by a series of permanent translocations; the whole genome then forms a single linkage unit (Cleland 1972), and reproduction is effectively asexual. Golczyk et al. (2014) found that breaks occurred subterminally between between two distinct chromatin regions and that there were no normal telomeres; translocations did not involve whole arms. Although the permanent translocation heterozygotes/hybrids (PTH) self, they show increased diversification rates over sexual species, interestingly, there are frequent reversals from PTH to sexuality, and the PTH condition has arisen ca 20 times (M. T. J. Johnson et al. 2011). The whole system sometimes breaks down (see Harte 1993: the contributions of Oenothera to biology; Stubbe & Steiner 1999 and references: translocation, etc; Wagner et al. 2007).
Particular combinations of genome and plastome may be incompatible, and the resultant inviability of some of these combinations may provide genetic barriers between taxa (Stubbe & Steiner 1999). Incompatability between chloroplasts from one parent and the hybrid genome (plastome-genome incompatability - PGI) may result in the death of those chloroplasts and thus to variegation (Snijder et al. 2007; Ruhlman & Jansen 2018 and references). AB-I plants cannot acclimate to high-light intensities (Zupok et al. 2021). Chiu and Sears (1993 and references) discuss biparental transmission of plastids in Oenothera. Sobanski et al. (2019) looked at the control of plastid competition and inheritance (the accC and ycf2 genes are involved), and they suggested that aggressive plastomes were derived, having evolved twice in the genus (once with a reversal would also be possible?). There is basically no hybrid incompatability involving nuclear loci, and hybridization is widespread in the genus (references in Zupok et al. 2021). The American school recognises ca 13 species in the genus that are based on particular combinations of nuclear and chloroplast genomes, while in the largely morphological species definition of the European school ca 80 species are recognized... (Zupok et al. 2021).
Erixon and Oxelman (2008b) found elevated positive substitution rates in the clpP1 gene in Oenothera, and there was also a great increase in the size of some exons, loss of introns, etc..
Chemistry, Morphology, etc.. The morphology, anatomy, etc., of Onagraceae are rather better known the most comparable families thanks to extensive comparative studies carried out from the 1960s onwards by P. H. Raven and his associates.
The "stipules" of Ludwigia can be quite prominent.
The ovary of Gongylocarpus becomes completely enveloped by stem tissue after pollination (Carlquist & Raven 1966). Tobe and Raven (1986a) noted that the septae in the polysporangiate anthers of Onagraceae might be of tapetal or (largely) parenchymatous origin; the former was likely to be an apomorphzy for the family, and the latter morphology has been derived several times. The pollen grains of some species of Oenothera are very large indeed, triangular in polar view, and with strongly protruding pores (Kriebel et al. 2017). The viscin threads that characterize the family vary considerably in morphology, often being annular-vermiform, but they are also smooth or irregularly beaded (Skvarla et al. 1976). In Oenothera, more than one spore from the same megaspore mother cell may germinate and - presumably - compete (Noher de Halac & Harte 1977). Carlquist and Raven (1966) described seeds of Gongylocarpus fruticulosus that had elongated ?exo/mesotegmic cells with gelatinous wall thickenings running at right angles to elongated endotegmic cells with their ?tanniniferous contents.
For other information, see the Onagraceae website and Wagner et al. (2007: superb summary), both general, also Tobe and Raven (2018: vestured pits), Eyde (1982: floral anatomy), Maheshwari (1947), Tobe and Raven (1986b, 1987d, 1996) and Hoch et al. (1993: variation in anther septum development, embryology), Praglowski et al. (1983, 1987, 1989, 1994: pollen), Skvarla et al. (1977: tetrads, 1978: viscin threads), Johansen (1928: hypostase and environmental correlations), and Tobe et al. (1987d: seed coat anatomy).
Phylogeny. Ludwigia is sister to the rest of the family. Within Ludwigia, taxa with five and those with ten stamens form separate clades (Barber et al. 2008), although support for the 10-stamen clade was strong only in Bayesian analyses (S.-H. Liu et al. 2017). Support for relationships in the 5-stamen clade was quite strong when using chloroplast data, but that along the backbone in particular of the rest of the tree was rather weak whether using chloroplast, nuclear or combined data, and especially in parsimony analyses (Liu et al. 2017). There was some conflict in the topologies of trees obtained using nuclear markers and those using chloroplast markers, but allopolyploidy is common in the genus (Liu et al. 2018).
Knowledge of relationships along the backbone of the tree seems to be stabilising, i.e. on the relationships [Hauya [[Fuchsia + Circaea] [Lopezia [Gongylocarpus [Epilobeae + Onagreae]]]]] (Levin et al. 2003, 2004), and this is the topology followed above. However, Ford and Gottlieb (2007) found a clade [Hauya [Fuchsia + Circaea]] that was sister to other Onagroideae (see also M. Sun et al. 2016). Relationships are similar to those in Lenin et al. (2003, 2004) in the Angiosperms353 analysis of Maurin et al. (2021: Hauya not included), although the clade [Gongylocarpus [Epilobeae + Onagreae]] is not well supported within Onagreae relationships are somewhat different from those previously recovered.
Berry et al. (2004: ca 1/3 species included) examined relationships in Fuchsia and found that all the sections with two or more species sampled except section Fuchsia (paraphyletic) were monophyletic, and the species from Tahiti and New Zealand (with blue pollen) formed a clade sister to the rest of the genus. However, relationships along the spine of the tree had rather little support. For relations in and the circumscription of Oenothera, see e.g. Hoggard et al. (2004) and Levin et al. (2004) and references.
Classification. Wagner et al. (2007) describe all supraspecific taxa in the family and so they include sectional classifications of Fuchsia, Oenothera, etc.. Reflecting the new, but for the most part well supported phylogeny of the family, generic limits have been adjusted, so Oenothera has been expanded and Camissonia very much cut up (e.g. Levin et al. 2004); for all the nomenclatural changes involved, see Hoch and Wagner (2007). The Onagraceae website contains a largely up-to-date summary of the classification, etc..
Botanical Trivia. In 1827 Robert Brown recorded the phenomenon that is now called Brownian motion when observing the pollen grains of Clarkia pulchella.
Hugo de Vries thought that the abrupt appearance of Oenothera lamarckiana was an example of normal evolution, which for him was a process in which mutation = major change = speciation, natural selection not being involved. However, O. lamarckiana is a morphological variant caused by the breakdown of the permanent translocation system mentioned above (c.f. Linnaeus and Peloria [= Linaria, Plantaginaceae]).
LYTHRACEAE Jaume Saint-Hilaire, nom. cons. - Back to Myrtales
Herbs to trees; quinolizidine alkaloids +; vesturing spread over inside of vessel [Sonneratia], fibres +, septate; mucilage cells common; hairs uni- or bi(multi)cellular; leaves (spiral), lamina vernation flat to conduplicate, (margins dentate - Trapa), stipules +/0; (inflorescence determinate); pedicel articulated [?always]; flowers (3) 4 (5) 6(-16)-merous, heterostyly common; hypanthium (spurred), (0, but with K + C tube), often strongly ribbed and/or appendages [= epicalyx] alternating with K, C crumpled in bud, (0), initial development slow [?level]; A basically obdiplostemonous, (1- = and opposite K -many, centrifugal or centripetal), inserted just below C to near ovary, heteranthy +; (tapetal cells multinucleate); pollen grains (porate), (pseudocolpi 0, 6), (surface striate); (nectary at base of G); G superior, [2-6(-many)], (inferior), orientation variable, (placentation parietal), stigma capitate to punctate, also dry; ovules (1[Trapa]-few/carpel), outer integument 2-7(-9) cells across, inner integument 2(-3) cells across, parietal tissue 2-9(-15 - Cuphea) cells across, "chalazal strand" +, (postament +); (embryo sac much elongated); fruit a capsule, dehiscence irregular/circumscissile/loculicidal (indehiscent; berry), K often ± enclosing fruit; seeds usu. flattened; testa multiplicative, many-layered (not - Duabanga), exotesta various, invaginated mucilage hairs + (0), (sarcoexotesta - Punica), endotestal cells often elongated and tracheidal/sclerotic, (crystalliferous), (endotegmen of crossing fibres); (cotyledons folded); n = (5-)8(-11, + polyploids), chromosomes 0.5-4 µm long; x = 8, nuclear genome [1 C] (0.044-)0.78(-13.878 pg/(333-)673(-963) Mb; plastome rpl2 intron 0.
31 [list]/650: Cuphea (250), Diplusodon (105), Lagerstroemia (55 - A centrifugal), Nesaea (55 - probably to include Ammannia - then = 80), Rotala (45), Lythrum (36). Tropical, but some temperate. Map: from van Balgooy (1975), Trop. Afr. Fl. Pl. Ecol. Distr. 1 (2003) and S. A. Graham et al. (2005). [Photo - Flower]
Age. Estimates of the age of the family are (65-)50, 46(-29) Ma (Bell et al. 2010: minus Deocodon), ca 60 Ma (Sytsma et al. 2004) or rather older, ca 80 Ma (Inglis & Calvacanti 2018) and even (99.7-)95.5(-91.7) Ma (Berger et al. 2015); Gonçalves et al. (2020a) estimated an age of (77.6-)68.6(-63.8) Ma and X.-F. Zhang et al. (2021) an age of (86.8-)72.2(-63.8) ma, but these ages refer to a number of different topologies...
However, fossil evidence suggests that a crown group age for the whole family is likely to be at least 85 Ma. Pollen from Montana dated to the Lower Campanian 82-81 Ma has reliably been identified as Lythrum or its segregate, Peplis; there is somewhat younger (72-78 My) pollen from Siberia (Grímsson et al. 2011b: exquisite micrographs; S. A. Graham 2013 for a summary). Enigmocarpon paijai, known from both flowers and fruits in rocks 67-65 Ma from the Deccan Traps, India, belongs to but is unplaced within Lythraceae (S. Y. Smith et al. 2015 and references). The fossil Trapago is found in deposits 73-65 Ma, and other fossils assignable to Myrtales in general are perhaps slightly older (Crepet et al. 2004 and references).
Evolution: Divergence & Distribution. Sonneratia, a mangrove genus, has a long fossil record, its pollen, Florschuetzia, being distinctive (J. Müller 1978, 1984), and it may be Oligocene in age. Duabangaxylon, associated with Duabanga, another mangrove, is reported from deposits ca 65 Ma in Kutch, far western India (Shukla & Mehrotra 2017). Decodon, now restricted to eastern North America, was widely distributed in the North Hemisphere from the Eocene onwards and was more diverse than it is now (Ferguson et al. 1997 and references; Little et al. 2004); it is also known from the late Cretaceous of Mexico (Grímsson et al. 2012). See S. A. Graham (2013) for a summary and evaluation of the fossil record of the family.
The 100+ species of Diplusodon are thought to have evolved within the last ca 3.46 My, while stem Diplusodon is ca 58 Ma... (Inglis & Calvacanti 2018).
Taxa with everting testa hairs, which vary in their morphologies, are unique to the family but are scattered through it (S. A. Graham & Graham 2014). For morphology and phylogeny, see Tobe et al. (1998).
Ecology & Physiology. Sonneratia, with ca 7 species, is a notable element of mangrove vegetation from Southeast Asia to the Pacific. The nuclear genomes (1 C) of the mangrove species are (329.6-)326, 259(-255.4) Mb, about half the size of those of non-mangrove species (). For the evolution of the mangrove habitat, see Rhizophoraceae, also articles in Ann. Bot. 115(3). 2015, Suvarna Raju (2021: pollination), etc..
Pollination Biology & Seed Dispersal. Heterostyly is known from some Lythraceae (Barrett & Shore 2008).
Taxa whose seeds have mucilaginous hairs are more or less myxospermous; the hairs evert when the seed is wetted (Western 2011 for references). The fruits of Cuphea open by the placenta expanding and moving laterally, breaking through both the thin ovary wall and the hypanthium; the seeds are exposed on the placentae.
Genes & Genomes. A genome duplication, the LAINα event that has been dated to ca 68 Ma, involves both Lagerstroemia and Punica (Landis et al. 2018). S. A. Graham and Cavalcanti (2001) suggest that x = 8 is the basic chromosome number for the family. Nuclear genomes [1C] of the non-mangrove species are (963-)673(-333) Mb compared with (329.6-)326, 259(-255.4) Mb for the mangroves species ().
Chemistry, Morphology, etc.. The epicayx of Lythrum salicaria is initiated after the calyx, the inner stamens after the carpels, etc., and there are stamen fascicles opposite the petals (Cheung & Sattler 1967; Ronse Decraene & Snets 1991b; Rudall 2010); the petals here and in Trapa and Lagerstroemia initiate on time, but their early development is notably slow (Remizowa 2019). The stamens may be held on one side of the flower (also in some Onagraceae) and so causing rather weak monosymmetry; this is much more marked in Melastomataceae. However, some species of Cuphea, e.g. C. glutinosa, have quite strong monosymmetry that involves the corolla. Androecial development is both centrifugal (e.g. Lagerstroemia) and centripetal (Weberling 1989 and references; Ronse Decraene & Smets 1991). Pollen is notably variable (Graham 2006), and the oblate pollen of Cuphea may be triangular in polar view, being rather like pollen of Onagraceae in these respects (Kriebel et al. 2017). Species of the large genus Cuphea consistently have eleven stamens. When G = K, the carpels may alternate with or be opposite to them, when G = 2, the carpels may be transverse or median, when G = 3, the odd carpel is adaxial (Eichler 1878; Baillon 1877; Spichiger et al. 2002). Ovule morphology varies considerably. In taxa like Trapa, Sonneratia and Cuphea the embryo sac is much elongated, the nucellus sometimes being massive. There is usually a postament, and the base of the endosperm may be abruptly narrowed and protrude into the hypostase (see e.g. Täckholm 1915; Tischler 1917; Mauritzon 1934e; Joshi and Venkateswarlu 1936; Venkateswarlu 1937; Ram 1956: Trapa, and references).
The inferior ovary of Punica granatum is unique in flowering plants, appearing to have two (or three) superposed layers of carpels, the basal series (3) having axile placentation and upper series having intrusive parietal placentation and at least sometimes being 5 in number (Roth & Lindorf 1972). The placentation is fundamentally axile, the appearance of parietal placentation being the result of growth at the base of the ovary (Sinha & Joshi 1959 for vasculature), although this is difficult to understand if the series have different numbers of units. See Leins (1988) for the centripetal development of the androecium. In the other species of the genus, P. proto-punica, there is a more ordinary semi-inferior ovary. The seeds of Punica have a sarcotesta (e.g. Roth & Lindorf 1972), although this is often described as being an aril, not least by Wikipedia (1.2019)!
For general information, see S. A. Graham (1964, 2006); for some vegetative anatomy, see Little et al. (2004), for pollen, see J. Muller (1981b) and A. Graham et al. (1990), for development, see Cheung and Sattler (1967: Lythrum), for ovules, see Mauritzon (1939a), and for seed anatomy and morphology, see Grütter (1893) and S. Graham and Graham (2014).
Phylogeny. S. A. Graham et al. (2005) found maximum parsimony support for the topology [Decodon [[Lythrum + Peplis (= Lythrum)] [remainder of the family]]]; the remainder of the family formed two large clades. However, support along the back-bone was weak, and in maximum likelihood analyses there was some support for the three genera just mentioned being sister to one of these two clades. Z.-D. Chen et al. (2016) found Rotala to be sister to the rest of the family, but support for this position was weak. If Decodon is sister to the rest of the family, then seeds with mucilage hairs and 6-merous flowers are probably synapomorphies for the rest of the family. The relationships found by Gonçalves et al. (2020a) were [Heimia [Amannia [Trapa + Lagerstroemia]]], but this family was not the focus of their work. The old Sonneratiaceae (Sonneratia and Duabanga), plants of mangroves, are not monophyletic (Shi et al. 2000; Huang & Shi 2002; Graham et al. 2005; Narzary et al. 2016); Sonneratia itself may be sister to Trapa (e.g. Z.-D. Chen et al. 2016; X.-F. Zhang et al. 2021). The distinctive Punica was found to be sister to Woodfordia (Narzary et al. 2016), while [Woodfordia [Punica + Pemphis] were sister to the rest of the family in the plastome study of X.-F. Zhang et al. (2021). S. A. Graham et al. (2011) found that Rotala and Ammannia, previously thought to be close, were well separated, and they clarified relationships within the former genus. For a phylogeny of Cuphea, see S. Graham et al. (2006) and for that of Diplusodon, which has a fair bit of resolution at deeper nodes and can be divided into four main clades, each with a geographical signal, see Inglis and Calvacanti (2018).
Relationships found in the Angiosperms353 study by Maurin et al. (2021) should be consulted. For example, they found genera in the family formed two main clades. In one, Decodon and Lythrum (see above) were in a subclade, there was also a clade [[Sonneratia + Trapa] [Lagerstroermia + Duabanga]], and Rotala and Ammannia were both in this main clade, but widely separated. [Pemphis [Punica [Woodfordia + Galpinia]]] formed a clade sister to the rest of the other main clade (Maurin et al. 2021). Current classifications of the family in general and of Cuphea in particular will have to be retooled.
Two taxa with particularly distinctive morphologies:
Classification. For likely changes in generic limits around Ammannia, see S. A. Graham et al. (2010, esp. 2011).
Previous Relationships. Some morphologically distinctive taxa that were until recently separated as their own families - Trapaceae (water chestnut), Sonneratiaceae, Punicaceae (pomegranate) - nestle firmly within Lythraceae.
Synonymy: Ammanniaceae Horaninow, Blattiaceae Engler, Duabangaceae Takhtajan, Lagerstroemiaceae J. Agardh, Lawsoniaceae J. Agardh, Punicaceae Berchtold & J. Presl, nom. cons., Sonneratiaceae Engler, nom. cons., Trapaceae Dumortier
[[Vochysiaceae + Myrtaceae] [Melastomataceae [Crypteroniaceae [Alzataeaceae + Penaeaceae]]]]: inflorescences with at least the branches cymose.
Age. This node has been dated to around 88.2 Ma (Tank et al. 2015: Table S1), (84-)79, 74(-69) Ma (Wikström et al. 2001: internal relationships ± scrambled), (90-)75, 73(-59) Ma (Bell et al. 2010), (107-)95.1(-95.1) Ma (Berger et al,. 2015), (111.6-)100.8(-90.5) Ma (Gonçalves et al. 2020a) and (106.9-)94.2(-83.5) Ma (X.-F. Zhang et al. 2021).
Evolution: Divergence & Distribution. Vochysiaceae, Myrtaceae and Melastomataceae are notable components of tropical forests, particularly in the New World.
Chemistry, Morphology, etc.. Oil glands are found in the anthers of many Myrtaceae, and a number of other taxa in the Melastomataceae-Crypteroniaceae also have a very much expanded connective. Whether some staminal features - perhaps linked with pollination - are a higher-level apomorphy in this clade awaits further study.
[Vochysiaceae + Myrtaceae]: hairs simple, 1-2-celled; K and C imbricate; post-zygotic incompatibility system [?all]; style depressed in apex of gynoecium; fruit a capsule.
Age. The two families diverged 100-93 Ma (Sytsma et al. 2004), (107-)101(-95) Ma (Berger et al. 2015), (96.5-)91.7(-89.9) Ma (Thornhill et al. 2012a: combined constraints), 72.3/61.9 Ma (Tank et al. 2015: Table S2) or (106.9-)86.4(-83.5) Ma (X.-F. Zhang et al. 2021).
Evolution: Divergence & Distribution. Sytsma et al. (2004) discussed the age and biogeographic history of the whole group in some detail.
VOCHYSIACEAE A. Saint-Hilaire, nom. cons. - Back to Myrtales
Trees (lianes); 5-deoxyflavonoids +; plants Al-accumulators; pericyclic fibres at most few; small phloem bundles inside xylem, sclerified bundles in pith; sclereids, mucilage cells/ducts +/0; leaf traces run along stem before entering petiole; cuticle waxes ± grouped parallel platelets; stomata also paracytic; indumentum often brown, hairs unicellular; leaves leathery, lamina vernation conduplicate, (venation eucamptodromous - Callisthene), stipules cauline; inflorescence terminal (axillary), lateral cincinni +; flowers strongly mono- or asymmetric, plane of symmetry oblique; hypanthium 0, K basally connate, aestivation quincuncial, one adaxial-lateral K larger, variously nectariferous; C aestivation quincuncial [when 5]; fertile A 1, opposite abaxial-lateral C [on plane of symmetry], anther about as long as filament, filaments straight in bud; (pollen striate); G [3 (4)], odd member adaxial, ovary ± tapering into style, stigma punctate to subcapitate; ovules epitropous, outer integument 2-3 cells across, inner integument ca 2 cells across; n = 11, 12, x = ?, chromosomes ca 1 μm long.
7 [list, to tribes]/220. Tropical America, W. Africa. Map: from Stafleu (1954) and Trop. Afr. Fl. Pl. Ecol. Distr. 1 (2003). [Photo - Flower.]
Age. The age of crown-group Vochysiaceae is some 36-33 Ma (Sytsma et al. 2004), (52-)39(-28) Ma (Berger et al. 2015), around 20 Ma (X.-F. Zhang et al. 2021) or (66.7-)50(-34.9) Ma, rather considerably older (Gonçalves et al. 2020a).
1. Erismadelphus Mildbraed + Korupodendron Litt & Cheek
Wood rays uniseriate, included phloem [E.]; non-wood anatomy?; (3 K C-like - K.), C 5, nectariferous cavity running down one side of the inferior ovary, (spurs 2, short, stout - E.); anther connective massive [E.], staminodes 2; G inferior, unilocular, (stigma unilateral); ovule single; ?embryology, etc.; fruit samaroid, with 5 wings [= accrescent sepals]; seed coat compressed, vascularized; cotyledons ± plano-convex; testa undifferentiated, with vascular bundles, germination ?hypogeal [K.]. E. = Erismadelphus, K. = Korupodendron.
2/3. West Africa (see Map above).
Age. The crown-group age of this clade is (27.2-)15.6(-5.8) Ma (Gonçalves et al. 2020a).
[Vochysieae + Qualea, etc.]: some rays multiseriate; nectariferous spur ± well developed; C 1; micropyle long, hypostase +, placental obturator +; embryo sac much elongated; cotyledons convolute.
Age. This clade is (53.2-)40.3(-28.8) Ma (Gonçalves et al. 2020a).
2. Vochysieae Dumortier
Cork outer cortical; (included phloem +); midrib bundle semicircular/interrupted annular, secretory ducts in midrib/0; (hairs stellate - E.); (bract/eoles recaulescent - V.); C (+ to 4 reduced; 5, 3, 0); A (initially median, moving out of plane of symmetry - E.), inserted on K [S., V.], (staminodes 2); (exothecium unthickened, secondary pollen presentation + - some V.), (staminodes 2); pollen grains (tricellular - S.), (almost smooth - V.); G (inferior, 1 loculus developing - E.), (stigma unilateral); ovules 2/carpel, outer integument 7-12 cells across, inner integument 3-4(-8 - S.) cells across, parietal tissue -40 [V.] cells across (integuments vascularized - S.); (spurred K deciduous - E.); fruit (samaroid, with 4 wings [= sepals] - E.), (nut), loculicidal capsule; seed 1; (seed winged, wing of hairs); seed coat largely exotestal, undifferentiated, crystal layer 0, tegmen 0, (with vascular bundles - E.); (cotyledons massive, plano-convex E.). E. = Erisma, S. = Salvertia, V. = Vochysia.
4/126: Vochysia (100/?140), Erisma (20). South America, mostly Amazonian, also Panama and the Atlantic Forest.
Age. Crown-group Erismeae are some (24.2-)14.3(-5.5) Ma (Gonçalves et al. 2020a: ?sampling).
3. Qualea Aublet, etc. / QRC clade.
(included phloem +); cataphylls +/0; midrib bundle shallowly arcuate, stomata paracytic; (leaves held in one plane - C.), stipules as glands/with extrafloral nectaries/minute; (bracteoles 0 - some Q.); A not in plane of symmetry; (nectary spur 0 - some Q.); C 5/3/1 (+ reduced C); A (thecae attached their length to connective), (with hairs); staminodia 0-4; pollen striate-reticulate; ovules several/carpel, 2-ranked, outer integument 2-4 cells across, inner integument 2-4 cells across, parietal tissue ca 7-20 cells across, (nucellar cap +), (postament + - Q.); megaspore mother cells several, delayed fertilization; fruit a loculicidal capsule, (outer layer of pericarp separating irregularly); seeds (winged, wing circumferential - C.); testa (multiplicative), mesotesta ?not sclerotic, endotestal cells ± U-thickened, pectic, crystalliferous or not, exo/mesotegmic cells fibrous, thick-walled or not, endotegmen tanniniferous [Q.] exotestal hairs thick-walled, a few other layers persisting, but rest and tegmen disorganised; cotyledons convolute [= spirally folded]. C. = Callisthene, Q. = Qualea, R. = Ruizterania.
1-3/63: Qualea (60). Tropical Central and South America
Evolution: Divergence & Distribution. For additional ages within Vochysieae, see Gonçalves et al. 2020a).
Gonçalves et al. (2020a) could not be sure of the identity of the leaf fragments described as Qualea siwalica, from Miocene deposits from the Siwaliks in western Nepal. Given that its relatives would be New World taxa, this must come as something of a relief.
The phylogenetic "fuse" of Vochysiaceae is around 50 (Gonçalves et al. 2020a) to 60 (Berger et al. 2105) million years. The present distribution of Vochysiaceae on either side of the Atlantic was thought likely to be the result of dispersal to Africa from America (Sytsma et al. 2004; Berger et al. 2015: differences only in detail). However, Gonçalves et al. (2020a) found that the African Vochysiaceae were sister to the rest of the family, and suggested [Africa + South America] was the ancestral area for both [Vochysiaceae + Myrtaceae] and Vochysiaceae, and for the New World taxa the Cerrado seems to be central.
Although Vochysiaceae are a rather small family, they encompass a substantial amount of both vegetative and floral variation.
Pollination Biology & Seed Dispersal. Visitors to the flowers are various and include hummingbirds and hawkmoths (Carmo-Oliveira et al. 2017 for literature). In at least some Qualea and relatives, fertilization is delayed; the ovules develop slowly, and the pollen tubes spend some time in the obturatal area (Carmo-Oliveira et al. 2020).
Plant-Animal Interactions. Swollen stem-type domatia in Vochysia vismiaefolia developed only after the ant Pseudomyrmex sp. started excavating internodes, but these domatia could also be induced by simply drilling little holes into the internodes (Blüthgen & Wesenberg 2001).
Genes & Genomes. For cytological information, see Yamagishi-Costa et al. (2018).
Chemistry, Morphology, etc.. At least in Vochysia guatemalensis there are conspicuous, symmetrically-arranged mucilage canals in the pith; Qualea has trilacunar nodes (pers. obs.).
There appear to be colleters at the adaxial bases of the petioles and sepals (Boesewinkel & Venturelli 1987). Leaves of small saplings may have short petioles and swollen leaf bases. The leaves on the branches of Callisthene, although opposite, form monolayers by twisting of the stem/petioles (c.f. Coffea!).
The flowers vary in the number and arrangement of their parts and perhaps also in their basic symmetry, however, the literature is somewhat confusing over this and also over floral development; for early work, see e.g. Baillon (1874) and Eichler (18 ). More recently, floral diagrams are to be found in Stafleu's monograph (1952: Fig. 1; 1953: Fig. 1; 1954: Fig. 4; Keay & Stafleu 1952: Fig. 1), Kopka and Weberling (1984), etc.. The single stamen may be opposite the abaxial-lateral C or closer to the adjacent K; in the latter case, it is off the plane of floral symmetry, while the staminodes are generally (?always) opposite members of the corolline whorl (Stafleu; Kawasaki 1998; also Litt & Cheek 2002; Litt & Stevenson 2003b). Note that Litt and Stevenson (2003b: Fig. 2) and Gonçalves et al. (2020a: Fig. 6) show the single stamen as being opposite or somewhat oblique to what one would interpret as being the abaxial C (but see below), although Litt and Stevenson (2003b) had found that the anther of Erisma was initially opposite the petal and on the plane of symmetry of the flower, becoming displaced only late in development, although Stafleu (1953) suggests that the two positions of the stamens being discussed reflect the fact that they belong to different staminal whorls... Litt and Stevenson (2003b) and Gonçalves et al. (2020a) illustrated the spur in all taxa as being associated with the adaxial sepal (a simplistic interpretation of their diagrams), while in Kawasaki (1998: Fig. 6), Kopka and Weberling (1984), Stafleu, etc., it comes from or is opposite to an adaxial-lateral sepal; the first authors show the symmetry of the flower in Vochysieae as being strongly oblique in relation to the inflorescence axis, although the floral axis was not indicated, however, bracteoles are generally indicated by Stafleu. Neither Litt and Stevenson (2003b) nor Gonçalves et al. (2020a) indicated the position of the inflorescence axis in other taxa, Kawasaki (1998) did not indicate the positions of either axis, while Stafleu indicated perianth aestivation, the positions of bracteoles and the floral axis, showing (nearly) all flowers as being oblique to the axis in the same way. Litt and Stevenson (2003b) and Gonçalves et al. (2020a) indicated that the fertile stamen in Salvertia and Vochysia was slightly oblique to the petal that was drawn as being abaxial, while Kopka and Weberling (1984) and Kawasaki (1998) showed that stamen as being opposite the petal, furthermore, Kawasaki (1998) showed variation in the positional relationships of the carpels to the rest of the flower while in Litt and Stevenson (2003b) and Gonçalves et al. (2020a) this relationship was shown as being invariant. Litt and Stevenson (2003b) and Gonçalves et al. (2020a) did not indicate overlap of any perianth members while Kawasaki (1998) and Stafleu did. Finally, the spur in Vochysieae is described as being receptacular in origin by Kopka and Weberling (1984) and calycine in origin in Carmo-Oliveira et al. (2018); the two African taxa hardly have spurs, rather, there is a nectariferous cavity on one side of the inferior ovary.
The ovary is initiated in an inferior position, the superior ovaries in mature flowers of Vochysieae being secondary (Litt 1999; Litt & Stevenson 2003a).
Carmo-Oliveira et al. (2020) noted that the members of the [Qualea-Ruitzerania-Callisthene] clade that they examined had a multicellular archesporium, often more than one embryo sac, and delayed maturation of the embryo sac and of fertilization - the pollen tubes might hang out for several days on the obturator. Corner (1976) described the ovules of Qualea sp. as being long-exostomal (see also Carmo-Oliveira et al. 2020: e.g. Callisthene). The integuments in Vochysieae vary considerably in thickness, but the outer integument is always thicker than the inner (Carmo-Oliveira et al. 2020).
For additional information, see Kawasaki (1998: Erisma, 2006: general), for wood anatomy, see Quirk (1980) and Sajo and Rudall (2002, also leaf anatomy), for bark, see Roth (1972), and for ovules and seeds, see Boesewinkel and Venturelli (1987).
Phylogeny. Relationships have been unclear here for some time. Erismieae, containing the tropical American Erisma and the West African Erismadelphus and Korupodendron, were thought to be monophyletic. They have G inferior; 1-2 lateral to apical ovules/ovary; fruit samaroid, with persistent enlarged K; seed single, testa undifferentiated, with vascular bundles. Vochysieae are probably not monophyletic (Litt 1999). A recent plastome analysis by Gonçalves et al. (2020a) showed rather different relationships, with the African Korupodendron and Erismadelphus being sister to the rest of the family, within which Erisma was sister to the remainder - i.e. the old Erismeae are paraphyletic in this telling of the story (note, however, that Gonçalves et al. were cautious in inferring much from their tree, noting that they had looked at chloroplast data alone). Indeed, Baker et al. (2021: see the Seed Plant Tree - all genera of Vochyiaceae included) found that Erisma was embedded in Vochysieae, and sister to Vochysieae was a clade including Callisthene, Qualea, etc., that lacks a name. However, Maurin et al. (2021) found the relationships [[African taxa] [Erisma [[Vochysia + Salvertia] [Callisthene, etc.]]]], although support for the relationships between the American clades was rather weak. The recognition of Ruizterania (Marcano-Berti 1969) may make Qualea paraphyletic (Gonçalves et al. 2020a).
Previous Relationships. Because of their distinctive monosymmetric, spurred flowers Vochysiaceae were often associated with families with more or less similar flowers that are now no longer thought to be at all closely related, Euphronia (see Malpighiales-Euphroniaceae) being one frequent associate (e.g. Mabberley 1997; Takhtajan 1997). Takhtajan's (1997) Vochysiales also included families like Malpighiaceae (Malpighiales), Tremandraceae (= Oxalidales-Elaeocarpaceae) and Krameriaceae (Zygophyllales); Cronquist's (1981) Polygalales, in which he included Vochysiaceae, were even more heterogeneous.
MYRTACEAE Jussieu, nom. cons. - Back to Myrtales
Ethereal oils + [usu. terpenes]; wood fibres with distinctly bordered pits; leaves with glands; apex of anther connective glandular [terpene-producing]; pollen grains small [11.6 (13.94 S.D.) μm long], oblate, triangular in polar view, parasyncolpate [colpi margins spreading and forming triangular apocolpial polar area], pseudocolpi 0; x = 12 (?11, ?6), nuclear genome [1 C] (0.063-)0.614(5.989) pg/(234-)488.4(-1785) Mb [?level].
131 [list: to tribes]/5,900) - three main groups below. Worldwide, mostly tropical-warm temperate.
Age. Crown Myrtaceae may date to 87-85 Ma (Biffin et al. 2010a), 95-84 Ma (Sytsma et al. 2004), or (88-)85(-84) Ma (Berger et al. 2015); ages in Wilson (2011) are largely similar. In a comprehensive analysis also using fossil pollen, Thornhill et al. (2012a: dates for root-only calibrated tree much younger, 2015) suggest ages for crown group Myrtaceae of (97-)90.6, 84.6(-73.7) Ma, Gonçalves et al. (2020a) ages of (91.5-)86.3(-83.5) Ma and X.-F. Zhang et al. (2021) ages of (83.6-)67.5(-52.4) Ma.
For a summary of fossils attributed to Myrtaceae see Biffin et al. (2010a; also Crepet 2008); Thornhill and Macphail (2012) evaluate the fossil pollen record. For interesting Eocene fossils from Australia, see Basinger et al. (2007) and from Colorado, see Manchester et al. (1998). Pigg et al. (1992) described a fossil from the Palaeocene that they thought was close to Myrtaceae-Myrteae-Psidium, and Cretaceous pollen (Wilson 2011; see also Thornhill & Macphail 2012) and wood (Myrteae) (Vasconcelos et al. 2017) can also be assigned to the family.
1. Heteropyxidoideae Reveal (Psiloxyloideae in older literature)
Plant "tanniniferous"; leaves spiral; plant dioecious; A erect in bud, each A with separate trace; staminate flowers: anther sacs each opening separately; pollen with closely-fitting island in polar apocolpial area; pistillode +; carpelate flowers: staminodia +; G superior, base narrow; embryo sac bisporic, 8-nucleate [Allium type]; endotesta crystalliferous, cells periclinally elongated; x = 12.
2/4. S.E. Africa, Mascarenes.
Age. Around (45-)40(-38) Ma is the suggested crown-group age of this clade in Sytsma et al. (2004) and (64.5-)42.6(-22.7) or (60.6-)39.7(-20.2) Ma in Thornhill et al. (2012 and 2015 respectively).
1A. Heteropyxideae Harvey
Trees; terpenes 0; axial xylem parenchyma 0; epidermal wax crystalloids as small platelets; leaves with domatia, stipules minute; (plant monoecious); staminate flowers: stamens = and opposite C (+ 1-3 opposite K); carpelate flowers: G [(2-)3], stigma capitate; fruit a capsule, style green, persistent; ovules hemitropous; seeds with narrow wings at either end, exotesta with tangentially elongated cells, walls scalariform-reticulately thickened, exotegmic cells elongated.
1/3: Heteropyxis. South eastern Africa. Map: from MO herbarium records, green.
Synonymy: Heteropyxidaceae Engler & Gilg, nom. cons.
1B. Psiloxyleae (Croizat) A. J. Scott - Back to Myrtales
Trees; secretory canals in the young stem; vestured pits?, axial xylem parenchyma?, fibres septate, crystalliferous; nodes ?; glands not producing ethereal oils; plant glabrous; stipules colleter-like; (plant polygamodioecious), pedicels articulated; flowers 4-5(-6)-merous; C coriaceous, caducous, punctate, staminate flowers: A 2x C, anthers versatile; carpelate flowers: G [3(4)], style 0, stigma large, lobed; ovules hemicampylotropous; fruit a berry, punctate; exotesta cells large, exotegmen crushed.
1/1: Psiloxylum mauritianum. Mascarenes (Map: red, see above).
Synonymy: Psiloxylaceae Croizat
2. Myrtoideae Sweet
Trees and shrubs; terpenes diverse and abundant, exudates gums [kinos]; (plants Al accumulators); (cork cambium superficial); axial parenchyma +; sieve tubes with non-dispersive protein bodies; (stomata paracytic); hairs unicellular, rather thick-walled; lamina vernation variable, stipules 2/several, colleter-like, or 0; flowers (3-)4-5(-8)-merous; K (with a single trace), C (0-)4-5(-12), often deciduous; A many, conspicuous, locule pairs open by common slit; pollen grains (syncolpate); G partly superior, opposite K or C, if 3, odd member abaxial, placentae well-developed, minor stylar bundles 0, stigma punctate to capitate (peltate), also dry; micropyle zig-zag [?always], outer integument 2-6(-12) cells across, inner integument 2(-4) cells across, (unitegmic, integument 6-8 cells across, vascularized), parietal tissue 2-12 cells across, nucellar cap 0 (-3 cells across - v. rare), hypostase 0/+, (postament +), (obturator +); (seed pachychalazal), exotesta variously thickened, endotesta thickened or not, crystalliferous, (sclerotic palisade cells at the micropyle), (exotegmen 0); embryo green or white, straight or curved, cotyledons very variable; x = 11, chromosomes 2> μm long; seedlings with ring of hairs/coleorhiza at base of hypocotyl (not - Psidium).
129/5,894 [Nic Lughadha et al. 2016]. Tropical (temperate), esp. Australia (map: from Meusel et al. 1978; Trop. Afr. Fl. Pl. Ecol. Distr. 1. 2003; Lucas 2007).
Age. Thornhill et al. (2012a) gave ages for crown-group Myrtoideae of (90.3-)83, 71.3(-64.9) Ma, the lower age, some (78.3-)71.5(-65.4) Ma, was preferred by Thornhill et al. (2015); (86-)80(-70) Ma are the ages suggested by Sytsma et al. (2004) and around 62Ma by Berger et al. (2015).
For wood of Myrceugenelloxylon antarcticus, fossil from Antarctica in Late Cretaceous deposits, see Poole et al. (2003). Woods of Callistemoxylon, Eucalyptus (E. dharmendrae) and Tristania from Early Palaeogene rocks of the Deccan Traps can all be referred to Myrtoideae (Wheeler et al. 2017).
[Lophostemoneae + Xanthostemoneae]: leaves spiral.
Age. The age of this clade is around (69.7-)56.3(-37) Ma (Thornhill et al. 2012a: combined constraints).
2a. Lophostemoneae P. G. Wilson
A fasciculate; fruit (baccate - Kjellbergiodendron); seeds (1/fruit), flattened or linear; cotyledons folded, vernation various.
4/7. Borneo, E. Malesia, eastern Australia.
Age. Kjell/Lopho diverged (57.4-)39.4(-21.2) Ma (Thornhill et al. 2012a: combined constraints).
2b. Xanthostemoneae P. G. Wilson
(Leaves opposite); A free, anther "point of attachment enclosed by connective"; seeds flattened (and winged); cotyledons accumbent.
3/48: Xanthostemon (45). Eastern Malesia, the Philippines, to Australia and New Caledonia.
[[Osbornieae + Melaleuceae] [the rest]]: ?
[Osbornieae + Melaleuceae]: flowers 1 or 3/axil; embryo straight.
Age. The age of this clade has been dated to (68.9-)55.3(-42.9) Ma (Thornhill et al. 2012a: combined constraints).
2c. Osbornieae P. G. Wilson
Shrub; axillary bud enclosed by swollen petiole base; lamina isobilateral; K and C similar, bases broad, subpetal-like adaxially; G 2, collateral, placentation basal-axile; to ca 8 ovules/carpel; fruit subbaccate, leathery, indehiscent, P persistent; seed 1/fruit; embryo straight, radicle short, cotyledons large, subspherical, flat.
1/1: Osbornia octodonta. Borneo to Palau, N. Australia.
2d. Melaleuceae Burnett
Leaves usu. spiral, lamina (venation parallel); inflorescence spike-like or capitate; flowers (calyprate - fused K); A often fasciculate; ovules 1-many/carpel; capsule (dehiscence tardy); seeds linear, (winged); x = (8-10).
2/335: Melaleuca (334). Mostly Australia, esp. southwest, few Malesia.
Synonymy: Melaleucaceae Vest
2e. Kanieae Engler
(Leaves spiral); A often fasciculate; G half inferior; seeds 1-many; cotyledons circinate/flat/variously folded..
9/60: Tristaniopsis (40). Especially east Australia, Malesia to Myanmar, New Caledonia and ?New Zealand.
Synonymy: Kaniaceae Nakai
[Backhousieae + Metrosidereae + Tristanieae + Syzygieae]: ?
2f. Backhousieae P. G. Wilson
A free; G semi-inferior; ovules 1-2/carpel; fruit thin-walled, indehiscent, seeds 1-2/fruit; embryo curved, cotyledons incumbent.
2/10: Backhousia (8). Eastern Australia.
2g. Metrosidereae P. G. Wilson
Vesturing spread over inside of vessel; A free; G semi-inferior; seeds linear, cotyledons flat.
1/60. The Philippines, New Guinea to New Zealand, Hawai'i and Pitcairn Island, also southern South America (= Tepualia s. str.).
Age. Fossils identified as Metrosideros, some perhaps belonging to the monophyletic subgenus Metrosideros and some that would have been called Mearnsia in the past, have been discovered in Oligocene-Miocene deposits ca 30 Ma, perhaps as young as 16 Ma, in Tasmania (Tarran et al. 2016, 2017), while there are also fossils of the latter type in New Zealand (see Pole et al. 2008).
2h. Tristanieae Burnett
A free/(fasciculate); fruit baccate (Tristania); cotyledons (accumbent - Tristania) flat.
3/43: Tristania (40). The Philippines, New Guinea to New Caledonia, eastern Australia.
2. Syzygieae P. G. Wilson
Plant usu. glabrous; stomata (cyclostaurocytic); (calyptra +); G usu. ; fruit baccate (± dry), usu 1-seeded; testa apparently 0/leathery; embryo straight, cotyledons thick, ruminate/foliaceous, obvolute.
1/1,045. Tropical and subtropical Old World. Photo - Flower.
Age. 21.7-21.5 Ma leaves from S.E. Australia have been identified as Syzygium (Tarran et al. 2018).
[Syncarpieae + Eucalypteae]: plant usu. glabrous.
2. Syncarpieae P. G. Wilson
Buds with scales; (hairs when young); flowers sessile, in groups, connate basally; G inferior, placentae basal; ovules several; seeds linear; embryo straight, cotyledons obvolute, radicle ca 1/2 their length.
1/3: Syncarpia. Eastern Australia.
2. Eucalypteae P. G. Wilson
Plant ectomycorrhizal; cyanogenic glucosides + [Eucalyptus]; hairs on (young plants), (multicellular, branched); (leaves spiral); calyptra common K/C/(hypanthium); C (connate), (complex: keel + corolline portion); A fasciculate, (arising from stemonophore)/not, (staminodes numerous, abaxial); G [2-7], style (barely impressed); 3-many ovules/carpel; fruit (1-seeded); cotyledons deflexed, obvolute/large reniform, peltate, much contorted.
Age. The age of this clade (Stock, Euopsis sister) is estimated to be (58.7-)55.3(-52.5) Ma (Thornhill et al. 2012a: combined constraints) or ca 59.2 Ma (Thornhill et al. 2019).
There are fossils of Eucalyptus, possibly of the relatively widespread subgenus Symphyomyrtus, in early Eocene deposits of Argentinian Patagonia ca 51.9 Ma old (Wilf et al. 2010; esp. Gandolfo et al. 2011; Hermsen et al. 2012).
7/935: Eucalyptus (800), Corymbia (115). Australia, few Malesia, 1 sp. New Caledonia.
2a. Lindsayomyrteae P. G. Wilson
Leaves spiral, remarkable purple(-blue) when young; androecium fasciculate; G ; pericarp thin, fruit dehiscing irregularly; seeds 1-3, 1/carpel; embryo straight, cotyledons massive, unequal, largely flat.
1/1: Lindsayomyrtus racemoides. Eastern Malesia, N. Queensland, Australia.
[Leptospermeae + Chamaelaucieae]: ?
Age. This clade is ca 50 Ma (Thornhill et al. 2012a).
2b. Leptospermeae de Candolle
Leaves usu. spiral; flowers (in heads), sessile or not; A (10-), shorter than C or not, (basally connate), (fasciculate); G [(-12)]; ovules 1-many/carpel; fruit indehiscent or not; seeds winged, linear [Leptospermum]; testa thin; cotyledons broad, flat, longer than hypocotyl.
10/178: Leptospermum (80), Kunzea (60). Australia, esp. S.W. (genera), a few Malesia, New Zealand.
Age. This clade (Kunzea sister) is around (42.5-)33.3(-25.2) Ma (Thornhill et al. 2012a: combined constraints).
Synonymy: Leptospermaceae Berchtold & J. Presl
2c. Chamaelaucieae de Candolle
Shrubs (small trees); usu. glabrous; leaves (spiral); flowers solitary; A (4)/5 [opposite K or C]-15/(-many), (fasciculate, opposite K), (not inflexed in bud), anthers (basifixed), usu. with connective gland, (staminodes 10); (secondary pollen presentation + [stylar hairs]); pollen (brevicolpate); ovules 1-many/carpel; fruit (indehiscent), seeds reniform/angular, with elaiosome/aril, testa (thin); embryo curved, hypocotyl massive, cotyledons small, at end of recurved neck; n = (5-)11.
35+/600+ (and ca 150 to be described): Verticordia (100), Calytrix (75), Thryptomene (56), Darwinia (45), Scholtzia (40). Australia, a few species Malesia to China, New Caledonia.
Age. Crown-group Chamaelaucieae (Ochrosperma sister) are (51.9-)46.8(-42.2) Ma (Thornhill et al. 2012a: combined constraints).
Synonymy: Baeckeaaceae Berchtold & J. Presl, Chamelauciaceae Rudophi
2. Myrteae de Candolle
Lamina (venation triplinerved); (hypanthium +); K (connate [= calyptra], circumscissile), C (fall as unit); A (4), ± straight (incurved); pollen grains longicolpate, (to 50 μm across - Octamyrtus); G inferior, [(2-18)], transseptal vascular bundles +; fruit baccate; ovules 1-many/carpel; seeds 1-many/fruit; testa (multiplicative, ± sclerotic - e.g. Psidium, Myrtus); embryo curved or not, cotyledons fleshy, (fused), (variously folded)/foliaceous/small.
47/2,690: Eugenia (1,115), Myrcia (770), Calyptranthes (130), Psidium (100), Campomanesia (80), Myrcianthes (50), Myrceugenia (40), Plinia (40). Tropical (temperate), esp. South America. [Photo - Bark, Flower, Fruit.]
Age. Crown-group Myrteae have been dated to (53.6-)50.9(-50) Ma (Thornhill et al. 2012a: combined constraints, Myr comm sister), ca 90 Ma (Murillo-A et al. 2016) and the Miocene ca 18 Ma (Berger et al. 2016; see also Vasconcelos et al. 2017).
Synonymy: Eugeniaceae Berchtold & J. Presl, Myrrhiniaceae Arnott
Evolution: Divergence & Distribution. For ages of various clades in the family, see Biffin et al. (2010a) and Thornhill et al. (2012a, 2015, 2019: Eucalypteae), also Vasconcelos et al. (2017: Myrteae). The pollen record suggests the existence of at least some tribes in the late Cretaceous (Wilson 2011), but this is inconsistent with many molecular divergence dates (see also Vasconcelos 2017 for an evaluation of much fossil literature). Some dates for the same node diverge widely. Thus crown-group Myrteae are dated to the Cretaceous ca 90 Ma by Murillo-A et al. (2016) and the Miocene ca 18 Ma by Berger et al. (2016; Vasconcelos et al. 2017 for literature and dates); Thornhill et al. (2012a) also emphasized similar differences.
Thornhill et al. (2015) thought that although Myrtaceae may have been Gondwanan in origin, none of the 22 disjunctions they examined could unambiguously be linked to geological vicariance events; Myrtoideaea may have originated in Australia. Myrteae are the largest tribe in the family and include species with fleshy fruits; they may have originated in the New Zealand-New Caledonia-Australia area, either in the early Palaeocene ca 65.5 Ma (macrofossil evidence) or substantially later in the mid-Eocene ca 40.8 Ma (palynological evidence), and then achieved their broader largely austral distribution via Gondwana (Vasconcelos et al. 2017). de la Estrella et al (2019b) also suggested that Myrtoideae, and Myrteae in particular (see Vasconcelos et al. 2017 for a phylogeny), originated in the Australia-New Zealand area; Myrtaceae make up the third commonest angiosperm family among the fossils found in Antarctica, which may have been important in enabling the distribution of the tribe. However, not only are dates uncertain, but the status of New Zealand and New Caledonia during this period is unclear: Were they always emergent, or submerged for part of the time, and/or were there metapopulations of Myrteae on ephemeral islands (Vasconcelos et al. 2017; see also Condamine et al. 2016, etc.)? Mazine et al. (2018) suggest that Myrtus was originally associated with dry non-tropical climates in South America, as were South American Myrteae in general; the Brazilian Atlantic Forest was important in their susbsequent diversification. Mediterranean Myrtus itself is part of a clade that is otherwise from Central and South America. For diversification rate shifts within Myrteae, see Vasconcelos et al. (2017). Eugenia is the most species-rich tree genus in the Altantic Forest of Brazil (Mazine et al. 2014). The ca 200 Old World species of Eugenia in sect. Jossinia appear to represent a single movement of the genus (c.f. van der Merwe et al. 2005; Bernardini et al. 2014), perhaps originally from Atlantic and dry forests in South America, to the Old World, possibly via New Caledonia, where E. brongniartiana, sister to the rest of the section, is to be found; the genus is ca 40.9 or ca 30.3 Ma (Mazine et al. 2018). However, only 14 species of Jossinia were examined, and relationships in the trees presented varied substantially (Mazine et al. 2018), so more news from this area can be expected.
Also in the New World Myrteae, the speciose Myrcia s.l. with 700-800 species, often montane plants, may have begun diversifying in the Brazilian Atlantic forest ca 28 (36-21) Ma; it is notably diverse in eastern Brazil, the Caribbean, and the Guyana Highlands (Santos et al. 2017). Vasconcelos et al. (2018) found that there was remarkably little floral variation in Myrcia s.l. and the little variation that the group did show was not particularly correlated with phylogeny. There is some variation in fruit anatomy (Galan et al. 2016), but there is, however, considerable variation in chemistry (Stefanello et al. 2011), vegetative feaures and plant habit, and variation in such features in particular help separate the species of the genus (Vasconcelos et al. 2018). Interestingly, in Myrcia s.l., ontogeny and phylogeny are inversely correlated, that is, characters that appear later in ontogeny are more indicative of deeper relationships (Vasconcelos et al. 2016). Amorim et al. (2019) discuss the evolution of some characters here, and suggest that the Atlantic Forest was the ancestral area of the genus, while Vasconcelos et al. (2019a) looked at the extensive floral variation in Myrteae in the conext of the phylogeny of the tribe.
Ladiges et al. (2011, see also 2012) suggested that within two clades of Eucalyptus s.l., Late Cretaceous-Palaeocene in age, there was independent adaptation to arid/semi-arid conditions. Hermsen et al. (2012, also Macphail and Thornhill 2016 and other papers in Australian J. Bot. 64(7-8). 2016) in their evaluation of the fossil evidence, thought that crown-group Eucalypteae were early Palaeocene or Eoceae in age, while Thornhill et al. (2015) dated crown-group Eucalyptus to the Late Eocene (35-)34.4(-33.9) Ma. There are fossils of Eucalyptus, possibly of the relatively widespread subgenus Symphyomyrtus, in early Eocene deposits of Argentinian Patagonia ca 51.9 Ma old (Wilf et al. 2010; esp. Gandolfo et al. 2011; Hermsen et al. 2012), and there are also fossils of Eucalyptus from Early Miocene New Zealand (Rozefelds 1996; Pole 2003). Eucalypteae are no longer found in either South America or New Zealand, but see Fagaceae for discussion about such distributions.
Fossils identified as Metrosideros, some perhaps belonging to the monophyletic subgenus Metrosideros and some that would have been called Mearnsia in the past, are known from Oligocene-Miocene deposits ca 30 Ma, perhaps as young as 16 Ma, in Tasmania (Tarran et al. 2016, 2017). However, Metrosideros now grows in eastern Malesia, the Bonin Islands, throughout Melanesia and Polynesia, New Caledonia (>20 species), Hawai'i, and New Zealand, but it is unknown from Australia; most of this wide distribution is attributable to Metrosideros subgenus Metrosideros. This may have radiated from New Zealand, its small seeds being dispersed by wind (Wright et al. 2000b, 2001; see also Pillon et al. 2015), and its arrival in Hawai'i is estimated to be a mere (6-)3.9 Ma, probably on Kaua'i (Percy et al. 2008) or ca 3.1 Ma (Dupuis et al. 2020). However, understanding the biogeography of the genus is difficult, partly because relationships within it are unclear, and partly because it also includes the South African M. angustifolia and the Chilean M. stipularis, perhaps sister species (Pillon et al. 2015). However, Dupuis et al. (2019) found that M. laurifolia, from New Caledonia, was sister to the rest of the genus, although there was litle resolution of relationships between the Hawaiian accessions. Metrosideros collina, the only species known from the Marquesas Islands, may have given rise to the Hawaiian clade with its some 25 "taxa" that show a considerable amount of variation in habit in particular. Indeed, Choi et al. (2021) emphasized the rapid evolution of these Hawaiian taxa, both hybridization as well as diverse recombinations of a rich pool of ancestral variation being involved. This seems not to fit with the involvement of M. collina in the story; there substantial long distance dispersal had been integral to its arrival in the Marquesas, but perhaps the adaptive radiation on Hawaii occurred as Metrosideros took advantage of the greater ecological opportunity there (Choi et al. 2021).
The Malesia-centred Syzygium is notably diverse on New Caledonia, with ca 70 species there (see Biffin et al. 2006 for a phylogeny).
Overall, a shift in speciation rates in Myrtaceae has been provisionally placed around the K/P boundary in stem Myrtoideae (Berger et al. 2015), although its exact position and cause(s) remained somewhat unclear. The increasing aridity of the Oligocene-Miocene may have led to the rapid divergence of major clades within the family (Wilson 2011). The shift to fleshy fruits in Syzygieae and Myrteae seems to have been accompanied by increased diversification rates (Biffin et al. 2010a).
Heteropyxidoideae join other examples in the family of species-poor geographically restricted taxa that are sister to much more diverse clades (Lucas et al. 2007; Thornhill et al. 2015; Vasconcelos et al. 2017). Sytsma et al. (2004) suggested that Psiloxylon may have been hopping around on islands in the Indian Ocean for almost 40 Ma (see also Berger et al. 2015: ca 10 My; Thornhill et al. 2015). Heteropyxis apparently lacks terpenes (Mohammed et al. 2009). Heteropyxideae are perhaps most similar to Myrtoideae-Leptospermeae; both wood anatomy (e.g. bordered pits) and pollen are like those of Myrtoideae (Stern & Brizicky 1958). The stamens have separate traces and the androecium shows no signs of being fasciated.
Ecology & Physiology. Most of the family, ca 4,600 species, are trees (= single stem >2 m tall, or if >2 stems, one erect stem >5 cm d.b.h.), the third highest number after Fabaceae and Rubiaceae, but proportionally a higher number than in those families (Beech et al. 2017). Although Myrtaceae have notably many species with stems at least 10 cm across in the Amazonian tree flora, individual species seem never to be locally common (ter Steege et al. 2013), overall, the family is the sixth most abundant in Amazonia (Cardoso et al. 2017).
Closely related species of Eugenia from Barro Colorado island, along with Inga, Piper, Burseraceae, Psychotria, etc., growing as swarms of ecologically similar species in LTRF, also drier forests, show considerable differences in their foliar secondary chemistry, the differences being implicated in defence against herbivores (Sedio et al. 2017). Along the same lines, Vasconcelos et al. (2018) found little floral variation in Myrcia s.l., but again, there was variation in chemistry , etc..
There are around 1,600 Australian species of Myrtaceae, including ca 800 species of Eucalyptus and friends (Crisp et al. 2011a); Eucalyptus s.l. in particular dominates over 90% of the fire-dependent savannas, woodlands and forests there (Lawler & Foley 2002), although Thornhill et al. (2019) suggest that it began its rise to dominance only ca 20 Ma. Species of Eucalyptus, with their epicormic buds, volatile oils, open canopies, bark shedding in large amounts, etc., can be thought of as fire-promoting plants (Keith 2012; Grootemaat et al. 2017: comparison of leaf and bark decomposability, flammability, etc.), but they themselves survive these fires. This is because about 90% of Eucalyptus s.l. species have epicormic strands in their bark, meristematic strands up to several centimetres long, and although they do not often have organised buds, resprouting occurs from the strands after even quite severe fires; they are also associated with the development of additional axillary buds in the young stems (Burrows 2013, and references); Eucalyptus may also have lignotubers. Resprouting after fire happens in many species of Eucalyptus s.l. (but not in e.g. E. regnans) as well as in some other Australian Myrtaceae - importantly, it occurs in the canopy (Burrows 2002; Burrows et al. 2010). Crisp et al. (2011a: 95% HPD) link the evolution of these epicormic strands/buds with biome evolution in Australia some (62-)62, 60(-58) Ma, vegetation dominated by the highly flammable Eucalyptus originated then (dates for crown-group Eucalypteae in Thornhill et al. 2012 are a little younger - (66.2-)60, 55.3(-50.9) Ma). For fire in Australia, see Bradstock et al. (2012), Bowman et al. (2012), Carpenter et al. (2015, 2016, also Hill & Jordan 2016; c.f. in part Bond & Scott 2010). Biomass accumulation in eucalypt woodlands can be great. Average figures of 1,867 tonnes C ha-1 living and dead biomass have been recorded for Eucalyptus regnans-dominated forests (Keith et al. 2009), but the highest values are ca 1,000 tons more - that is why they make such a good bonfire. Eucalyptus-dominated savanna responds differently to fire than do other savannas, since in the latter woody species with epicormic buds are vanishingly uncommon (Moncrieff et al. 2016), and Australian Eucalyptus-dominated savanna is also distinctive becase eucalypts tend to be tall and with narrow crowns compared to trees in savannas elsewhere (Moncrieff et al. 2014). For more on fire and Myrtaceae, see Lamont et al. (2018b). Note that crown-group diversification of the Australian Banksia (Proteaceae), many of which are also fire-associated (see also below), is also quite early (e.g. He et al. 2011; Lamont et al. 2018b); Proteaceae are late Cretaceous in age.
As mentioned above, eucalypt woodland was once geographically more widespread, occurring along with palms in New Zealand at the end of the Early Miocene (Pole 2003) and in Patagonian South America in the early Eocene ca 52 Ma (Hermsen et al. 2012), and its subsequent disappearance in those places may be because climates became wetter (Crisp et al. 2011a). Interestingly, González-Orozco et al. (2016) found that areas of Australia currently harbouring palaeo-endemic species of the Eucalyptus group were particularly likely to shift or even disappear as the climate warms. Eucalypts growing in arid environments have thick leaf blades with apparently overly-closely spaced veins ca 24 mm mm-2, i.e., the distance between veins is less that the distance between veins and stomata (de Boer et al. 2016; c.f. Zwieniecki & Boyce 2014). This may enable such leaves to achieve maximum photosynthatic rates very soon after rain falls; these leaves are also amphistomatous (de Boer et al. 2016). For the possible ecological significance of juvenile/adult differences in leaf morphology (= heteroblasty) in eucalypts, see Vlasveld et al. (2018).
Dry-fruited Myrtoideae, including Melaleuca and Eucalyptus, also species of the fleshy-fruited Syzygium, are often ectomycorrhizal (e.g. Chilvers & Pryor 1965; Smith & Read 1997; Adams et al. 2006; Tedersoo et al. 2008; Bâ et al. 2011a; Laliberté et al. 2015; see also Moyersoen et al. 2001; Brundrett 2017a). These plants are especially abundant in Australia, but although Brundrett (2009) estimated that 1,800 species may be involved, little is known about the eco-physiological dimensions of these associations and the role that they might play in the ecological dominance of Myrtaceae in parts of Australia.
Nine species of Eucalyptus, not immediately related to one another, along with Pinales and a few Dipterocarpaceae, include the majority of giant trees (trees >70 m tall) known (Tng et al. 2012). The giant eucalypts may be an odd sort of rain forest pioneer. They usually depend on fire for their regeneration, and several of them are seeders rather than resprouters; rain-forest trees later move in under the eucalypt canopy, which is not very dense (Tng et al. 2012). Eucalyptus regnans is one of these giant trees and it has a very narrow canopy, much light penetrates, and there is a well-developed understory.
Osbornia is a mangrove plant of the somewhat eastern part of the Malesian tropics.
Pollination Biology & Seed Dispersal. In many Myrtaceae the numerous stamens with their white or brightly coloured filaments are the main visual attractant for the pollinator, and in taxa such as Callistemon (= Melaleuca), the bottle-brush, the flowers of the one inflorescences all open simultaneously. Many Myrtaceae have such brush-type inflorescences, not that dissimilar functionally from the large polystaminate flowers of Eucalyptus s.l.. Calothamnus (also = Melaleuca) has similarly aggregated flowers in which the stamen fascicles form flattened structures, the individual flowers being more or less monosymmetric (Westerkamp & Claßen-Bockhoff 2007), Verticordia has elaborately-fringed sepals - and sometimes also petals and staminodes, and some species of Darwinia have coloured inflorescence bracts. The anther glands (see e.g. Beardsell et al. 1993; Landrum & Bonilla 1996) produce oils which may attract pollinators, but these oils also help in the attachment of pollen to stylar hairs, as in the secondary pollen presentation devices of Verticordia and a number of other Australian taxa of the Chamaelaucium alliance (Slater & Beardsall 1991; Howell et al. 1993; Ladd et al. 1999).
Some 320 or more species of Myrtaceae in Australia may be pollinated by birds, especially by lorikeets (ca 1/2 of Eucalyptus s.l., perhaps 40 species of Melaleuca, some Darwinia, etc.: Ford et al. 1979; Beardsell et al. 1993), and both pollen and nectar may be rewards (Stiles 1981 and references). Bee pollination is common, especially in South American Myrteae, where meliponines in particular collect pollen from Myrcia, and they and other bees are the major pollinators of the unspecialized but mass flowering Myrteae that are common there (Gressler et al. 2006; Vasconcelos et al. 2018). Interestingly, night-flying bees are reported to be the polinators of Campomanesia and some species of Eugenia in South America (Cordeiro et al. 2019). Bee pollination also occurs in a number of Australian Myrtaceae, including Syzygium, and there Colletidae-Euryglossinae are notable pollinators (Beardsell et al. 1993; Nic Lughadha & Proença 1996; Biffin et al. 2010a). Comparison of New World (= many of the old Myrtoideae) and Australian taxa (= many of the old Leptospermoideae) is interesting, since in the former the flowers often last for only a single day, nectar is not often produced, the stigmas are dry, bird pollination is uncommon, etc., while in the latter the flowers can be quite long-lived, nectar is often produced, the stigmas are wet, and bird pollination is quite common (c.f. Nic Lughadha & Proença 1996 and Beardsell et al. 1993). Metrosideros polymorpha from Hawai'i is a very important nectar source for birds there, however, it is estimated that the genus has been on the islands for a rather short time, perhaps (6-)3.9 Ma (Percy et al. 2008) or ca 3.1 Ma (Dupuis et al. 2020), and the birds have been around for longer than that. In the South American Myrrhinium (close to Psidium) pollination is by frugivorous birds that visit the flowers to eat their fleshy petals (Roitman et al. 1997; Nadra et al. 2018). For summaries of pollination in Western Australian Myrtaceae, see Keighery (1982), and for honeyeaters, etc., obtaining carbohydrates from sources along the stems of plants like Eucalyptus, see Plant-Animal Interactions below.
The berry-like fruits common in Myrtaceae, especially in Myrteae and Syzygieae (unrelated), are commonly dispersed by bats (Muscarella & Fleming 2008), monkeys and especially birds (Gressler et al. 2006). The fruits are an important food resource for small animals in the New World in particular, and Myrtaceae in the Brazilian Atlantic Forest vary considerably both in basic fruit morphology and in fruiting times (Galan et al. 2016; Staggemeir et al. 2017, 2015b and references: phenological patterns in Myrteae). Wind dispersal is also common, if only over short distances, thus Booth (2017) reviewed the extensive literature bearing on seed dispersal in the capsular-fruited Eucalyptus and found that dispersal probably averaged only 1-2 m/year. See also Beardsell et al. (1993) and Nic Lughadha and Proença (1996) for seed dispersal.
Plant-Animal Interactions. Myrtoideae are noted for the amount and diversity of the terpenes that they produce (Keszei et al. 2010), and these compounds were thought to be involved in defence against herbivores (Lawler & Foley 2002). Thus the monoterpenoid 1-8-cineole, antimicrobial and an insecticide, is apparently a major component of the essential oil of Eucalyptus (Hendry et al. 2009; Pichersky & Raguso 2018). However, at least some of the terpenes may be involved in signalling, a variety of formylated phloroglucinol compounds, for the most part biosynthetically unrelated to terpenes, being involved in herbivore deterrence (B. D. Moore et al. 2004). For similar systems, see Inga, Piper, Protium, etc., Passiflora, sundry Solanaceae and Psychotria.
About half the galls on Australian plants have been recorded from Myrtaceae (Mani 1964). Thus Eriococcidae (scale insects) are widely distributed on Eucalyptus and other members of the family (Gullan et al. 2005). Another set of galls are found on species of Eucalyptus s.l. as well as other unrelated largely Australian Myrtaceae such as Syzygium, Melaleuca and the like - a few Myrtaceae from India to New Zealand are also involved. These genera are part of a three-way mutualistic association that involves the plant, the actual gall-former, the nematode Fergusobia (see Ye et al. 2007; Davies et al. 2010 for phylogenies, etc.), and the dipteran Fergusonina. The nematode parasitises Fergusonina for part of its life cycle and is responsible for gall formation while the fly larvae determine the internal structure of the gall; nematodes without fly larvae and vice versa do not survive, indeed, the female fly carries the nematode to new sites (Taylor et al. 2005; Nelson et al. 2014; Scheffer et al. 2017). Although the relationship is often 1:1:1, deep cospeciation appears not to be involved, the stem age of Fergusoninidae being around 42 Ma, much younger than the ages of its hosts, however, lower-level cospeciation is possible (Nelson et al. 2014); around 3/4 of the flies are restricted to a single host plant species, and all to a single host genus (Scheffer et al. 2017). Little more than the outline of this fascinating tritrophic association is currently understood, and there may be several hundred different fly-nematode associations (Nelson et al. 2014) - around 170 species of flies is a number derived from figures in Scheffer et al. (2017: p. 151), with one plant species hosting up to eight Fergusonina species.
Larvae of 90 or more species of a family of sawflies, Pergidae, eat Eucalyptus, far more species than are found on non-myrtaceous/rainforest plants (Schmidt & Walter 2014). Rainforests, at least, are where species-poor clades of the family are to be found, and radiation of two clades on eucalypts is dated to to the Palaeocene, roughly the time that eucalypts themselves were diversifying (Schmidt & Walter 2014; see also above). Tortricine moths (Epitymbiini) larvae feed on Myrtaceae leaf litter in Australia, and some other moth groups are also foliovores on this family (Powell et al. 1999). Some 150+ species of the moth Pectinivalva, leaf miners belonging to the monotrysian Nepticulidae, and with a few other genera making up an Australian clade, are known only from Myrtaceae (Doorenweerd et al. 2016). For the insects that eat Metrosideros on Hawai'i, which has quite recently moved there, perhaps only ca 3.1 Ma (Dupuis et al. 2020), see Gruner (2004).
An often overlooked set of plant-animal interactions occurs between nectarivorous birds like honeyeaters, etc., and eucalypts (and other taxa). The birds may acquire substantial amounts of carbohydrates from the plant, either as manna (rate of removal by New Holland honeyeaters, e.g. 9.1 blobs/minute), which is dried exudates from wounds, as honeydew, produced by young aphids, etc., and/or as lerp, the protective covering of psyllids (Paton 1980). Such carbohydrate complements that acquired from other sources, including flowers; importantly, birds apparently looking for insects to eat as they probe eucalyptus bark may well be looking for these nectar sources (Paton 1980). As discussed elsewhere (end of the linked section), oscine birds, a major group of Passeriformes, initially radiated in Australasia, and they can taste sweetness; there is perhaps a connection between early oscine diversification and the evolution of Myrtaceae and Eucalyptus.
For the gut biota of koala bears, which eat nothing but Eucalyptus leaves, and its possible role in dealing with the secondary metabolites of that plant, see Shiffman et al. (2017: zoo animals, bacterial family S24-7 abundant in all koalas, c.f. p. 20). Johnson et al. (2018) discuss the possible genetic basis for the koala's ability to tolerate levels of toxins in eucalypt leaves that would be lethal to most other mammals.
Bacterial/Fungal Associations. Dry-fruited Myrtoideae from Australia, including Melaleuca and Eucalyptus, are often ectomycorrhizal (ECM) or ECM-arbuscular mycorrhizal (AM) (e.g. Chilvers & Pryor 1965; Smith & Read 1997; Adjoud-Sadadou & Halli-Hargas 2000; Tedersoo et al. 2008; Bâ et al. 2011a; Kariman et al. 2012; Teste & Laliberté 2018; see also Brundrett 2017a; Tedersoo 2017b; Tedersoo & Brundrett 2017 for literature, ages, etc.). The beneficial effects of ECM fungi are particularly strong in Myrtaceae, the boletes Pisolithus and Scleroderma being particularly evident (Hoeksema et al. 2019: meta-analysis). Adams et al. (2006) note that younger plants of Eucalyptus are more likely to be AM, the mature plant becoming ECM. Similar ECM fungi grow on Nothofagaceae and Myrtaceae, both southern groups, perhaps because ECM fungi moved from Nothofagaceae on to Myrtaceae as the climate became drier in the Tertiary (Tedersoo et al. 2008, 2014a). Basal clades of the ECM false truffle group Hysterangiales are found predominantly on Australian Myrtaceae (Mesopelliaceae grow on Eucalyptus) (Hosaka et al. 2008). Vellinga et al. (2009) discuss introductions of ECM fungi in general, over a quarter of which have been on Myrtaceae/Eucalyptus. Bacterial mycorrhization helpers are known for both ecto- and endomycorrhizal Eucalyptus (Duponnois & Plenchette 2003).
Genes & Genomes. A genome duplication, the SYMIα event ca 44.7 Ma, has been reported (Landis et al. 2018: Syzy Euc). For cytology, see Rye (1979) and Costa and Forni-Martins (2007 and references).
Economic Importance. For Eucalyptus s.l., now very widely grown for its timber and essential oils, see Coppen (2002).
Chemistry, Morphology, etc.. For polyhydroxyalkaloid distribution (pyrrolizidine, pyrrolidine, and piperidine alkaloids), see Porter et al. (2000); they occur both in Psiloxylon and in some Myrtoideae. A number of Myrtoideae produce gums s.l. (these have been called kinos - Lambert et al. 2007b, 2013) and especially terpenes (Keszei et al. 2010), while some have high silica content in their leaves (Westbrook et al. 2009). The Eucalyptus group is rich in tannins, especially ellagic acid, and as elsewhere there is an inverse correlation between the production of hydroyzable tannins/ellagitannins and condensed tannins/proanthocyanidins; there is a correlation of tannin chemistry and phylogeny (Marsh et al. 2017: comprehensive survey); cyanogenesis occurs in Eucalyptus (Hansen et al. 2018).
Vestured pits are common in dry-fruited Myrtoideae (?Syzygium as well) (Carlquist 2017b). Lid cells are distinctive epidermal cells covering oil glands that i.a. can be used to recognise fossil Myrtaceae (Lange 1980). There is considerable variation in stomatal morphology in Myrtoideae (Tarran et al. 2018 and references: esp. App. S1B); cyclostaurocytic stomata have four or more cells more or less radially arranged around the stomata. Tarran et al. (2018) also discuss the distribution of eglandular hairs in the family. Da Silva et al. (2012) noted that there was a diversity of colleter morphologies, although they did not record any colleters from Eucalypteae; see Pimentel et al. (2014) for colleters in the flowers.
Floral development has been much studied. Perianth parts (calyx and/or corolla) of a number of Eucalyptus and some other taxa may be undifferentiated and/or variously fused into a calyptra or operculum (e.g. Pryor & Knox 1971; Drinnan & Ladiges 1989a, b; Bohte & Drinnan 2005); circumscissile abscission of the hypanthium/calyptra occurs in various ways. The development of the corolla in Angophora in particular is complex. There is an abaxial more or less apiculate keel supplied by a largely unbranched vascular bundle and an adaxial corolline portion which can be more or less connate (e.g. Drinnan & Ladiges 1988). There may also be a calyptrate calyx in , and the corolla has also been described as being calyptrate, althouth here free petals surround the rest of the flowers and fall off as a unit (). Vasconcelos et al. (2019a) summarized the extensive floral variation in Myrteae (some species are dimerous, there may be a hypanthium, the calyx may be calyptrate, the filaments straight or incurved, and so on). Androecial variation is extreme, even between quite closely-related taxa. Syzygieae also have a calyptra, either made up of a connate calyx, or a morphologically quite distinct structure, the petals all falling together although they are not connate at all... (Vasconcelos et al. 2019b).
The androecium shows much variation and its morphology can be difficult to characterise. As Orlovich et al. (1996: p. 716) noted, "In both Lophostemon and Xanthostemon, polyandry is beyond the concepts of haplostemony and diplostemony in both their ontogenetic and phylogenetic senses." Taxa with a fasciculate androecium often have a prestaminal bulge, and the distribution of stamens around the circumference of the flower is also affected by differential expansion of the hypanthium, stamens tending to mass opposite the calyx or corolla (e.g. Orlovich et al. 1996; Belham & Orlovich 2003). Flowers with apparently oppositisepalous stamens are developmentally derived from an oppositipetalous androecium (see e.g. Carrucan & Drinnan 2000; Drinnan & Carrucan 2005), and fasciculate and non-fasciculate androecia intergrade (Orlovich et al. 1999). In some species of Eucalyptus the androecium is displaced, arising from a stemonophore, the base of the corolla limb, or development may be more conventional (see e.g. Drinnan & Ladiges 1989a, b, 1991). Thornhill and Crisp (2012) discuss pollen evolution in the family. Microsporogenesis in some Eucalyptus may take six months (Beardsell et al. 1993).
L. A. S. Johnson and Briggs (1984) emphasized the fully superior nature of the ovary in Heteropyxidoideae (= their Psiloxylaceae), with its relatively narrow base, comparing it with the more or less inferior ovary of Myrtoideae (Myrtaceae), which always had a broad base. Pimentel et al. (2014; see Martos et al. 2017 for more on floral development of Myrteae) suggest that the inferior ovary in Myrteae may be either appendicular or receptacular (also the placentae may be cauline or carpellary), while Harthman et al. (2018) suggest that the distinction between axile and parietal placentation is not that sharp. There is considerable variation in ovule morphology and orientation, the latter even on the one placenta (Bohte & Drinnan 2005), and the parietal tissue varies greatly in thickness, being very thick in Eugenia (van Wyk & Botha 1984) and Eucalyptus s.l. (Bohte & Drinnan 2005). Corner (1976) described the micropyle as being exostomal; it is variable, but perhaps most commonly bistomal.
Seed coat anatomy (see also ovules) and embryo vary greatly, and testa anatomy correlates with fruit type: capsular fruits tend to have exotestal seeds; baccate fruits have seeds with a generally sclerotic testa (c.f. Nic Lughadha & Proença 1996 and Beardsell et al. 1993; see also Gauba & Pryor 1961 and references: Eucalyptus s.l.; van Wyk & Botha 1984; Biffin et al. 2006). There is commonly a more or less elaborated/swollen basal portion of the hypocotyl that bears root hairs, however, in Angophora a broad, disc-like structure (= coleorhiza) in the same position lacks such hairs (Baranov 1957).
For general information, see Schmid (1980) and especially Wilson (2011), also Blake (1977: Allosyncarpia et al.), Van Wyk (in Dahlgren & Van Wyk 1988: Heteropyxis), McKinnon et al. (2008: Eucalyptus and immediate relatives), Parnell et al. (2007: Syzygium s.l.), also Keszei et al. (2008: terpenes, Australian Myrtaceae), Soh and Parnell (2011: Sysygium) and Cardoso et al. (2009: Brazilian Myrtoideae) both lamina anatomy, Brooker and Nicolle (2013: venation and oil glands), for inflorescence structure of Myrtoideae, see Briggs and Johnson (1979), for floral development, see Belsham and Olovich (2003), Drinnan et al. (2001) and Orlovich et al. (1996), for filament curvature in Myrteae, see Vasconcelos et al. (2015: correlation with major clades), for pollen, see Thornhill et al. (2012b and references: comprehensive), and for embryology, in which there is considerable variation, see Mauritzon (1939a: integuments in bitegmic ovules consistently 2 cells across), Narayanaswami and Roy (1960 and references), Prakash (1969: Darwinia) and references in Bohte and Drinnan (2005), also see van Wyk and Botha (1984: seed coat, etc., Eugenia) and van Wyk et al. (1980: cork cambium initiation) and other papers by van Wyk and collaborators.
Phylogeny. Conti et al. (1996) found a well supported [Heteropyxidaceae + Psiloxylaceae] sister to [Myrtaceae + Vochysiaceae]; note, however, that the pollen grains of the first two are similar to those of Myrtaceae (Dahlgren & Thorne 1985). Monophyly of Myrtaceae s. str. (= Myrtoideae) was not strong (Conti et al. 1996, 1998). However, Wilson et al. (2005: matK only) found Myrtaceae s. str. to have 80% jacknife support, while [[Heteropyxidaceae + Psiloxylaceae] + Myrtaceae s. str.] (all together = Myrtaceae here) had ³95% support; a similar set of relationships were found by Sytsma et al. (2004: matK and ndhF) and Maurin et al. (2021: nuclear genomes).
The old Myrtoideae, capsular-fruited, are paraphyletic (Sytsma et al. 1998; Wilson et al. 2001; Salywon et al. 2002), while fleshy-fruited taxa (Myrteae) are largely derived and monophyletic, although the large genus Syzygium s.l., Syzygieae, represents an independent acquisition of fleshy fruits (see also L. A. S. Johnson & Briggs 1984); for relationships in these plants, see also Biffin et al. (2010a). The limits of major clades (= tribes) in Myrtoideae are similar in Wilson et al. (2005: matK) and Biffin et al. (2007: ITS), but the relationships between the clades are less so, although the differences are poorly supported. Vasconcelos et al. (2017) found relationshiups around Myrteae to be [[Leptospermeae + Eucalypteae - outgroup] [Syzygium [Metrosideros [Xanthomyrtus (Tristanieae) [Myrtastrum and other Myrteae]]]]].
Within Myrtoideae as currently delimited, Maurin et al. (2021) found relationships that differed depending on the particular analysis of Angiosperms353 data. Although [Lophostemoneae + Xanthostemoneae] were consistently sister to the rest of the subfamily, the topology then seems to revolve around Melaleuceae (probably plus Osbornieae). In exon coalescent ASTRAL analyses Myrteae, Lysicarpus, etc., formed a clade above Melaleuceae, and Chamaeleucieae, Leptospermeae, etc., formed a clade below; these two clades switched positions while largely retaining the same internal relationships in exon RAxML supermatrix and coalescent supercontig ASTRAL analyses - although support values were in general poor (Maurin et al. 2021).Tribal limits and internal relationships suggested by Maurin et al. (2021: q.v. for details) do sometimes differ (and they may vary between analyses); only some of their findings are mentioned here. Note that they found Kanieae were polyphyletic, with Kania separate from the rest of the tribe. Relationships around Eucalypteae may be [Syncarpieae [Syzygieae [Lindsayomyrteae + Eucalypteae]]] (Maurin et al. 2021) - clade size varies greatly.
Chamelaucieae. Rye et al. (2020: 1 nuclear, 2 choroplast markers) provide an extensive phylogenetic analysis of the tribe.
Eucalypteae. Phylogenetic relationships around Eucalyptus s.l. have been much discussed, e.g. by Byrne (2008), Parra-O. et al. (2009), Steane et al. (2011), Bayly et al. (2013a: chloroplast genomes), Rutherford et al. (2016), Jones et al. (2016: much low-level hybridization, species polyphyly, etc.), González-Orozco et al. (2016: esp Extended Data Figs 6, 7), Healey et al. (2018: chloroplast capture between quite separate taxa), and Thornhill et al. (2019). Ochieng et al. (2007) recovered the monophyly of Corymbia using nrITS pseudogene sequences, corroborating relationships using morphology, microsatellites, etc., however, González-Orozco et al. (2016) found that Angophora was nested within Corymbia, although support was not strong, while within Eucalyptus, Symphyomyrtus was paraphyletic. Indeed, the position of Corymbia with respect to Angophora seems particularly uncertain (Schuster et al. 2018; Thornhill et al. 2019; Maurin et al. 2021), and within Corymbia morphology and nrDNA tell one story, chloroplasts another - here, as in Eucalyptus itself, hybridization and chloroplast introgression rather than lineage sorting seem to be involved (Schuster et al. 2018). Series and sections in both Corymbia and Eucalyptus are not monophyletic (Thornhill et al. 2019).
Melaleuceae, another predominantly Australian group, are strongly supported as being monophyletic. The three main clades making it up have high posterior probabilities but only moderate to low bootstrap support; most of the small genera previously recognised in this tribe fall into one of these clades, along with a group of species of Melaleuca s. str. (Edwards et al. 2010; see also Brown et al. 2001).
Metrosidereae: Wright et al. (2000a), Pillon et al. (2015) and especially Dupuis et al. (2020) evaluate relationships in the largely East Malesian-Pacific Metrosideros, still poorly understood but which has been expanded to include taxa from South America (Tepualia) and New Caledonia. Dupuis et al. (2020) found that M. laurifolia, from New Caledonia, was sister to the rest of the genus.
Myrteae. Vasconcelos et al. (2017) found that Myrteae included three major clades, [Australasian [ [Myrtus group + Main Neotropical Lineage]], but the relationships between the three were somewhat unclear as was the position of the New Caledonian Myrtastrum rufopunctatum; the latter could be sister to all the rest of the tribe (Vasconcelos et al. 2017). Amorim et al. (2019) suggested the relationships [paraphyletic Blepharocalyx [Myrtus group [PAM clade = Myrceugenia group [Plinia group + Myrcia s.l.]]]]. For relationships in Myrceugenia and its immediate relatives like Blepharocalyx, etc., see Murillo-A et al. (2012, 2013). The fleshy-fruited Myrcia s. str. is strongly paraphyletic and forms a large clade with i.a. Calyptranthes (Lucas et al. 2011, also Wilson et al. 2016; Santos et al. 2016; Vasconcelos et al. 2016), while Marlierea, which it also includes, is notably polyphyletic (Staggemeier et al. 2015a). There have been 9 usually well-supported major clades (= sections) within Myrcia in its broad sense (Lucas et al. 2011; Santos et al. 2017), and another clade was added by Amorim et al. (2019); see also Lima et al. (2021: section Aguava). Mazine et al. (2014, 2018, see also Mazine Capelo et al. 2011; Bernardini et al. 2014) have begun the task of disentangling relationships in the largely New World Eugenia; it initially appeared that there were two major clades in the genus, but more detailed analyses suggest a rather more pectinate structure, albeit support for some nodes tends to be rather weak. Within the large persistently bracteolate clade the Old World section Jossinia is sister to the rest. Van der Merwe (2005) discuss relationships in Eugenia, mostly African, de Lange et al. (2010) provide a phylogeny of the Antipodean Kunzea. Flickinger et al. (2020) take a broad look at Myrteae in the Greater Antilles. Maurin et al. (2021) sampled Myrteae quite extensively, and they found that the odd New Caledonian Myrtastrum rufopunctatum is sister to the clade that contains all Neotropical species.
Syzygieae. Eugenia (connate cotyledons, especially New World) and Syzygium (free cotyledons, Old World) were confused in the past; the two are not immediately related (see Schmid 1972 for a pre-molecular resolution of the problem). After disentangling the two, the relationships of Syzygium to genera like Acmena had to be worked out (Harrington & Gadek 2004: ?rooting). As Biffin et al. (2006, see also Biffin & Craven 2011) found, Acmena and Waterhousea are in a well supported clade along with Syzygium s. str., while the poorly supported sister clades to this group are also largely made up of species of Syzygium.
Classification. Myrtaceae s. str. (excluding Heteropyxidoideae) were traditionally divided into Leptospermoideae - leaves spiral to opposite; fruit dry, dehiscent - and Myrtoideae - polyhydroxyalkaloids common; leaves opposite; terpenoid-containing glands in the apex of the connective, stigma dry; fruit fleshy, indehiscent. This distinction is untenable (see above). For a classification of Myrtoideae in which 15 tribes are recognized, see P. G. Wilson et al. (2005) and Wilson (2011). Rye et al. (2020) divided Chamelaucieae into 11 subtribes, mostly new. However,
Generic limits in Myrteae have been problematic (Lucas et al. 2005, 2007; Wilson 2011), but see Vasconcelos et al. (2017) and in particular Lucas et al. (2019) for genera and a subtribal classification, te former pointing out a number of para- and polyphyletic genera. Thus the limits of and infrageneric groupings within Myrcia/Calyptranthes have needed attention (Lucas et al. 2011; Wilson et al. 2016). Indeed, Myrcia, paraphyletic, is to be expanded and to include Marlierea and Calyptranthes, genera based on characters of the calyx that have turned out to be homoplastic (Staggemeier et al. 2015a; Vasconcelos et al. 2016). Lucas et al. (2018) provide a sectional classification of Myrcia. Mazine et al. (2016, 2018) provide an infrageneric classification of Eugenia, the majority of species being placed in section Umbellatae; note that the limits of Neotropical Eugenia are best expanded (Mazine Capelo et al. 2011 for a summary). Biffin et al. (2006; see also Craven 2001; Biffin et al. 2007; Biffin & Craven 2011) suggest that Syzygium should be delimited broadly, at least pending a better understanding of the morphological variation of this clade; an infrageneric classification needed to be put in place, although some of the groups were difficult to recognise - but that of course would be true if Syzygium were split up and they were recognised as genera. Craven and Biffin (2010) provide an infrageneric classification, although since 80-90% of the species belong to subg. Syzygium, within which relationships are poorly understood, there is still plenty to do! Eucalyptus may be in the process of being dismembered (Parra-O. et al. 2009 and references); for a classification of the eucalypts, see Nicolle (2015). The disposition of Corymbia has not been settled; include it in the same genus as Angophora, or separate it and recognise more genera (Schuster et al. 2018 for earlier nomenclatural arguments in the Australian eucalypt community; Thornhill et al. 2019)? The limits of Melalauca are being expanded; if genera were segregated they would both be small and undiagnosable, distinctive characters being highly homoplastic in the group (Edwards et al. 2010). Generic limits in Chamelaucieae are in a state of flux (Rye 2015 and references).
Govaerts et al. (2008) provide a world checklist of Myrtaceae.
Botanical Trivia. Eucalyptus regnans, the snow gum, is the tallest known angiosperm, although in mass it is much less than Sequoia or Sequoiadendron (Cupressaceae). It may grow up to 101 m (ca 330 feet) tall, however, before the logging of the last century and a half there may have been individuals substantially over 400 feet tall (Carder 1995).
Thanks. I am grateful to Z. Rogers for discussion about Heteropyxis.
[Melastomataceae [Crypteroniaceae [Alzataeaceae + Penaeaceae]]]: plants Al accumulators; fibre tracheids +; (nodes swollen); branched or unbranched sclereids +/0 within same family; C clawed?; connective abaxially much expanded; endothecial thickening absent/atypical; nectary 0; exotestal cells ± longitudinally elongated.
Age. Estimates of the age of this node are (99-)91(-82) Ma (Berger et al. 2015), ca 84 Ma (Morley & Dick 2003), ca 82 Ma (Sytsma et al. 2004), about 80 Ma (Renner et al. 2001), about 68.1/65.4 Ma (Tank et al. 2015: Table S1, S2) or (107.6-)94(-80.4 Ma (Gonçalves et al. 2020a).
Evolution: Divergence & Distribution. Endothecium evolution may be more complex than simply scoring its absence as an apomorphy for the clade might imply (e.g. Cortez et al. 2014; see esp. Melastomataceae).
Chemistry, Morphology, etc.. A number of taxa, but apparently not Melastomataceae, have more than a single branch from the leaf axil. Nodes other than simple unilacunar are quite widespread, however, a survey of nodal anatomy, particularly that of Melastomataceae, is much needed.
The anther connective is least expanded in Penaeaceae-Rhynchocalyx.
Phylogeny. For relationships in this area, see Conti et al. (2002).
MELASTOMATACEAE Jussieu, nom. cons. - Back to Myrtales
Trees or shrubs; (plants Al-accumulators); veinlets with terminal sclereids; leaves with 2 or 4 strong secondary veins, from (near) the base [acrodrmous - ?exact position]; K quincuncial, C contorted [right-handed]; A = 2 x K, anthers with branched vascular trace [?all]; stigma punctate; micropyle zig-zag, outer and inner integuments ca 2 cells across; radicle bent; x = 11 (?10), nuclear genome [1 C] (0.038-)0.829(-18.202) pg.
Ca 188 [list]/4,960. Very largely tropical, also subtropical, 70% New World (Veranso-Libalah et al. 2018). Two main groups below, tribal characterizations in Melastomatoideae and generic synonymy under development.
Age. Renner et al. (2001, also Renner & Meyer 2001) suggested that crown group diversification began about 53 Ma and Wikström et al. (2001) offered the somewhat younger age of (51-)47, 41(-37) Ma, Morley and Dick (2003) suggested the substantially older date of ca 82 Ma; dates suggested by Bell et al. (2010) are (65-)48, 41(-28) Ma, while Systma et al. (2004) suggested an age of ca 56 Ma, Berger et al. (2015) an age (75-)64.5(-56) Ma, Gonçalves et al. (2020a) an age of (80.4-)66.7(-53.6) Ma, Reginato et al. (2020) an age of (77.3-)63.4(-56.1) Ma, X.-F. Zhang et al. (2021) an age of (71.5-)45.8(-13.7) Ma and Amarasinghe et al. (2021) an age of (85.9-)77.1(-67.5) Ma.
[Kibessioideae + Olisbeoideae]: included phloem +; anthers dehiscing by pores/slits; strong development of differential growth in the flower [see Chemistry, Morphology, etc.]; G opposite C.
1. Kibessioideae Naudin
Small trees; also included phloem in multiseriate rays; crystal styloids +, large; cork cambium superficial; petiole bundle arcuate; stomata anomo-cyclocytic; hairs uniseriate; leaves triplinerved; inflorescence axillary, flowers 4-merous; K connate, cupuliform/truncate; endothecium restricted to inner wall of inner sporangium only, connective thickened, spur near the filaments (0); G placentation parietal, ovary divided by septae; ovules many/carpel; capsule fleshy, surface setose/umbonate-tesselate-echinate; seeds small; n = ?
1/20: Pternandra. India, S. China, N.E. Australia, most Malesia. Map: based on Maxwell (1981: incomplete).
Age. Crown-group Kibessioideae are (16.7-)9.9(-4.4) Ma (Reginato et al. 2020).
2. Olisbeoideae Burnett
Vessel ray pits half bordered; crystal styloids +, large; (nodes 1:3); sclereids at node and base of petiole (etc.); foliar sclereids/?fibres at ends of veinlets, + (0); small crystal styloids + (0); petiole bundle arcuate, annular; (leaf veins lacking fibrous sheath); stomata anomo-/paracytic, (in crypts - many Mouriri); plant usu. glabrous, (hairs uniseriate); stem apex frequently aborting, branching (complex) from previous flush; lamina vernation flat [Memecylon] or revolute [Mouriri], secondary veins pinnate (pli-nerved); inflorescence often fasciculate, pedicels articulated; flowers small, 4-5-merous; (K imbricate), (truncate), C (protective in bud - most Memecylon), often asymmetrical [scalloped/fringed on one side]; A (straight in bud - Votomita), anther endothecium + [cells thickened all around]; placentation various [basal/parietal/axile/free-central, 2- or 4-locular], stigma wet; ovules 1-14(-many)/carpel, ± campylotropous, apotropous, funicle 0, (outer integument 4-6 cells across - Mouriri), parietal tissue ca 3 cells across; fruit a berry; seeds large, 1-5(-12), testa (multiplicative), (some sclerotic hypodermal exotestal cells: Memecylon), exotegmen fibrous, massively sclerotic subhilum; embryo large (small), green, cotyledons large, thick, (± crumpled - Memecylon); n = 7; seedling hypocotyl elongated or not, cotyledons lobed, stipules +.
6/485: Memecylon (405), Mouriri (85). Tropical. Map: from Morley (1976: Fig. 1), Schatz (2001) and Trop. Afr. Fl. Pl. Ecol. Distr. 1 (2003). [Photo - Flower, Fruit.]
Age. Crown-group Olisbeoideae are (44.9-)31.3(-20.1) Ma (Reginato et al. 2020), while Amarasinghe et al. (2021) estimated that the Memecylon + Mouriri clade was ca 44.4 Ma.
Synonymy: Memecylaceae Candolle, Mouririaceae Gardner
2. Melastomatoideae Seringe
Acylated anthocyanins +; anthocyanins in the root tip; libriform fibres +, vessel-ray pits simple; included phloem 0; (nodes 1:3; split laterals); cortical (and medullary) bundles +; leaf veins lacking fibrous sheath; lamina vernation conduplicate or supervolute, venation acrodromous, tertiary veins at right angles to the midrib, stipules 0; G developing before A; flowers ± monosymmetric [by the androecium]; K open [?level], (with adaxial [= Vorläuferspitze] and abaxial lobes); heteranthy common, anthers opening by pores, epidermis persisting, endothecium 0, 3 middle layers of wall with thickened cells, connective with a basal appendage or not; tapetal cells uninucleate; pollen 3-colporoidate; G opposite K, often spaces between ovary wall and hypanthial tube, style impressed; ovule micropyle zig-zag, outer integument (2-)3(-4) cells across, inner integument 2(-3) cells across, parietal tissue 2-7 cells across, ?nucellar cap +, ?endothelium +, hypostase +: embryo sac long and thin, curved or not;; fruit dehiscing down its inferior part (capsule); seeds small, many, with hilar operculum, radicle in testal pocket, exotesta palisade to cuboid, lignified, (sclerotic mesotesta +), tegmen crushed; cotyledons often unequal, incumbent; n = (8-)9(-)12(-)17 (23, 31), chromosomes 0.5-3 μm long.
181/4,455. Largely tropical and subtropical, esp. South America, Colombia and Brazil diverse, ca 400 spp. endemic to the Caribbean alone. Map: from Trop. Afr. Fl. Pl. Ecol. Distr. vol. 1 (2003), Quian and Ricklefs (2004), FloraBase (consulted 2007) and Woodgyer (2007). Photo:Flower, Fruit, Fruit.
Age. Crown-group Melastomatoideae are (72.0-)58.9(-47.3) Ma (Reginato et al. 2020).
Fossil leaves identified as Melastomatoideae have been found in Palaeocene deposits 60-58 Ma from Central Colombia (Carvalho et al. 2021b).
[Henrietteeae + Astronieae]: large styloids in lamina.
Age. The age of this clade is (36.1-)23.6(-12.9) Ma (Reginato et al. 2020).
2. Henrietteeae Penneys, Michelangeli, Judd & Almeda
Woody; medullary and cortical vascular bundles 0; (lamina margin serrate); inflorescence various, fasciculate, flowers axillary; K calyptrate to valvate; fruit a berry; n = 15, 20, 28.
3/77: Henriettea (67). South Mexico to Bolivia and Brazil, the Caribbean.
Age. Henrietteeae are (17.4-)12.9(-8.4) Ma (Reginato et al. 2020).
2. Astronieae Triana
Shrubs to trees; petiole bundle complex, open; stomata mostly anomocytic; indumentum as peltate scales; (anthers opening by slits); carpels opposite petals; placentation basal to basal-axile.
4/150: Astronidium (70), Astronia (60). Indomalesia and Pacific, Tessmannianthus American.
Age. Crown-group Astronieae are (12.1-)8.0(-4.7) Ma (Reginato et al. 2020).
[Lithobieae [Blakeeae [[Merianeae [Eriocnemeae + Miconieae]] [[Eriocnemeae + Miconieae] [[Bertolineae + Sonerileae] [[Trioleneae + Cyphostyleae] [[Cambessedesieae + Dissochaeteae] [Pedoconnective Clade]]]]]]: ?
2. Lithobieae Penneys & Almeda
Rosulate herbs, tuberous rhizome; medullary vascular bundles +; stomata various; flowers single, long-pedicellate, ?axillary; flowers polysymmetric, 3(-4)-merous; teeth external to K 0; anthers uniporose; fruit loculicidal capsule; seeds smooth; n = ?
1/1: Lithobium cordatum. Brazil, Minas Gerais.
[Blakeeae [[Merianeae [Eriocnemeae + Miconieae]] [[Eriocnemeae + Miconieae] [[Bertolineae + Sonerileae] [[Trioleneae + Cyphostyleae] [[Cambessedesieae + Dissochaeteae] [Pedoconnective Clade]]]]]]: ?
2. Blakeeae Bentham & J. D. Hooker
Shrubs to trees, lianas, hemiepiphytes, epiphytes; inflorescence axillary, cymose/flowers single or fascicles, bracteoles 4(6); flowers usu. 6-merous, monosymmetric or not; K with external projections/calyptrate, no projections, valvate (imbricate); fruit baccate; n = ?
2/190: Blakea (180). Mexico (Chiapas) to Bolivia and Brazil, Lesser Antilles, Jamaica.
Age. Crown-group Blakeeae are (9.5-)6.5(-3.7) Ma (Reginato et al. 2020).
Synonymy: Blakeaceae Barnhart
[[Merianeae [Eriocnemeae + Miconieae]] [[Eriocnemeae + Miconieae] [[Bertolineae + Sonerileae] [[Trioleneae + Cyphostyleae] [[Cambessedesieae + Dissochaeteae] [Pedoconnective Clade]]]]]]: ?
[Merianeae [Eriocnemeae + Miconieae]]: ?
Age. Note that Reginato et al. (2020) dated the clade including Octhephilus, then thought to be in Eriocnemeae, and Physeterostemon, also Eriocnemeae, at (12.5-)8.2(-3.8) Ma; the former genus is now placed in Merianeae by et al. (2021).
2. Merianieae Triana
Plant herbaceous/shrubby (lianes; roots from internodal areas); (hairs with subulate cells, ± mesifixed); (outer integument ca 3 cells across); capsule triangular.
Meriana (75), Graffenrieda (44).
Age. Crown-group Merianeae are some (28.5-)21.4(-15.3) Ma (Reginato et al. 2020).
[[Eriocnemeae + Miconieae] [[Bertolineae + Sonerileae] [[Trioleneae + Cyphostyleae] [[Cambessedesieae + Dissochaeteae] [Pedoconnective Clade]]]]]: ?
[Eriocnemeae + Miconieae]: medullary vascular bundles +.
Age. The age of this clade is around (18.8-)13.3(-8.9) Ma (Reginato et al. 2020) - note that these authors dated the clade that included Octhephilus, then thought to be in Eriocnemeae and Physeterostemon, also Eriocnemeae, at (12.5-)8.2(-3.8) Ma; the former genus is now placed in Merianeae by Maurin et al. (2021).
2. Eriocnemeae Penneys & Almeida
Herbs to shrubs; druses +; ?stomata; inflorescences terminal; flowers poly/monosymmetric; external K teeth +; anthers uniporose; fruit loculicidal capsule; testa smooth.
2/7: Physeterostemon (5). S.E. and N.E. Brazil.
2. Miconieae de Candolle
Nodes 1:1; inflorescences terminal/axillary; K (calyptrate); A (many), anther connective elaboration slight/0, (glands on connective at base of thecae); G (superior), (-21), (placentae linear/branched); outer integument (2)/3(-7) cells across/(multiplicative); fruit baccate; n = 17.
3/1,900: Miconia (inc. Clidemia, Conostegia, Leandra, etc.). Tropical America, the Antilles, 1 sp. West Africa.
Age. Crown-group Miconieae are estimated to be (15.8-)11.3(-7.4) Ma (Reginato et al. 2020).
Synonymy: Miconiaceae Martius
[[Bertolineae + Sonerileae] [[ Trioleneae + Cyphostyleae] [Cambessedesieae + Dissochaeteae] [Pedoconnective Clade]]]: ?
[Bertolonieae + Sonerileae]: capsule triangular
2. Bertolonieae Triana
Rhizomatous herbs, (epiphytes); stomata anisocytic (diacytic); inflorescence scorpioid; A monomorphic, anther appendages dorsal; G [3(-4)], subinferior; capsule enveloped by K.
1/32: Bertolonia. S.E. Brazil.
Age. Crown-group Bertolineae are some (20.3-)11.6(-4.6) Ma (Reginato et al. 2020).
2. Sonerileae Triana
Herbs (shrubs); (inter-vessel pits +, scalariform); cortical and medullary bundles 0; (raphides +); glandular hairs sessile or stalked; stomata anisocytic; (anisophylly + [extreme]); lamina (margin serrulate); inflorescence ?scorpioid; (flowers 3-, 4-merous); A (isomorphic), (= and opposite K); G almost superior to inferior, (with apical annulus [= "crown"]); capsule (not triangular).
?17/528: Sonerila (?180), Gravesia (105). Tropical, esp. Old World.
Age. The crown-group age of Sonerileae is estimated to be (29.3-)21.7(-14.6) Ma (Veranso-Libalah et al. 2018) or (33.1-)25.4(-18.8) Ma (Reginato et al. 2020).
Note: Medinilla and immediate relatives, ex-Dissochaeteae and with about 420 species, belongs somewhere around here.
[[Cyphostyleae + Trioleneae] [Dissochaeteae + Cambessedesieae] [Pedoconnective Clade]]]: ?
[Trioleneae + Cyphostyleae]: ?
2. Trioleneae Bacci, Michelangeli & R. Goldenberg
Herbs; inflorescence scorpioid; K with abaxial subulate teeth; A dimorphic, appendages 1-3, ventral; capsules triangular, surrounded by K; n = ?
2/43. Mexico south to Peru and adjacent Bolivia, western Amazonia.
Age. Crown-group Triolaeneae are (32.4-)22.1(-12.4) Ma (Reginato et al. 2020).
2. Cyphostyleae Gleason
(Herbs); (lamina venation pinnate); K calyptrate (not - Quipuanthus); A 5, opposite K; G inferior; fruit dry, breaking apart when seeds are released, (capsular); n = ?
4/21. Inter-Andean valleys from Colombia to Peru.
Age. The crown-group age of this clade is (21.5-)>14.2(-7.1) Ma (Reginato et al. 2020).
[Dissochaeteae + Cambessedesieae] [Pedoconnective Clade]]]: ?
Age. Ages for taxa in the clade [Medinilla [Rhexia + Tibouchina]] in Rutschmann et al. (2004) were around 111.7-25.3 Ma, depending on fossil calibrations and analytic techniques used.
[Cambessedesieae + Dissochaeteae]: ?
2. Cambessedesieae Bochorny, Almeda, Michelangeli & R. Goldenberg
Shrubs (trees, lianas); flowers (6-7 merous); hypanthium (apically constricted); A (not heteranthous), appendages 0, dorso-basal, linear/2, bilobed; G superior-inferior, [2-5(-6)]; fruit a capsule; seeds pyramidal/oblong (winged); n = ?
3/68: Huberia (37), Cambessedesia (25). Brazil, esp. E., N.E., and centre, few in Andean Ecuador and Peru.
Age. Crown-group Cambessedesieae are (34.8-)26.6(-18.8) Ma (Reginato et al. 2020).
2. Dissochaeteae Triana
Plants epiphytes, (root climbers, scramblers); (?anomalous secondary thickening + [wood deeply 4-several lobed]); indumentum stellate/bristles; leaves anisophyllous (extremely so), with massive interpetiolar stipuliform structures; flowers 4-merous; K free to connate and truncate; A 8/4 + 4 staminodes/4 opposite K/4 opposite C; G (8-locular); fruit baccate.
6/93: Dissochaeta (40). Bhutan and Hainan to New Britain.
Age. Crown-group Dissochaeteae are (26.5-)17.5(-10.3) Ma (Veranso-Libalah et al. 2018) or (37.3-)28.5(-19.0) Ma (Reginato et al. 2020).
Age. This clade is (37-)28.3(-20.3) Ma (Veranso-Libalah et al. 2018).
Pedoconnective Clade / [Rupestrea, Rhexieae, Microlicieae [Marcetieae + Melastomateae]]: pedoconnective + [sterile anther base].
2. Rupestrea Goldenberg et al.
K conspicuous; G semi-inferior; ovules 1/carpel; fruit indehiscent; seed cochleate, "orthocampylotropous"; n = ?
1/2. Atlantic Forest, Bahia, Brazil.
[Rhexieae, Microlicieae [Marcetieae + Melastomateae]]: ?
Dinophora and Ochthocharis, ex-Dissochaeteae, belong somewhere around here.
2. Rhexieae de Candolle
Seeds cochleate, surface complexly costate-tuberculate.
/18. Southeast USA to the Antilles.
Age. Divergence within Rhexieae started (40.8-)32.3(-23.3) Ma (Veranso-Libalah et al. 2018) or (25.0-)22.2(-20.1) Ma (Reginato et al. 2020).
Synonymy: Rhexiaceae Dumortier
2. Microlicieae Naudin
Cortical vascular bundles +; petiole bundles, 3-7, arcuate, in a line, (7, amphicribral, incurved C-shaped arrangement); lamina often amphistomatous, palisade tissue isobifacial; K not conspicuous; anthers (polysporangiate, septae parenchymatous); seeds oblong-reniform, surface foveolate.
7/275-300: Microlicia (170). South America, mainly Brazil, also Bolivia; drier and more open environments.
Age. The crown-group age of this clade is 19-16 Ma (Fritsch et al. 2004), (34-)25.2(-17.2) Ma (Veranso-Libalah et al. 2018) or (22.7-)16.0(-9.3) Ma (Reginato et al. 2020).
[Marcetieae + Melastomateae]]: ?
Age. This clade is some (36.9-)31.1(-26.0) Ma (Reginato et al. 2020).
2. Marcetieae da Rocha, Guimaraes & Michelangeli
Annual or perennial herbs to subshrubs (trees); flowers 4(-5)-merous; A 2 x C (=, antesepalous whorl), (anthers straight), pedoconnective long, bipartite; G [2-4], ovary glabrous; outer integument ca 3 cells across fruit a capsule; seeds mostly cochleate to reniform.
19/122: Marcetia (30), Siphanthera (15). Mexico and the Antilles to Argentina.
Age. Crown-group Marcetieae are (32.1-)26.3(-20.1) Ma (Reginato et al. 2020).
2. Melastomateae Bartling
(Interxylary phloem + - Dissotis); large styloids in lamina [Centradenia]; (stipuliform structures + - Tibouchina); (flower terminal, solitary - Cailliella); intersepalar appendages +; K lobes caducous; A isomorphic, ventral appendage linear; seeds cochleate, surface tuberculate, hilar operculum round.
50/870: Tibouchina (245), Pleroma (157), Chaetogastra (117), Brachyotum (55), Melastoma (50). drier and more open environments.
Age. Crown-group Melastomateae are (36-)29.2(-23) Ma (Veranso-Libalah et al. 2018, q.v. for other dates in this area) or (30.4-)24.9(-19.2) Ma (Reginato et al. 2020).
Evolution: Divergence & Distribution. The topology of the tree in Reginato et al. (2020), and the taxa examined in the tribes recognized, should be compared with subsequent topologies for the family.
Renner et al. (2001, also Renner & Meyer 2001) thought that there was little substantial diversification within Melastomataceae until ca 30 Ma, and movement into Africa occurred still more recently some ca (18-)14(-10) Ma. Morley and Dick (2003), on the other hand, were inclined to think that the broad outlines of diversification in the family could be linked with major tectonic (drift) events, and there was much diversification, including the separation of the African/Malagasy clades, before ca 68 Ma, roughly when Madagascar and India separated. Clearly, these are incompatible scenarios. Renner (2004a, b) again suggested that dispersal, not drift, was more likely, with separate Miocene dispersal events resulting in the species found on Madagascar, for example. Berger et al. (2015) date a shift in speciation rates in the family to after the divergence of Kibessieae, which they date to around 64 Ma, and place this in South America.
The North American Rhexia - well, North American now - occurs fossil (as the distinctive seeds) throughout Eurasia in the Caenozoic (Michelangeli et al. 2012 and references), which has important implications for both dating and biogeographical scenarios.
Melastomataceae s.l. are centred in the New World tropics where some 70% of the family is to be found (with approaching 700 species, they are the fourth most diverse family in Amazonia - Cardoso et al. 2017), and there is a fair bit of geographical structuring of the major clades (see Reginato & Michelangeli 2015). Basal in the largely Old World Sonerileae are New World genera (Wurdack & Michelangeli 2019). Columbia alone has one third of the species and Brazil one half (Almeda et al. 2009). In Brazil, some 580 species (14% of the whole family), largely in nine major clades, are to be found in the Atlantic Forest (Michelangeli et al. 2015). 200 species of Microlicieae alone have radiated into the fire-prone Cerrado, diversification of Microlicia, etc., occurring within the last (ca 14-)9.8(-ca 6) Ma (Simon et al. 2009) or ca 3.7 Ma Fritsch et al. 2004, 2007), and other melastomes also grow there. Nearly all of the ca 215 species of Leandra are from eastern Brazil (Reginato & Michelangeli 2015). Bécquer-Granados et al. (2008) and Michelangeli et al. (2008b) discuss the complex biogeography of the speciose Antillean melastomes, while Goldenberg et al. (2008) find substantial geographical signal correlating with major clades in Miconia and its relatives - common in the family (e.g. Penneys & Judd 2005; Michelangeli et al. 2008b, 2012, 2013). A clade of Memecylon from wstern and central Africa is sister to the rest of the genus (Stone 2014), similarly, Amarasinghe et al. (2021) found two small African clades sister to the rest of the genus; Memecylon is particularly diverse in Madagascar, where there are about 140 species, many of which are very localized (Stone 2012; 96 species, all endemic, Amarasinghe et al. (2021); other Melastomataceae are to be found in l.t.r.f. on Madagascar, and they have an overall high level of endemism (Muasya et al. 2011).
It has been suggested that buzz-pollinated Melastomataceae and their pollinators are trapped on an adaptive peak or plateau (e.g. Berger et al. 2015; Dellinger et al. 2018: see also Solanaceae, Malpighiaceae), but in terms of allowing overall diversification the trap would seem to be quite pleasant. Furthermore, Dellinger et al. (2019a) found that in Merianeae, despite the presence of long-tubular porose anthers characteristic of buzz-pollinated flowers throughout the tribe, there have been two shifts to pollination by passerines in particular (see Dellinger et al. 2014 for the complex mechanisms evolved) and two to pollination by vertebrates more generally. Heteranthy and associated features of the flower have been interpreted in the context of the "pollen dilemma", the pollen being needed both by the plant for pollination and by the pollinator for food (e.g. Westerkamp 1996; Velloso et al. 2018). For floral evolution in Leandra, see Reginato and Michelangeli (2016).
Abiotic dispersal is plesiomorphic in the family, while biotic dispersal has arisen some eighteen times and in both the Old and New Worlds and perhaps in association with passerine radiations, but there has also been reversals to abiotic dispersal (Reginato et al. 2020). Within Melastomatoideae, capsular fruits are associated with superior ovaries and fleshy fruits with inferior ovaries, although this is not an absolute correlation (e.g. Clausing et al. 2000; Basso-Alves et al. 2017a). There is no particular association between dispersal mode and diversification shifts, the latter appearing to be rther idiosyncratic (Reginato et al. 2020).
For wood anatomy and phylogeny, see van Vliet et al. (1981).
Ecology & Physiology. Melastomatoideae in particular are an important component of the understory vegetation of tropical forests, especially in the New World; in Amazonian forests they are represented by a large number of species with stems at least 10 cm across, but none is common (ter Steege et al. 2013). Species are also quite often early successional, and apomixis was more common in pioneers or invasives (dos Santos et al. 2012). For variegation in the leaves of taxa growing on the forest floor, see Y.-S. Chen et al. (2017). Epiphytes are quite common in Melastomatoideae, also in Ericaceae, another woody group, Piperaceae and Gesneriaceae in broad-leaved angiosperms, and also Orchidaceae and Bromeliaceae. These include ca 300 species or more in the palaeotropical Medinilla (unplaced). In the New World a 1986 estimate was that ca 230 species were obligate or facultative epiphytes, these were particularly common in montane habitats, interestingly, obligate epiphytes, ca 85% of the total, have fleshy fruits (Renner 1986; Clausing et al. 2000). New World epiphytic melastomes may have distinctive anatomical traits that can be connected with water stress, but they do not have CAM photosynthesis (Ocampo & Almeida 2013b). Some species are scramblers, whether with hook-shaped roots, or climbing by roots that attach directly to the support; some of the latter taxa show extreme heterophylly, with pseudo-2-ranked leaves, one leaf of each pair being much reduced (see Zeigler 1925; Clausing & Renner 2001a; Gamba-Moreno & Almeida 2014 for anisophylly). Bacci et al. (2019) noted that herbaceous taxa tended to have angled fruits.
The family is overwhelmingly mesophytic. However, many Microlicieae are adapted to the seasonally dry and fire-prone Cerrado vegatation of Brazil where they are a major clade, although Fritsch et al. (2004) noted that Rhynchanthera, which prefers rather more mesic conditions, was sister to other members of the family that they examined (see also) Simon et al. 2009; de Carmo et al. 2020: anatomy). Some other melastomes grow in the Cerrado, and much diversification in this species-rich habitat has been within the last 5 Ma or so (Simon et al. 2009). Furthermore, ca 12 shifts to open habitats have occurred in African Melastomateae alone since the middle Miocene (Veranso-Libalah et al. 2018).
Pollination Biology & Seed Dispersal. Monosymmetry of the flower is most evident in the androecium, and the stamens, often distinctively different in colour from the petals, may form a serried rank on one side of the flower. The petals of Melastomatoideae are usually more or less widely spreading, and buzz pollination is common, flowers being visited by females of many species of bees in search of pollen, for which the flowers are an important polen resource (Renner 1989; Harter et al. 2002; Melo et al. 2021). Heteranthy (differences in shape between stamens of the one flower) and stamen dimetrism (size differences) are also common; these conditions represent extremes of a continuum (c.f. Melo et al. 2021: Fig. 1). The flowers are usually nectarless, and stamen dimetrism is less pronounced when rewards are other than pollen (Melo et al. 2021). In Dissochaeta the anthers of oppositipetalous stamens provide feeding pollen for the bees, while pollen from the oppositipetalous stamens is involved in actual pollination (Kartonegoro et al. 2018). Pollen from stamens differing in morphology may differ in fertility, and in at least some cases it is the less fertile pollen that is more likely to be collected by the bee (Luo et al. 2008), or there may be more pollen in the pollinating oppositipetalous stamens (Velloso et al. 2018; see also Melo et al. 2021). Different species of bees tend to visit different melastomes, although the bees involved are not oligolectic; thus mass-flowering Miconia cinerascens in Brazil is visited by the stingless Melipona (Harter et al. 2002) which also visits other plants. Goldenberg et al. (2008) suggest quite complex relationships between anther morphology and pollinator in Miconia and relatives, and in Andean Miconia, not only has there been independent evolution of broader anther pores, but also white anthers (from variously coloured), dioecy, and polysymmetric flowers (Burke et al. 2012). For more on buzz pollination, see Dellinger et al. (2019c), for anther dehiscence see Cortez et al. (2014).
Within Merianeae three quite distinct bee pollination syndromes could be recognised, varying in characters specific to Merianeae rather than in classical pollination syndrome-type characters (although all three syndromes had porose anthers), and there were also "mixed vertebrate" and "passerine" syndromes (Dellinger et al. 2018). Transition away from buzz pollination involves changes in how the pollen is released and in the rewards offered to the pollinator (Dellinger et al. 2018), and has been thought of as an escape from specialization (de Brito et al. 2016). Parts of the flower other than the tubular anthers (constraint) evolved more quickly; the flower as a whole was no evolving, but functional modules within it were (Dellinger et al. 2019b). Some Melastomataceae have nectariferous anther connectives, the nectar exuding through cracks in the tissue, or more commonly through stomata (e.g. Blakea, Penneys & Judd 2013b), or nectar is produced on the corolla (Medinilla), hypanthium, or even on the stigma or on top of the ovary (some Miconia) - again, nectarostomata are generally involved (Varassin et al. 2008). In such cases the contorted petals, although free, do not reflex and so form a tube, and the anthers often open by longitudinal slits (although lacking an endothecium?), and pollination is likely to be by birds and perhaps rodents (Renner 1989; Stein & Tobe 1989; Vogel 1997; Varassin et al. 2007, esp. 2008; Penneys & Judd 2013b). Pollination by tanagers has recently been demonstrated in Axinaea where the birds eat a sucrose-rich appendage on the anthers which also acts as bellows, pollen being puffed out the anther pores and dusting the the bird's head at the same time (Dellinger et al. 2014). Axinaea grows at 1000-3600 m in the Andes, and some other Melastomataceae, mostly from higher altitudes, have adopted vertebrate pollination and they produce nectar as a reward (Varassin et al. 2008; Dellinger et al. 2014 and references; Brito et al. 2016; de Brito et al. 2017). There is bird pollination in Blakea, pollination being explosive here, the pollen being discharged when the anthers are touched (Wester et al. 2016). Flowers of Miconia sect. Cremanium, whose stomatiferous anthers have broad pores, are visited by a variety of pollinators, and here generalist pollination is derived from more specialized buzz pollination (Kriebel & Zumbado 2014). In Miconieae as a whole generalist pollination, involving flies, has evolved several times from specialist pollination, involving wasps and/or bees alone. Generalist pollination is linked with short anthers, large anther aperture, nectar as a reward, altitude, and also with seed size, flowers pollinated by generalists tending to have fruits with fewer, larger seeds (Brito et al. 2016, 2017). However, in some species of Meriana at least, pollination seems to be bimodal rather than generalized, that is, flowers are adapted to pollination by separate functional groups of pollinators, here hummingbirds/bats, hummingbirds/rodents and flower piercers/rodents (Dellinger et al. 2019a, b). There is sequential flowering of different species of Melastomataceae at the one locality - Miconia on Trinidad (Snow 1965); see Hosaka et al. (2016) for sequential flowering in general.
In many Olisbeoideae oil is the reward for the pollinator, and genera of Centridini, Exomalopsini, Euglossini and Tetrapedini collect exudate from the oil-producing anther glands, also collecting pollen by buzz pollination. Flowers with these glands (the great majority of species) are blue, rarely yellow, flowers without them are white (Buchmann & Buchmann 1981; Buchmann 1987), however, there is much infraspecific variability in flower colour (Morley 1976). Amarasinghe et al. (2021) discuss cauliflory, pollination and fruit dispersal in Memecylon.
Apomixis/polyembryony is common in Melastomatoideae from Cerrado and Campo Rupestre vegetation types in Brazil, where it has been found in about one third of the species; apomixis was more common in the widely-distributed species (dos Santos et al. 2012; Rodrigues & Oliveira 2012). In Miconieae, apomictic species were little visited by pollinators (Brito et al. 2016); they total ca 70% of the whole tribe (Caetano et al. 2018; Melo et al. 2021 and references). For apomixis and also hybridization in Leandra, see Reginato and Michelangeli (2015).
Within Melastomatoideae, capsular fruits are often associated with superior ovaries and fleshy fruits with inferior ovaries (e.g. Clausing et al. 2000; Basso-Alves et al. 2017a). Throughout the Neotropics fruits of Melastomatoideae are a major resource for frugivorous birds, smaller species in particular (Stone 1981; Messeder et al. 2020). Thus fleshy fruits of Miconieae in the Colombian Andes comprise about 11.5% by weight of fleshy fruits but ca 32% of all fruit eaten by birds (Kessler-Rios & Kattan 2012). Taxa with fleshy fruits and small seeds are much eaten by tanagers, which, being "mashers", tend to remove seeds more than 2 mm long before swallowing the fruit, while manakins, "gulpers", eat fruits with larger seeds and gulp the fruit whole; both groups of birds are restricted to the New World (Stiles & Rosselli 1993; see also Renner 1986). There seems to be no particular correlation between the thickness of the outer integument and the fleshiness of the fruit (Caetano et al. 2017). Messeder et al. (2020) built up a database of animals that ate New World Miconia, and they suggested that the genus was a significant food source for 13% of all Neotropical birds and 70% of the primary frugivores - not to mention mammals, especially primates, reptiles, fish and ants, the latter attracted to the fruit pulp (no arils) as well as being granivores. Thus Land (1983) recorded 23 species of birds eating fruits of a tree of Miconia trinervis in Guatemala. Such birds tend to be rather small, while species of Miconia, notably common in secondary forest, produce many small fruits with numerous small seeds (Snow 1971). Species of Miconia have evolved to fruit at different times of the year (Messeder et al. 2020), and Snow (1965) emphasised that this happened in the rather equable climate of Trinidad. (Messeder et al. 2020: p. 589) "emphasize the role of Miconia in providing consistent and reliable food resources to frugivores over the years, as well as being one of the plant taxa most likely to sustain many animal species during periods of food scarcity in seasonal ecosystems [but see above] throughout the Neotropics". A comparison they make is with Ficus (Moraceae) which, along with Cecropia (Urticaceae), is another particularly important resource for frugivorous birds and other animals. In Old World Malesian forests sugar-rich fruits of the largely aseasonally-fruiting Melastomatoideae in the understorey are an important food source for birds (Leighton & Leighton 1983), for example, Melastoma has fruits which dehisce to expose mounds of small seeds with fleshy testas that are eaten by birds. Olisbeoideae also have fleshy fruits, but with fewer and larger seeds.
In the New World, taxa with dry fruit tend be commoner at higher altitudes and in savannas and more seasonal forests (Stiles & Rosselli 1993). A few taxa with dry, dehiscent fruits do have inferior ovaries, and there the outer fruit wall may fall away, the fruit proper then functioning as an ordinary capsule (Michelangeli et al. 2008a); a group of these genera form a clade (Michelangeli et al. 2011: they also have stamens opposite the sepals). Indeed, the ripe fruit, that is, a capsule, the product of the superior ovary, may be completely surrounded by the persistent hypanthium, and this has occasioned the description of several fruit "types" (Bacci et al. 2019 and references). Splash-cup dispersal is known from a few Melastomataceae that are forest herbs, and in some vivipary is also recorded, seeds that are not dispersed germinating in the capsule (Bacci et al. 2021).
Plant-Animal Interactions. Clidemia heterophylla and species of Tococa like T. guianensis in western Amazonia live in close association with the ant Myrmelachista which creates mono- or oligospecific "devil's gardens" by injecting formic acid into the leaves of the surrounding vegetation, which is thus suppressed; the ant colonies may be 1-2 million strong (Morawetz et al. 1992; Davidson & McKey 1993; McKey & Davidson 1993; Frederickson et al. 2005; Salas-Lopez et al. 2014). Bacteria living off colony debris in Tococa may be eaten by rhabditid nematodes that are possibly in turn eaten by the ants (Maschwitz et al. 2016). Petiolar or laminar ant domatia are quite common in Blakeeae and Miconieae; in Maieta guianensis (Miconieae) ca 80% of the host plant's nitrogen is derived from the waste deposited by the ant Pheidole minutula that lives in the domatia (Solano & Dejean 2004). Other ants, small in size, may live between the long, dense hairs covering the plant - in some eight neotropical genera, for instance (Davidson & McKey 1993). Chomicki and Renner (2015: fig. S10) estimate that there may have been eight gains of myrmecophily in Miconieae alone, and almost as many losses.
Widespread and sometimes very extensive damage to anthers of Brazilian Melastomataceae can be caused by pollen-robbing Trigona bees (Renner 1983).
Bacterial/Fungal Associations. Graffenrieda emarginata, frequent on fungus-rich ridges in southern Ecuador, forms associations with both ecto- and endomycorrhizal fungi (Haug et al. 2004).
Chemistry, Morphology, etc.. The roots have anthocyanins. Poay et al. (2011) described galloylated cyanogenic glucosides from Phyllogathis. For wood anatomy, see van Vliet et al. (1981); vessel:ray pits are simple. Within Olisbeoideae, vessel:ray pits are half bordered, and the rays are 2-5 cells wide and heterocellular, compared to 1(-4) cells wide and homocellular elsewhere in this clade. For foliar sclereids, common in Olisbeoideae, see Rao (1957, 1983); they are associated with the endings of the veinlets, and some span the width of the lamina. A survey of nodal anatomy is needed; split laterals are probably quite common (pers. obs., see also R. A. Howard in van Vliet & Baas 1975), and cortical bundles may run along the raised angles of the stem. In genera like Dissochaeta and Pternandra there can be prominent interpetiolar flanges even below the leaves, while in Meriania nobilis the flange forms a large-cup-shaped structure at the node (?anatomy). Vernation may seem to be plicate because the secondary veins are so prominent; the leaves of Mouriri remain folded as they elongate.
The floral vasculature of Mouriri is distinctive (Morley 1953, 1976), with strong differential growth in the inferior ovary resulting in the branching points of the main carpel bundles being as it were drawn upwards and outwards - variation in placentation in Mouriri is extreme. It is as if the central part of the flower (the stylar base region) had become depressed, the lower central parts moved laterally, and the outer parts upwards; there may be two vascular bundles suppying each placenta that enter separately from each end (Morley 1953). Kibessioideae also have this kind of floral development, and they do have rather odd placentation, although overall with little variation in placentation, and there may be approaches to this kind of growth in some Melastomatoideae (Morley 1953, see also literature cited). Little is known about floral development, although Wanntorp et al. (2011b) studied that of Conostegia, in which there has been increase in floral meristicy, and some other genera; stamen primordia opposite the petals may split. Basso-Alves et al. (2017b) looked at the development of the remarkable biseriate calyx of Leandra melastomoides, and found that the adaxial/upper/dorsal portion (= a Vorläuferspitze?) was vascularized by the main sepal trace, and the broad, rounded, basal/abaxial/ventral portion was supplied by other branches from the three traces entering each sepal. Similar biseriate calyces are quite common in Melastomatoideae.
Venkatesh (1955) found that the anthers of Memecylon had a normal endothecium, while in those of Mouriri the walls of the cells of the hypodermal layer were thickened all around. In Miconia, at least, the anther epidermis has a thick cuticle, except that in the pore area, which lacks a cuticle (Cortez et al. 2014). The pedoconnective, an extension of the connective between the base of the thecae and the insertion of the anther on the filament, can be quite elaborate. Anthers and anther wall development in Miconia are very diverse, some species having bisporangiate anthers, monocot wall development, crystals in the tapetal cells, etc. (Cortez et al. 2015). Ovary position varies extensively in the family, and Basso-Alves et al. (2017a) studied the formation of the hypanthium (= "perigynous hypanthium", when the floral apex changed from convex to concave) and the development of the inferior ovary (= "gynoecial hypanthium"), largely due to intercalary meristematic activity. For the development and anatomy of the fleshy fruit of Miconia, see Cortez and Carmello-Guerreiro (2008). The seed coat varies considerably, but there seems to be little phylogenetic signal here (Ocampo & Almeda 2013a). The reports of stiples in seedlings of Olisbeoideae need confirmation - are they colleters?
For general information, see Penneys (2004 onwards)
Phylogeny. The clade [Mouriri + Memecylon] is sister to Pternandra, and these are in turn sister to the rest of the family in ndhF trees (Renner 1993); van Tieghem (1891b), Morley (1953, 1976), van Vliet et al. (1981) and others had early suggested this relationship, some characters of wood anatomy agreeing with it, and it was also recovered by Veranso-Libalah (2018: no comment, general relationships not the focus) and by Maurin et al. (2021) in a comprehensive analysis of relationships in Myrtales using nuclear genomes. X.-F. Zhang et al. (2021: plastomes, only one species of Olisbeoideae included) and W. J. Baker et al. (2021a: nuclear genomes, see Seed Plant Tree of Life) also found Pternandra linking with Olisbeoideae - in the latter Oxyspora (Sonerileae!) was sister to the whole family, but with very little support... However, Pternandra has also been found to be sister to all other Melastomatoideae, Astronieae perhaps next (Clausing & Renner 2001b: moderately good support in a 3-gene analysis; Renner 2004b; Wurdack & Michelangeli 2019).
Within Olisbeoideae, Spathandra is probably sister to the large, palaeotropical Memecylon, although support is weak and it sometimes links with the [Votomita + Mouriri] clade, Lijnedia and Warneckia are successively sister to the whole group, although sometimes the two form a single clade (Stone 2006; Stone & Andreasen 2010). All six morphologically-based genera of Olisbeoideae have molecular support (Stone 2006). Within Memecylon, the small African subgenus Mouriroidea was found to be sister to the rest (Stone 2014), although branch lengths along the spine of the phylogeny tended to be short.
Broad studies in neotropical Melastomatoideae in particular over the last decade or so have used largely chloroplast genes to provide an idea of relationships (Guimaraes et al. 2010; Penneys & Judd 2010, esp. 2011: 111 morphological characters; Judd et al. 2010; Wurdack & Michelangeli 2019, etc.). A clade that included Merianieae and Miconieae was stable, and was sister to clade in which Bertolonieae were sister to a group that included Melastomateae, but further relationships there were not entirely stable (Reginato et al. 2016). These relationships are quite similar to those in Michelangeli et al. (2014) and Goldenberg et al. (2015). However, in the latter in particular Henriettieae associated with Astronieae, while the odd genus Rupestrea, there newly described, was strongly supported as being sister to a clade that included Microlicieae, Rhexieae, and Melastomateae, although more detailed relationships within that clade, the pedoconnective clade, were not well supported (Oldenberg et al. 2015); this clade was also recovered by Maurin et al. (2021), who also emphasized the instability of relationships in it. In a quite recent plastome analysis Henriettea (Henriettieae) was sister to the 15 other Melastomatoideae in the study, which represented representatives of most major clades (Reginato et al. 2016). Veranso-Libalah et al. (2018) recovered relationships quite similar to those found by other authors, i.e. [[[Henrietteeae + Astronieae] [Merianeae + Miconieae]] [Blakeeae [[Cambessedesia [Dissochaeteae + Sonerileae]] [Rhexieae ... Melastomateae]]]], and also by Penneys et al (2020), who in some analyses found the relationships [[Henrietteeae + Astronieae] [Lithobium [Merianeae [Eriocnemeae + Miconieae]...]]]. Lithobium (= Lithobieae) tends to move around the tree (Maurin et al. 2021). For Schwackaea, see Kriebel (2016a). Maurin et al. (2021) found that in the Angiosperms353 nuclear analyses the content of the tribes were largely stable, even if some ideas of their relationships and of relationships within them might have to be revised. They also emphasized that Dissochaeteae and Sonerileae were unlikely to be sister taxa - c.f. Veranso-Libalah et al. (2018). Details of relationships in Kartonegoro et al. (2021) are somewhat different from the above, but such relationships were not the focus of their work.
Astronieae. Maurin et al. (2021) found that Tessmannianthus, a small neotropical genus of quite large trees, was sister to other Astronieae, all Old World taxa. Penneys and Judd (2013b) analyzed both molecular and morphological characters in Blakeeae. Dissochaeteae. Relationships in this clade have been clarified by Kartonegoro et al. (2021), and Medinilla, Dinophora and Ochthocharis have been excluded, if at present they are unplaced. Marcetieae are based on some neotropical genera that used to be in Melastomateae; here nodes along the spine tend to have somewhat weak support, but the monophyly of the genera had stronger support (da Rocha et al. 2017). Cambessedesieae. Cambessedia rupestris, Merianthera burlemarxii and Huberia comosa are all sister to the rest of the three genera, but relationships between the genera are not well supported (Bochorny et al. 2019). Michelangeli et al. (2012; see also Renner & Meyer 2001) and especially Guimarães et al. (2020) looked at relationships within the New World Melastomateae (polyphyletic) and Veranso-Libalah et al. (2017, esp. 2018, 2020: Dissotis area) at those within African Melastomateae. For the polyphyletic Leandra, see Martin et al. (2008), for the polyphyletic Tibouchina - at least the old sections usually held together - see Guimarães et al. (2020), and for the African-Madagascan Warneckea, see Stone and Andreasen (2010). Generic limits in Merianeae are difficult (Schulman & Hyvönen 2003). For a phylogeny of the fleshy-fruited, speciose, and paraphyletic Miconia (Miconieae), see Michelangeli et al. (2004), Martin et al. (2008), Majure et al. (2015), Skean et al. (2018); previously delimited genera and sections are not monophyletic, in part because of over-reliance on anther morphology when delimiting taxa (Goldenberg et al. 2008; Burke et al. 2012). Here Pleiochiton and Leandra were recovered as successively sister to other members of the tribe (Maurin et al. 2021). Relationships within Sonerileae are complicated by the extreme polyphyly of Phyllagathis species of which were found in eight of the fourteen clades recovered by Q.-J. Zhou et al. (2019a, see also b), seven taxa of the genus still remained unplaced, and other genera in the tribe were also polyphyletic. Bacci et al. (2019) found that genera like Macrocentrum and Meriana were polyphyletic in their study of the phylogeny of the general Sonerila area (see also Maurin et al. 2021). Within Miconieae, Gamba and Almeida (2014) look at relationships in the Octopleura clade (the old Octopleura/Ossea area), where there were three main groups and much variation in indumentum, ovary position and seed morphology in particular. Goldenberg et al. (2018) examined relationships in section Chaenanthera from the Mata Atlantica, although there seems to have been hybridization here. Judd (1989) and Judd and Skean (1991) provide morphology-based phylogenetic analyses of axillary- and terminal-flowered Miconieae respectively. For relationships in a somewhat expanded Conostegia, see Kriebel et al. (2014: variation in position of major clades, nice morphology, and especially 2016b), and for those in the speciose Leandra, see Reginato and Michelangeli (2015) - and of course these will end up in Miconia. Fritsch et al. (2004) looked at relationships within Microlicieae, where Rhynchanthera was sister to the rest of the tribe.
Classification. The inclusion of Memecylaceae in Melastomataceae was an option in A.P.G. II (2003), and this was formalized in A.P.G. III (2009). However, given the position of Kibessieae either sister to or immediately basal to Memcylaceae/oideae, Maurin et al. (2021) question whether Melastomataceae should be divided into subfamilies - "each of the main clades could be recognized as tribes" (ibid., p. ). If by this is meant that Melastomatoideae could be considered a single tribe, the nomenclatural implications of this would be unfortunate indeed - some formal grouping of clades in Melastomatoideae seems desirable. Indeed, over the last decade or so sampling of New World Melastomatoideae in particular has rapidly been extended and so needed generic and tribal changes are being made - e.g. Penneys et al. (2010: Henrietteeae), Michelangeli et al. (2011: Cyphostyleae), Penneys and Judd (2013a: Blakeeae), Schulman and Hyvönen (2003: Merianeae), Veranso-Libalah et al. (2017, 2020: African Melastomateae, Dissotis pulverized in the latter) and Bochorny et al. (2019: Cambessedesieae, 3 monogeneric tribes vs extended but undiagnosable tribe - the latter option seems reasonable). For genera in Miconieae, see Goldenberg et al. (2008 and references); Majure et al. (2013) discuss the homoplasy of previously-used "generic" characters and argue for a broadly delimited Miconia (see also Majure et al. 2015, 2018; Skean et al. 2018, etc.), and 583 species have recently been transferred to the genus (Michelangeli et al. 2019).
For names in the family, see MEL names (Renner et al. 2007c).
Thanks. I am grateful to S. Renner for comments.
[Crypteroniaceae [Alzateaceae + Penaeaceae]]: vessel-ray and vessel-parenchyma pits half bordered; foliar sclereids +; stipules minute; A = and opposite C; endothecium at most ephemeral; fruit a loculicidal capsule; endotegmen not fibrous.
Age. Renner et al. (2001) thought that this node was only ca 21 Ma, Tank et al. (2015: Table S2) about 39.8 Ma, while Conti et al. (2002: calibration in part based on drift events) estimated it to be 141-106 Ma old. The crown group estimate in Moyle (2004) was (78.6-)68(-57.4) Ma, and that in Morley and Dick (2003) was ca 68 My; ca 52 Ma was the estimate in Sytsma et al. (2004) and (66-)53(-40) Ma that in Berger et al. (2015). Rutschmann et al. (2004) used a variety of analytic methods, and the ages they obtained spanned almost all the others, around (152.6-)109.0-58.9(-35.9) Ma.
Evolution: Divergence & Distribution. Renner et al. (2001) thought that the dispersal was responsible for the distributions of taxa in this clade, while Conti et al. (2002) thought that many of the distribution patterns reflected vicariance events, specifically continental drift (see also Morley & Dick 2003).
Schönenbergerand Conti (2003) discuss the floral evolution of the whole group.
Chemistry, Morphology, etc.. For gross morphology, see van Beusekom-Osinga and van Beusekom (1975). Anatomy is very variable, and van Vliet and Baas (1975) provide detailed comparisons within Myrtales. Laterocytic stomata are known i.a. from Alzatea, Dactylocladus, and Rhynchocalyx (Baranova 1983). For perianth morphology, see Schönenberger and von Balthazar (2006). Details of internal exine structure of Alzatea are similar to those of some Crypteroniaceae; for pollen of much of this group, see J. Muller (1975).
Phylogeny. Some of the relationships within this clade are only weakly supported (see Schönenberger & Conti 2003).
Classification. Van Beusekom-Osinga and van Beusekom (1975) included Alzateaceae and Rhynchocalycaceae in their expanded Crypteroniaceae. However, great expansion was deemed too radical, but Penaeaceae has been moderately broadened to include Oliniaceae and Rhynchocalycaceae (A.P.G. III 2009).
CRYPTERONIACEAE A.-L. de Candolle, nom. cons. - Back to Myrtales
Trees; cork also subepidermal; septate fibres 0, tracheids +, pits bordered; nodes 3:3 [by split laterals], 1:3 with girdling bundles, cortical bundles ± developed or 0; sclereids +/0; petiole bundles annular (with medullary trace) or arcuate, wing bundles +; stomata paracytic (anomocytic - Dactylandra); plant glabrous (hairs unicellular); lamina with secondary veins pinnate to palmate; plant polygamodioecious, or flowers bisexual; inflorescence racemose (spicate), with long branches; flowers 4-5-merous; C 0, 4-5; (A 2x K), connective thickened apically or not; (pollen bisyncolporate); G [2-6], ± inferior, placentation parietal or basal, (transseptal bundles +), style usu. slender, stigma capitate; ovules 1-3 or many [Cryteronia]/carpel, parietal tissue 2 cells across, nucellar tissue disintegrates early, (endothelium + - Axinandra); fruit a capsule, flattened or not, K deciduous; seeds winged, exotestal cells elongated, endotesta crystalliferous, endotegmen tanniniferous, other layers ± degenerate; n = 8, x = ?
3 [list]/10. South East Asia, Malesia, Sri Lanka (map: from van Beusekom-Osinga 1977).
Age. Conti et al. (2002, see also Conti et al. 2004; Rutschmann et al. 2004, esp. 2007) suggested an origin any time from the Early to Late Cretaceous, a later date being favoured (60-45 Ma in Conti et al. 2002). Again, crown-group estimates in Moyle (2004) are much younger (48.6-)39(-29.4) Ma, while those in Rutschmann et al. (2004, see also 2007) were 82.6-17.9 Ma.
Evolution: Divergence & Distribution. Conti et al. (2002, see also Conti et al. 2004; Rutschmann et al. 2004, esp. 2007; Datta-Roy & Karath 2008) suggest that Crypteronia and relatives rafted from Gondwana (Africa) to Asia via India. For Moyle (2004), drift could not be involved.
Plant-Animal Interactions. In West Malesia, at least, there are interactions between Crypteronia, the ant Cladomyrma, and pseudococcid scale insects (Moog 2005).
Chemistry, Morphology, etc.. Some information on Crypteronia and relatives is taken from Tobe and Raven (1983b, 1987b, c) and Renner (2006b: general).
Phylogeny. Dactylocladus is sister to the other two genera, but with only weak support (Conti et al. 2002).
Crypteroniaceae have been included in Melastomataceae in the past (e.g. van Vliet et al. 1981).
Synonymy: Henslowiaceae Lindley
[Alzateaceae + Penaeaceae]: vesturing of pits globular [?level]; septate fibres +, fibre tracheids ?; style stout.
Age. Ages for this node in Rutschmann et al. (2004) were around (135.6-)92.4-53(-26) Ma and in Gonçalves et al. (2020a) (62.7-)36.3(-14.3) Ma.
Chemistry, Morphology, etc.. For vestured pits, see Carlquist (2017a).
ALZATEACEAE S. A. Graham - Back to Myrtales
Trees or shrubs; plants not Al accumulators, myricetin 0; vesturing spread over inside of vessels, vessel-ray and vessel-parenchyma pits simple; branches tending to be several together; nodes 3:3, cortical bundles +; sclereids +; petiole bundle annular and with wing bundles; stipules 0; flowers small, 5(-6)-merous; K pointed in bud, C rudimentary even in bud; anther thecae along apical margin of connective, connective wide, with backwards-directed appendage, filaments short; pollen pseudocolpi 0 (+, faint0; G , placentation intrusive parietal and with an incomplete septum, transseptal bundles +, stigma capitate; ovules many/carpel, micropyle endostomal; megaspore mother cells several, embryo sac bisporic [chalazal dyad], eight-celled [Allium-type]; capsule flattened, K persistent; seeds several, winged all around, with hair-pin bundle; exotestal cells low, with irregularly sinuous anticlinal walls, everything else collapsed; suspensor small; n = 14, x = ?
1 [list]/?2. Costa Rica to Peru (map: see Silverstone-Sopkin & Graham 1986). [Photo - Flowers.]
Evolution: Bacterial/Fungal Associations. Roots of Alzatea verticillata have a considerable variety of mycorrhizal morphologies and mycorrhizal associates, reported to have ectendomycorrhizae, with both a Hartig net and arbuscules formed by a glomeromycote (Peterson 2012 and references), and mucuromycotes have also been found here (Beck et al. 2007).
Chemistry, Morphology, etc.. See S. A. Graham (1985, 2006) for general information on Alzatea.
PENAEACEAE Guillemin - Back to Myrtales
Trees or shrubs; lamina with "glandular" tip; anthers polusporangiate [walls tapetal]; parietal tissue 3-4 cells across; x = 10.
9 [list]/29. E. and S. Africa, overwhelmingly South African, also St Helena. 3 groups below.
1. Rhynchocalyceae Beusekom
Myricetin 0; branches tending to be several together; cork cortical; petiole bundle arcuate, sclereids + [not in stem?]; stipules colleter-like; flowers 6-merous; K pointed, C lobed; A loculi all opening separately, epidermis only persisting; G [2 (3)], placentation parietal, transseptal bundles +, stigma ± punctate; ovules many/carpel, micropyle endostomal, nucellar cap ca 3 cells across; megaspore mother cells several; capsule flattened; seeds several, winged, embryo basal; exotesta tanniniferous, outer wall lignified, exotegmen not fibrous.
1/1: Rhynchocalyx lawsonioides. South Africa, coastal Natal and Transkei.
Synonymy: Rhynchocalycaceae L. A. S. Johnson & B. G. Briggs
[Penaeeae + Olinieae]: plants not Al accumulators; non-hydrolysable tannins +; hypanthium well developed, pollen grains smooth, foot layer and tectum thick; exotegmen fibrous.
2. Penaeeae A. de Candolle
± Ericoid shrublets; tracheids +, with vestured pits; mesophyll with tracheoidal cells and/or ± brached fibres/sclereids; leaves often sessile, lamina (isobifacial), (lacking "glandular" tip), stipules ± colleter-like; flowers axillary, 4-merous; K petal-like, C 0; (connective with branched vascular bundle), (filaments straight in bud); G 4, opposite petals, style also filiform, stigma capitate or lobed; ovules 2-4/carpel, parietal tissue ca 3 calls across, chalazal nucellar region massive; embryo sac tetrasporic, 16-celled [Penaea type]; seeds with funicular elaiosome; exotestal cells much developed or endotestal cells much elongated, other layer crushed, endotegmen fibrous[?]; endosperm pentaploid, chalazal ["basal"] endosperm haustorium +, embryo suspensor 0, hypocotyl massive, cotyledons tiny, root cap 0.
7/23: Stylapterus (8). South Africa, S. and S.W. parts of the Cape. [Photo - Habit.]
Synonymy: Plectroniaceae Hiern
3. Olinieae Horaninow
Cork subepidermal; cyanogenic compounds +; veinlets with terminal sclereids; stomata variable; stipules cauline-on leaf base; flowers (4-)5-merous; ?epicalyx +, small, K ± spatulate, C concave, thick ["scale-like"], hairy; anthers polysporangiate, filaments very short; pollen heteropolar; G [(2-)4-5], opposite sepals, transseptal bundles +, stigma ± clavate, (commissural); ovules 2-10/carpel, apo-/orthotropous, campylotropous, outer integument 3-5 cells across, chalaza strongly vascularized, hypostase +; fruit drupaceous, 1-seeded, K not persisting; exotegmic cells fibrous; "conspicuous suspensor" 0, cotyledons spirally twisted or irregularly folded; n = 12, ?15, ?20.
1/5. Africa, St. Helena. Map: from Coates Palgrave (2002) and Trop. Afr. Fl. Pl. Ecol. Distr. 1. (2003). [Photo - Fruit, Flowers.]
Synonymy: Oliniaceae Harvey & Sonder
Evolution: Divergence & Distribution. Penaeeae are restricted to the Cape Floristic Region (Linder 2003), and the rest of the family has African connections - and with St Helena...
Pollination Biology & Seed Dispersal. Penaeeae often have ant-dsipersed seeds (Lengyel et al. 2010).
Chemistry, Morphology, etc.. The vegetative anatomy of Penaeeae is undistinguished, but their embryo sac is unique. Nectar is secreted from the base of the hypanthium. Crushed or broken plant parts of Olinieae smell of almonds; they contain the cyanogenic glucoside, prunasin. The ovules have been reported as being apotropous and ascending (Baillon 1877). The interpretation of the perianth of Olinia is a matter of some dispute; here I follow Schönenberger and Conti (2003) although the exact nature of the outer whorl of very small appendages is still unclear (described as "?epicalyx" above). The haploid chromosome number of Olinia is 12, according to Takhtajan (1997), but c.f. Goldblatt (1976).
See Van Wyk (in Dahlgren & Van Wyk 1988), Schönenberger (2006: Rhynchocalyx), Schönenberger et al. (2006: Penaea), etc., and von Balthazar and Schönenberger (2006: Olinia) for general information; for anatomy, see Dickie and Gasson (1999: Penaea etc.), for embryology, see Tobe and Raven (1984b, c, 1985b) and Stephens (1909b).
Phylogeny. M. Sun et al. (2016) found that a clade [Olinia + Rhynchocalyx] was weakly supported as sister to the rest of the family. Maurin et al. (2021) noted that the position of Glischrocolla was not stable.