Plant a shrub or tree; true roots +, origin endogeneous, root cap +, apex multicellular; endodermis +; shoot apical meristem multicellular; lateral meristems +, cork cambium producing cork abaxially, vascular cambium producing phloem abaxially and xylem adaxially; lamina with mean venation density 1.8 mm/mm2 (to 5 mm/mm2).
EXTANT SEED PLANTS/SPERMATOPHYTA
Plant woody, evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins derived from (some) sinapyl and particularly coniferyl alcohols, thus containing p-hydroxyphenyl and guaiacyl lignin units, so no Maüle reaction; root xylem exarch, cork cambium deep seated; arbuscular mycorrhizae +; shoot apical meristem interface specific plasmodesmatal network; stem with vascular tissue around central pith [eustele], vascular bundles with interfascicular tissue, ectophloic, endodermis 0, xylem endarch; 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 +; stem cork cambium superficial; branches exogenous; leaves with single trace from vascular sympodium ["nodes 1:1"]; vascular bundles collateral [stem: phloem external; leaf: phloem abaxial]; stomata morphology?, pore opening controlled by abscisic acid; leaves with petiole and lamina, spiral, development basipetal, blade simple; axillary buds +, not associated with all leaves; prophylls two, lateral; plant heterosporous, sporangia borne on sporophylls; microsporophylls aggregated in indeterminate cones/strobili; true pollen +, grains mono[ana]sulcate, exine and intine homogeneous; ovules unitegmic, parietal tissue 2+ cells across, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development first endo- then exosporic, tube developing from distal end of grain, to ca 2 mm from receptive surface to egg, gametes two, developing after pollination, with cell walls, flagellae numerous; ovules increasing considerably in size between pollination and fertilization, female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large" [ca 8 mm3], but not much bigger than ovule, with morphological dormancy; embryo cellular ab initio, endoscopic, plane of first cleavage of zygote transverse, suspensor +, short-minute, embryo straight, shoot and root at opposite ends [allorrhizic], white, cotyledons 2; plastid transmission maternal; ycf2 gene in inverted repeat, two copies of LEAFY gene, PHY gene duplications [three - [BP [A/N + C/O]] - copies], nrDNA with 5.8S and 5S rDNA in separate clusters; mitochondrial nad1 intron 2 and coxIIi3 intron and trans-spliced introns present.
MAGNOLIOPHYTA
Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, [cyanogenesis in ANITA grade?], S [syringyl] lignin units common, positive Maüle reaction [syringyl:guaiacyl ratio more than 2-2.5:1], and hemicelluloses as xyloglucans; root apical meristem intermediate-open; root vascular tissue oligarch [di- to pentarch], lateral roots arise opposite or immediately to the side of [when diarch] xylem poles; origin of epidermis with no clear pattern [probably from inner layer of root cap], trichoblasts [differentiated root hair-forming cells] 0, exodermis +; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, associated gelatinous fibres [g-fibres] with innermost layer of secondary cell wall rich in cellulose and poor in lignin; starch grains simple; primary cell wall mostly with pectic polysaccharides, poor in mannans; tracheid:tracheid [end wall] plates with scalariform pitting, wood parenchyma +; sieve tubes enucleate, sieve plate with pores (0.1-)0.5-10< µm across, cytoplasm with P-proteins, cytoplasm not occluding pores of sieve plate, companion cell and sieve tube from same mother cell; sugar transport in phloem passive; nodes unilacunar [1:?]; stomata brachyparacytic [ends of subsidiary cells level with ends of pore], outer stomatal ledges producing vestibule; lamina formed from the
primordial leaf apex, margins toothed, development of venation acropetal, secondary veins pinnate, overall growth ± diffuse, venation hierarchical, fine venation reticulate, veins (1.7-)4.1(-5.7) mm/mm2, endings free; most/all leaves with axillary buds; flowers perfect, pedicellate, ± haplomorphic, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P not sharply differentiated, with a single trace, outer members not enclosing the rest of the bud, often smaller than inner members; A many, filament not sharply distinguished from anther, stout, broad, with a single trace, anther introrse, tetrasporangiate, sporangia in two groups of two [dithecal], ± embedded in the filament, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally, endothecium +, endothecial cells elongated at right angles to long axis of anther; tapetum glandular, cells binucleate; microspore mother cells in a block, microsporogenesis successive, walls developing by centripetal furrowing; pollen subspherical, tectum continuous or microperforate, ektexine columellar, endexine thin, compact, lamellate only in the apertural regions; nectary 0; G superior, free, several, ascidiate, with postgenital occlusion by secretion, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, carinal, dry [not secretory]; 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 [crassinucellate], nucellar cap?; megasporocyte single, hypodermal, megaspore tetrad linear, functional megaspore chalazal, lacking sporopollenin and cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; ovule not increasing in size between pollination and fertilization; pollen binucleate at dispersal, male gametophyte trinucleate, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing between cells, growth rate 20-20,000 µm/hour, outer wall pectic, inner wall callose, 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 gametes lacking cell walls, flagellae 0, double fertilization +, ovules aborting unless fertilized; P deciduous in fruit; seed exotestal, becoming much larger than ovule at time of fertilization; endosperm diploid, cellular [micropylar and chalazal domains develop differently, 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; embryogenesis cellular; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)n]; 2C genome size 1-8.2 pg [1 pg = 109 base pairs], whole genome duplication, 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, paleo AP3 and PI genes [paralogous B-class genes] +, with "DEAER" motif, SEP3/LOFSEP and three copies of the PHY gene, [PHYB [PHYA + PHYC]].
[NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS]
[MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]]: vessels +, elements with elongated scalariform perforation plates; 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]]]]: essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood 0; tectum reticulate; anther wall with outer secondary parietal cell layer dividing; carpels plicate; nucellar cap + [character lost where in eudicots?]; 12BP [4 amino acids] deletion in P1 gene.
[[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]] / MESANGIOSPERMAE: benzylisoquinoline alkaloids +; 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 [possible positiion]; embryo sac bipolar, 8 nucleate, antipodal cells persisting; endosperm triploid; ?germination.
[MONOCOTS [CERATOPHYLLALES + EUDICOTS]]: (veins in lamina often 7-17mm/mm2 or more [mean for eudicots 8.0]); (stamens opposite [two whorls of] P); (pollen tube growth fast).
[CERATOPHYLLALES + EUDICOTS]: ethereal oils 0.
EUDICOTS: myricetin, delphinidin scattered, asarone 0
[unknown in some groups, + in some asterids]; root epidermis derived from
root cap [?Buxaceae, etc.]; nodes 3:3; stomata anomocytic; flowers (dimerous), cyclic; K/outer P members with three traces, "C" with a single trace; A few, (polyandry widespread, initial primordia 5, 10, or ring, ± centrifugal), 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]; seed coat?
CORE EUDICOTS / GUNNERIDAE: (ellagic and gallic acids +); leaf margins serrate; compitum + [one place]; micropyle?; palaeohexaploidy [gamma triplication], PI-dB motif +, small deletion in the 18S ribosomal DNA common.
[ROSIDS ET AL. + ASTERIDS ET AL.] / PENTAPETALAE: root apical meristem closed; (cyanogenesis also via [iso]leucine, valine and phenylalanine pathways); flowers rather stereotyped:
5-merous, parts whorled; P = calyx + corolla, the calyx enclosing the flower in bud, sepals with three or more traces, petals with a single trace; stamens = 2x K/C, in two whorls developing internally/adaxially to the corolla whorl and successively alternating, (numerous, but then usually fasciculate and/or centrifugal); pollen
tricolporate; G [5], G [3] also common, when [G 2], carpels superposed, compitum +,
placentation axile, style +, stigma not decurrent;
endosperm nuclear; fruit dry, dehiscent, loculicidal [when a capsule]; RNase-based gametophytic incompatibility system present; floral nectaries with CRABSCLAW expression.
ASTERIDS / Sympetalae redux? / ASTERIDAE / ASTERANAE Takhtajan: nicotinic acid metabolised to its arabinosides; (iridoids
+); tension wood decidedly uncommon; C enclosing A and G in bud, (connate, if evident only early in development and then petals often appearing to be free); anthers dorsifixed?; (nectary gynoecial); style +, long; ovules unitegmic,
integument thick, endothelium +, nucellar epidermis does not persist; exotestal cells lignified, esp. on anticlinal and/or inner periclinal walls; endosperm cellular.
ellagic acid 0, non-hydrolysable tannins
not common; sugar transport in phloem active; inflorescence basically cymose; (numerous, usu. associated with increased numbers of C or G); (pollen with orbicules); style short[?]; duplication of the PI gene.
Evolution.Divergence & Distribution. Soltis et al. (2008: a variety of estimates) suggest that the asterid I and II clades separated 124-106(-85) m.y.a., Lemaire et al. (2011b) offer ages of (125-)114(-101) m.y. and N. Zhang et al. (2012), (96-)83(-68) m.y..
From fossil evidence Martínez-Millán (2010) suggested a much later date of around the Eocene only 55-33.9 m.y.a. for the diversification of most of the asterid I and II orders, but this estimate is about half the ages suggested by Beaulieu et al. (2013) and others.
Endress (2011a) suggested that stamens adnate to petals, haplostemony, and unitegmic ovules are key innovations somewhere around here. Indeed, this whole clade is notably speciose (Magallón & Sanderson 2001; Magallón & Castillo 2009), although it is more accurate to say that the six major clades, Boraginaceae s.l., Lamiales, Solanales, Asterales, Apiales and Dipsacales have high diversification rates, and within these clades it is usually a subclade that has these high rates... Of these clades, Magallón and Sanderson (2001) suggest that Asterales have the highest diversification rate (0.2717, 0.3295) while the honour goes to Lamiales in Magallón and Castillo (2009: 0.0928-0.1257). But note that within Asterales, Asteraceae are very speciose, and within Asteraceae, Asteroideae, and within just about all orders there are series of species-poor pectinations at the base of the ordinal trees, and these are often made up of woody plants (e.g. Lamiales, Apiales). So whatever may be driving diversification, it is likely to be combination of factors and acting at several places on the tree.
When looking at clade diversity within the whole tree, the situation becomes still more complicated. Garryales and Aquifoliales in particular are not very diverse and are sister to the rest of the asterid I and asterid II clades respectively. Members of these two small clades are woody, often trees of the rainforest, with rather small flowers and ovules that may be bitegmic; the fruits are usually fleshy - they are drupes for the most part - and a number have relatively large seeds, nearly always one per loculus. All in all, they are rather different from the mega-clades just mentioned, but in many respects they are more similar to Ericales, rosids, etc. Florally they may be somewhat different, but the stamens are by no means always adnate to the petals and some taxa have ovules with parietal tissue and/or are bitegmic, although very little is known about their ovules, embryology, etc.
Patterns of polyandry in the [asterid I + asterid II] clade differ from that in more basal clades (see below). There may also be a change in chemistry, ellagic acid being notably uncommon, although it is scattered through the rosid-Ericales parts of the tree. This is perhaps to be expected, there being a correlation between woodiness and tannin frequency and a negative correlation between tannin (generalized defence) frequency and alkaloid and other secondary metabolites (specific defence) frequencies (e.g. Feeney 1976; Silvertown & Dodd 1996: given the information in Levin 1976 the correlation of alkaloid presence with other features should be re-examined). Indeed, no family in the [asterid I + asterid II] clade has more than 50% tanniniferous species, only Rubiaceae and Caprifoliaceae, both with many woody members, being well represented (Mole 1993); the tannins involved are non-hydroysable tannins. Although sampling is skethcy, emission of isoprene gas shows a somewhat similar pattern, being known from Ericales, rosida (and also a few monocots and Magnoliales (see Kesselmeier & Staudt 1999; Sharkey et al. 2013). However, comparative phytochemical studies on Aquifoliales and the Garryales area are much needed.
Even with our current understanding of phylogeny and character distribution, it is likely that the asterid I and II clades have separate origins from a morphology very different to that of the florally flashy megadiverse clades they contain. If the unplaced families around Garryales (see below) turn out to form pectinations at the base of the asterid I clade, this evolutionary scenario would be clarified; simple parsimony might suggest that "corolla valvate, apex incurved; ovules 1-2/carpel, apical; fruit drupaceous" are fearures of the common ancestor of the whole [asterid I + asterid II] clade. Comprehensive phylogenetic studies in this area of the tree are badly needed.
Ecology & Physiology. Cornwell et al. (2008) found that litter decomposition of forbs that predominate in the asterid I and II clades was faster than that of graminoids, and although he did not compare deciduous trees and forbs, breakdown of litter was faster in deciduous trees than in evergreen trees; such differences are related to changes in the rate of nutrient cycling.
In both clades there are many annuals and herbaceous to shrubby perennials, and many of these have very small seeds of 10-2 grams or less (Linkies et al. 2010; Haig & Westoby 1991 for situations in which small seeds may be at an advantage).
The annual habit may be connected with differences in the details of the distribution of different mechanisms of phloem transport. Taxa with active phloem loading are particularly common here. Sugars or sugar alcohols, not in particularly high concentration in leaf tissues, are pumped into the phloem by the metabolic activities of the plant (Rennie & Turgeon 2009; Turgeon 2010b; Fu et al. 2011). This may be associated with herbivore deterrence, the sugars causing dessication of the tissues of the herbivore, and/or cellular debris quickly clogs the sieve pores, sealing the phloem, and/or the plant economizes on sugar production (Turgeon 2010b; Fu et al. 2011). Since woody taxa of the [asterid I + asterid II] clade have "herbaceous" mechanisms of sugar transport, the correlation may be phylogenetic and less immediately associated with plant habit. A somewhat different focus on/classification of transport types suggests that one active transport mechanism, the synthesis and transport of raffinose family oligosaccharides shows little correlation with plant habit but some correlation with climate, being relatively more common in plants from warmer parts of the world (Davison et al. 2011).
Albach et al. (2001a, see also Soltis et al. 2005b) assign possession of iridoids to the base of the asterid clade. However, this feature is placed higher up the tree, partly because of topological uncertainties, but partly because in Lamiales (for example), the four clades that are successively sister to other Lamiales either lack iridoids or have iridoids distinctively different (Oleaceae) from those in the other members of the clade; whether or not Carlemanniaceae have iridoids is unknown.
Pollination Biology & Seed Dispersal. The asterid I clade in particular includes many large- and monosymmetric-flowered taxa that have dry fruits with many seeds (but c.f. Convolvulaceae, Lamiaceae, Verbenaceae - four seeds/fruit at a maximum); the apices of the petals tend to be rounded (but c.f. Acanthaceae). The asterid II clade has proportionally more taxa with small flowers that are aggregated into conspicuous inflorescences that appear polysymmetric to the pollinator; the dry fruits have few seeds (but c.f. Campanulaceae, Goodeniaceae, etc.); the apices of the petals tend to be pointed. In general, members of the [asterid I + asterid II] clade have rather small seeds (Linkies et al. 2010).
There are relatively few cases of polyandry in the [asterid I + asterid II] clade, and these are often associated with anisomery. There can be considerable increases in the numbers of perianth parts and/or carpels, the latter occurring in a single whorl. Examples are some species of Schefflera (e.g. Plerandra s. str.: Araliales-Araliaceae), Anthocleista and Potalia (Gentianales-Gentianaceae-Potalieae) and some Gentianaceae-Chironieae (flowers to 16-merous), Lamiaceae-Symphorematoideae (Lamiales), as well as Codon, Hoplestigma, and Lennoa and relatives (all Boraginaceae s.l., but not immediately related to each other). In Plerandra, at least, a kind of fasciation of the flower seems to have occurred, and there are about as many stamens as carpels (Sokoloff et al. 2007b). Dialypetalanthus and Theligonum (both Rubiaceae) also have more numerous stamens that would be expected, but how the flowers are constructed here is unclear. Paracryphiaceae (Paracryphiales) also show interesting variation in floral merism. Polyandry is much more commomn in other eudicots and it usually occurs independently of any changes in sepal, petal or carpel number - there are of course exceptions, such as Crassulaceae, where the stamens are equal in number to the carpels, Actinidia, where there are many carpels in a single whorl and many stamens, and Conostegia (Melastomataceae), where stamen and carpel number may be similar (see Wanntorp et al. 2011 for this and some other examples). The near absence of other kinds of increase in stamen number may reflect a change in underlying floral organisation/development in the stem [asterid I + asterid II] clade, perhaps in turn connected with the rather stereotyped (in terms of basic floral construction) flowers so common here.
Chemistry, Morphology, etc. For a possible duplication of the PI gene here - or in the asterid I clade - see Viaene et al. (2009), but more detailed sampling is required to fully understand the pattern of duplication and loss of this gene in asterids.
Phylogeny. Aquifoliaceae were included in the asterid II clade by
Gustafsson et al. (1996) and B. Bremer (1996). However, Qiu et al. (2011) found weak support for a set of relationships [[paraphyletic Icacinaceae plus Garryales [Aquifoliaceae + rest of asterid I clade]] [rest of asterid II clade]] - for more on relationships of Icacinaceae, see below. Similarly, the I copy of the duplicated RPB2 gene is retained in most of the asterid I clade as well as Aquifoliaceae (and all? Aquifoliales), and there is a comparable pattern in the loss of introns 18-23 in the d copy; both point to the possibility that Aquifoliales might belong in the asterid I clade (Oxelman et al. 2004b). Since both Garrya and Eucommia have only the d copy, perhaps this is a feature of Garryales in particular, or part of them. Sampling needs to be improved, but optimisation of the persistence/loss of the I copy on the asterid tree will probably be difficult (Oxelman et al. 2004b). Aquifoliaceae also seem to lack the PI duplication of other members of the [asterid I + asterid II] clade (Viaene et al. 2009: no other Aquifoliales examined). N. Zhang et al. (2012) found weak support in an analysis of nuclear genes for an [Aquifoliales + Garryales] clade. Clearly there are some loose ends that need to be tidied up.
G [2], superposed; loss of introns 18-23 in d copy of RPB2 gene.
Evolution.Divergence & Distribution. Magallón and Castillo (2009) estimated an age of ca 96.85 m.y. for this crown group, while Moore et al. (2010: 95% HPD) ages of (80-)76(-71) m.y.. See Martinez-Millán (2010) for fossil-based estimates for the age of this clade.
Phylogeny. Although Garryales are often found sister to the rest of the asterid Is, the composition of the order is unclear. Oncothecaceae have been considered close, but neither they nor the other families or genera mentioned immediately below link strongly to Garryales (e.g. Kårehed 2001, 2002b; for the position of Oncothecaceae, see Cameron 2001, 2003; Olmstead et al. 2000; B. Bremer et al. 2002). Pyrenacantha, Chlamydocarya,
Sarcostigma, Iodes, and Icacina (Icacinaceae s. str.) form
a clade in the rbcL tree of Savolainen et al. (2000b), although there
placed (but with very little support) at the base of the rosids; these genera
belong to Icacinaceae group III of Bailey and Howard (1941) and are included below in Icacinaceae s. str. There was initially only weak support for
Icacinaceae in this position (D. Soltis et al. 2000), but Kårehed (2001)
identified four ex-Icacinaceous
groups associated with Garryales: Icacinaceae s. s.tr, and the Cassinopsis, Emmotum and Apodytes groups. However, groupings within a more widely circumscribed
Garryales could not be identified, nor did the larger Garryales have any strong
support. Relationships in the four genera of this part of Icacinaceae included in the analysis of B. Bremer et al. (2002) are also consistent with the classification adopted here. The Bayesian analysis of Soltis et al. (2007) recovered Icacina as sister to all other asterid I taxa included (0.99 pp), while Soltis et al. (2011) found very weak support for an association of Icacina with Garryales, but Oncotheca was not a member of this clade, although support for its position (the whole lot formed a paraphyletic assemblage at the base of the asterid I clade) was very weak.
Studies on the duplication of the RPB2 gene show that the I copy persists in most of the asterid I clade almost alone in the whole rosid/asterid group (see also discussion under Trochodendrales and [Dilleniales]), as well as in Ericales. In a parsimony analysis of combined molecular and morphological data Lens et al. (2008a) found [Oncothecaceae + unassigned ex-Icacinaceae] (72% bootstrap) to be sister to the asterid I clade, but with little support, while in a Bayesian analysis the first clade was joined by Garryales (but little support for the enlarged clade) as sister to other asterid I groups (1.0 p.p.).
For literature on Icacinaceae in the old sense, which may refer to any and all of these groups, see Bailey and Howard (1941: anatomy), Mauritzon (1936c) and Fagerlind
(1945a), both embryology, Heintzelmann and Howard (1948: crystals and indumentum), Padmanabhan (1961: embryology), Sleumer (1971a: general), van Staveren and Baas
(1973: epidermis), Baas (1973: epidermis, 1974: stomata), Lobreau-Callen (1977, 1980: pollen), Kaplan et al. (1991: chemistry), and Teo and Haron (1999: anatomy). Lens et al. (2008a) provide a detailed anatomical survey in a phylogenetic context.
Classification. This clade is called the lamiids by B. Bremer et al. (2002).
Unplaced: corolla valvate, apex incurved; ovules 1-2/carpel, apical; fruit drupaceous.
Morphologically, it would be easy to include this group in an expanded Garryales if the phylogeny suggests this, if paraphyletic at the base of the asterid I clade, characters of Garryales, the asterid I and possibly also for the [asterid I + asterid II] clade will all have to be reworked.
Chemistry, Morphology, etc. The stomata, perhaps modified
paracytic, are distinctive. Carpenter and Dickison (1976)
described the stamens as being opposite the petals, but drew them as being
opposite the sepals. Oncotheca
macrocarpa, fairly recently described (McPherson et al. 1981, = O. humboldtiana), has stamens quite
unlike those of O. balansae; the incurved, pointed connective of stamens
of the latter species is responsible for the generic name. Oncothecaceae are embryologically
unknown.
Some information is taken from Baas
(1975: anatomy), Lobreau-Callen (1977: pollen), and Carpenter (1975: general).
Previous relationships. The family was included in Theales
by Cronquist (1981) and Takhtajan (1997).
1/7. Costa Rica, Panama and N.W.
South America (map: from Lozano C. & Lozano 1988). [Photo - Flower]
Metteniusaceae are rather undistinguished vegetatively,
but the combination of exstipulate, entire leaves and pentalacunar nodes is odd. The flowers are distinctive: the petals are spreading and hairy adaxially and each long, locellate (and sometimes bright orange) anther theca becomes broadly recurved in a semicircle. The locelli are in four rows, and each loecllus opens separately.
Chemistry, Morphology, etc. For general information, see Lozano C. and Lozano (1988); for anatomy, etc., see Reed (1955), and for floral development, see González and Rudall (2010). It is unclear if the two ovules are from adjacent carpels (their Fig. 10) or from the same carpel (Fig. 6k, l]); since the gynoecium is paracarpous, the placentation is parietal.
Phylogeny. In morphological phylogenetic analyses Metteniusa fits quite comfortably into Cardiopteridaceae, ex Icacinaceae (Kårehed 2001: Cornaceae not included). However, molecular analyses suggest a position in the asterid I area, and petiole anatomy, carpel number, etc., are similar to Oncothecaceae in particular (González & Rudall 2007, esp. 2010; González et al. 2007); I have summarized characters assuming this relationship.
Previous Relationships. The flowers of Metteniusa suggest Cornales s. str., but its ovary is superior. A monotypic Metteniusales were placed immediately after a highly heterogeneous Icacinales by Takhtajan (1997); Metteniusa was not mentioned by Cronquist (1981).
Trees, or lianes clmbing by
non-axillary branch tendrils or twining; (plants Al-accumulators); monoterpene indole alkaloid camptothecin +, iridoids ?; secondary thickening often atypical [included phloem +, etc.];
vessel elements with simple perforation plates; banded and/or vasicentric axial parenchyma; (crystal sand in wood rays); phloem stratified; nodes 1:1;
(medullary bundles + - Iodes), petiole bundles arcuate and wing or
annular (and medullary); stomata cyclocytic (anomocytic), hairs unicellular,
often adpressed and ± T-shaped, also globular; leaves spiral (opposite),
conduplicate(-plicate), lamina margins entire, (toothed), (palmately lobed; secondary veins palmate); plant dioecious[?],
inflorescence branched, spicate or racemose, pedicels articulated; (flowers 4-merous); K
connate (0 – Pyrenacantha; ± free - Phytocrene), (C
free),(adaxially keeled), apices of corolla lobes inflexed; nectary 0 (+): staminate flowers: A
dorsifixed, (epipetalous); pollen also porate, echinate; pistillode +;
carpellate flowers: staminodes +/0; G also 1?, style + and stigma punctate, or style 0 and stigma broad; ovules (apically bitegmic - Phytocrene), tenuinucellate/thinly crassinucellate, integument vascularized (not), funicular obturator +;
fruit a 1-seeded drupe, flattened and/or ribbed or pocked or not, (locule walls papillate internally), K persistent; seed coat?, no testa bundles;
endosperm copious to 0, ruminate or not, chalazal haustorium + [Nothapodytes],
starchy [only Merrilliodendron?], embryo usu. long, cotyledons
foliaceous; n = 10, 12.
24(?25)[list of genera in Icacinaceae in the old sense]/149(150): Pyrenacantha (30), Iodes (28). Pantropical, inc. W. Pacific, to China and Japan (map: Sleumer 1971a; Utteridge & Brummitt 2007; Trop. Afr. Fl. Pl. Ecol. Distr. 5. 2010).
Icacinaceae s. str. are undistinguished vegetatively,
having exstipulate and usually entire leaves; a number are vines and these may
have opposite leaves and branch tendrils that are not strictly axillary. The flowers are small, with a connate corolla and an at most rather
short and slender style. Their single-seeded, drupaceous fruits are
longer than broad and often flattened and the stones are variously ribbed or pocked.
Evolution.Divergence & Distribution. Magallón and Castillo (2009) offer estimates of ca 96.85 m.y. for stem group Icacinaceae - and Oncothecaceae and Mettiusaceae. Lemaire et al. (2011b) date the divergence of Icacina from the rest of the asterid I clade (including Garryales) at ca 102 m.y., while Wikström et al. (2001) estimated the age of crown Icacinaceae at (75-)70(-65) m.y.a. [check].
Icacinaceae were widespread and diverse in the Northern Hemisphere during the Eocene, with genera now restricted to Southeast Asia-Malesia being found in North America (Rankin et al. 2008; Stull et al. 2011 and references); for fossils of Iodeeae, see Pigg et al. (2008a). Endocarps identifiable as the Old World Phytocreneae are known from both North and South America in Palaeocene deposits about 60-58 m.y.o. (Stull et al. 2012).
Ecology & Physiology. For the indole alkaloid camptothecin, found in a number of genera, see Lorence and Nessler (2004). Camptothecin may be derived from secologanin, and ultimately it may be synthesized by an endophytic fungus related to something like Rhizopus oryzae or the glomeromcyete Entrophosphora (Puri et al. 2005; Wink 2008; Shweta et al. 2010). The enzyme that camptothecin targets occurs in Icacinaceae, too, but there it is probably protected by a change in its amino acid sequence (Sirikantaramas et al. 2009).
Chemistry, Morphology, etc. The description above
largely refers to the Icacina group (see Kårehed 2001). Hoseia, with its long-petiolate
leaves that have palmate venation and long-dentate margins, is particularly distinctive
vegetatively. The family is very poorly known embryologically.
For additional information, see Utteridge et al. (2005: general), also Rankin et al. (2008), Pigg et al. (2008a), and Stull et al. (2011, 2012), all fruit anatomy, especially of fossils, and Cremers (1973, 1974) for some growth patterns.
Phylogeny.
Classification. Phytocreneae (Chlamydocarya, Miquelia, Phytocrene, Polycephalium, and Pyrenacantha) have fruits with somewhat flattened and pock-marked stones, the outer cells of the sclereidal layer with sinuous, interdigitating walls, and the invaginations of the stone often signal ingainations into the the endosperm (Stull et al. 2012 and references).
Previous Relationships. Other
genera that used to be included in Icacinaceae are placed in the asterid II group, i.e. in Aquifoliales (as Cardiopteridaceae and Stemonuraceae) and Apiales (as Pennantiaceae: Kårehed 2001, 2002b, 2003).
Synonymy: Iodaceae van Tieghem, Phytocrenaceae R. Brown, Pleurisanthaceae van Tieghem, Sarcostigmataceae van Tieghem - Icacinales van Tieghem - Icacinanae Doweld
Apodytes - 3/10: Tropics, to Australia (Queensland) (map: from Sleumer 1971a)- vessel elements with simple [Rhaphiostylis] or scalariform perforation
plates; bordered pits +; xylem parenchyma various; nodes 1:1, 3:3; stomata anomocytic
(cyclocytic); leaves spiral or two-ranked; fruit very asymmetric, ribbed, style
thin, persistent; n = 20, ?22. Probably to include Dendrobangia - M. Schori, pers. comm. vi.2010. For fruit morphology, see Potgeiter et al. (1994b).
Cassinopsis - 1/4: Africa
and Madagascar – vessel elements with scalariform perforation plates; nodes
3:3; stomata cyclocytic; hairs not ± T-shaped; leaves opposite. For fruit morphology, see Potgeiter et al. (1994a).
Emmotum (Emmotaceae van Tieghem) - 4(?6)/21(32):
Central and South America, West Indies, rarely Malesia (map: from Sleumer 1971a) – vessel
elements with scalariform perforation plates; bordered pits +; diffuse apotracheal
parenchyma +; nodes 3:3; (hairs T-shaped; stellate); stomata cyclocytic(-anomocytic), (Platea; leaves ± conduplicate in bud); flowers 4-5-merous, (imperfect); C (0), ridged adaxially or not, with adaxial hairs (none); G [3], one carpel fertile, (2-3-septate: Emmotum), style very short to medium; ovules 2/fertile carpel, collateral or superposed; fruit flattened and symmetric; (stone ± ribbed); embryo short to long; n = ? Perhaps includes Calatola – scalariform perforation
plates; nodes 3:3; leaves toothed, conduplicate, Cordia growth pattern. Some information is taken from Howard (1941), Sleumer (1971a) and de Stefano and Fernández-Concha (2011),
Synonymy: Emmotales Doweld
For other
information, see Bailey and Howard (1941, their group II: anatomy), Fagerlind
(1945: embryology), Heintzelmann and Howard (1948), Padmanabhan (1961: embryology), Sleumer (1971a: general), van Staveren and Baas
(1973: epidermis), Baas (1973: epidermis, 1974: stomata), Lobreau-Callen (1980: pollen), Kaplan et al. (1991: chemistry), and Teo and Haron (1999: anatomy). Kårehed
(2001, 2002c) discusses the taxa in their current circumscriptions. The wood occasionally fluoresces.
Woody; route II decarboxylated
iridoids [inc. aucubin], gutta +; fibres with bordered pits; petiole bundles arcuate; sclereids +; stomata?; hairs unicellular; plants dioecious; flowers
small; C valvate, free; anthers basifixed; pollen ± atectate; ovary 1-celled, styles branched to the base, spreading, stigmatic much of their length; ovules 1-2/carpel, apical,
apotropous, parietal tissue 3< cells across, endothelium 0; fertilization delayed; fruit indehiscent. - 2 families, 3 genera, 18 species.
Note: Possible apomorphies are now being added throughout the site; they are in bold. However, the actual level at which many of these features, particularly the more cryptic ones, should be assigned
is unclear. This is because there is very considerable homoplasy for many characters, with with variation within and between clades. Furthermore, basic information for all too many characters is very incomplete, often coming from taxa well embedded in the clade of interest and so making the position of any putative apomorphy uncertain. Then there is the not-so-trivial issue of how ancestral states are reconstructed...
Evolution.Divergence & Distribution. Janssens et al. (2009) date stem group Garryales to 112±9.3 m.y.a. and the crown group to 20±8.6 m.y.; Bremer et al. (2004) suggested a stem group age of ca 114 m.y.; Lemaire et al. (2011b) a stem group age of (118-)98(-87) and a crown group age of (91-)63(-31) m.y. Magallón and Castillo (2009) offer estimates of ca 96.8 and 49.8 m.y. for stem and crown group ages respectively.
Pollination Biology & Seed Dispersal. In all three genera there is a lengthy period (11 days to four weeks) between pollination and fertilization (Sogo & Tobe 2006); it would be interesting to examine Icacinaceae and related genera, Metteniusaceae and Oncothecaceae from this point of view.
Chemistry, Morphology, etc. Although the iridoid aucubin is found in both families, it is not unique to them; neither family can synthesize catalpol (Grayer et al. 1999). Much work is needed on basic
embryology, etc. The nucellus on the sides of the embryo sac is not very thick, even if the ovules have parietal tissue 3-8 cells across.
Phylogeny. The order is narrowly circumscribed (see above).
Evergreen shrubs or
trees; tannins 0, petroselenic and chlorogenic acids +; vessel elements with
scalariform perforation plates; rays at least 10 cells wide, with square or upright
cells; nodes 3:3; also crystal sand +; cuticle waxes as tubules (and platelets);
stomata paracytic; hairs with
counter-clockwise ridges; leaves opposite, ± connate basally, lamina vernation conduplicate;
inflorescence terminal; flowers 4-merous; staminate flowers: A not
epipetalous, pistillode; carpellate flowers: staminodes 0; G inferior, [(3)]; ovule 1/carpel, large placental obturator +; I]]: fruit a berry; testa thick, outer
part sarcotestal, inner part with cells elongated tangentially; endosperm
nuclear, with hemicellulose, embryo short.
2[list]/17 - two genera below. W. North
America, Central America, the Greater Antilles and East Asia.[Photo - Fruit]
1. Garrya Lindley
Diterpenoid alkaloids
+; fibres with helical thickening; lamina margins ± entire, cartilaginous; inflorescences
catkinate, bracts ± connate; staminate flowers: P [?= C]
valvate, connate apically; A alternating with P; (pollen colporate, partly
tectate); nectary 0; pistillode +; carpellate flowers: P [?= K] 2, minute, or 0; ovule epitropous, integument 12-30 cells across, endothelium 0, parietal tissue 4-5 cells thick, (nucellar cap 2 cells across), hypostase +, funicle quite long, with "collar" below the ovule; antipodals persistent or not; testa
multiplicative, exotestal cells large, palisade, fleshy, most of testa not persistent; suspensor very long, endosperm ?green, starchy; n = 11.
1/13. W. North
America, Central America and the Greater Antilles (map: from Dahling 1978).
2. Aucuba Thunberg
Gutta percha ?, flavonols, kaempferol
+; vascular tracheids present; pericyclic fibres 0; lamina margins serrate; K
minute or 0, C with early tube formation; staminate flowers: pollen?; carpellate flowers: G 1, stylulus +,
stigma capitate to shortly decurrent, bilobed; nectary on top of G; integument "thick", parietal tissue ca 8 cells across, (nucellar cap 2 cells across), endothelium?; (megaspore mother cells several); ?seed coat; n = 8.
1/4. Sikkim to N. Burma, China and Taiwan to Japan (see map above).
Synonymy: Aucubaceae Berchtold & J. Presl
Garryaceae are evergreen, woody plants that can be
recognised by their exstipulate, opposite leaves that are basally connate,
flowers with an inferior ovary and only one whorl of the perianth well
developed, and baccate fruits.
Evolution.Divergence & Distribution. Fossil leaves of Aucuba are reported from the Eocene of Washington (Wehr & Hopkins 1994).
Chemistry, Biology, etc. For discussion of the flowers of Garrya,
in which both calyx and corolla may be absent when mature, see Baillon (1877), Hallock
(1930) and Eyde (1964); Baillon provides perhaps the only report of minute
"sepals" being visible in the very young carpellate flower. The calyx is reported to be
much reduced in staminate flowers, but the corolla is more reduced than the
calyx in carpellate flowers; in the latter, the bracteoles may be adnate to the
ovary and appear to represent the calyx. Liston (2003) thought that the staminate flowers had a vestigial disc, rather than a superior ovary, as had been suggested. More work on floral development is needed.
There seems to be quite a bit of disagreement over embryological details of Garrya, thus Eyde (1964) described the ovules as being tenuinucellate, while Hallock (1930) and Kapil and Mohana Rao 1967) described and illustrated them
as having a very thick parietal layer. For some details of the ovule of Aucuba, see Palm and Rutgers (1917); they noted (p. 121) that the parietal tissue kept on dividing, forming a "mighty cap on the embryosac". There are sometimes two ovules - does this imply that there are two carpels (Horne 1914)?
For chemical information, see Iwashina et al. (1997), for inflorescence morphology, esp. of Garrya, see Jahnke (1986), floral development, see Reidt and Leins (1994), and for general
floral information, see Horne (1914). For wood anatomy of Garrya, see Moseley and Beeks (1955), and for that of both genera, see Noshiro and
Baas (1998). For additional general information, see Liston (2009).
Classification. The apparent dissimilarity of Garrya
and Aucuba masks extensive similarities, and the two can be intergrafted
quite readily (Horne 1914). The two families are combined (see A.P.G. 2009).
For a monograph of Garrya, see Dahling (1978).
Previous Relationships. The relationships of Garrya in particular have been a bit of an enigma: Moseley and Beeks (1955) compared its wood anatomy with that of taxa that are here placed in 12 separate orders, mostly rosids. Aucuba was placed in Cornaceae by Cronquist (1981), Garryaceae were separate, but near by, while Takhtajan (1997) placed Garryaceae and Aucubaceae in separate, but adjacent, orders.
Deciduous trees;
O-methylated flavonols, little oxalate accumulation, inulin +, tanniniferous; hairs micropapillate; laticifers
+, articulated; vessel elements with simple
perforations; true tracheids and rays alone, tracheid/tracheid pits circular, bordered; phloem fibres +; nodes 1:1; cuticle wax crystalloids 0; stomata
anomocytic; buds perulate; leaves spiral, lamina vernation, supervolute-curved, margins toothed;
flowers axillary, bracteoles 0; P 0; staminate flowers: A 5-12, filaments short, connective prolonged, endothecium biseriate; tapetal cells 2-6-nucleate; carpellate flowers: one carpel aborts; ovules 2/carpel, integument 5-9 cells across, micropyle long [700-1000 µm long], parietal tissue 3-5 cells across, nucellar cap ca 3 cells across; archesporium multicellular;
fruit a samara; seed 1, testa thin; endosperm copious, embryo long; n = 17; chloroplast ORF184 lost.
1[list]/1: Eucommia ulmoides. Central China (map: from Guo 2000; Wang et al. 2003; green crosses are fossil distribution, approximate only, mostly from Ferguson et al. 1997).
The family can be recognised vegetatively by its
strongly serrate, spirally arranged, exstipulate leaves; when the lamina is
pulled apart, the two halves are held together by threads of gutta. The flowers, with their two, spreading,
decurrent stigmas and the samara fruits, are rather like those of an elm (Ulmaceae), but there is
no perianth.
Evolution.Divergence & Distribution. Wikström et al. (2001) estimated the age of stem Eucommia at 59-55 m.y. Eucommia fossils occur widely in the North Temperate region from the Palaeocene onwards, being found as far south as central Mexico (Call & Dilcher 1997; Y.-F. Wang et al. 2003; Manchester et al. 2009).
Pollination Biology & Seed Dispersal. Whether chalazogamy occurs in Eucommia is unclear. Sogo and Tobe (2006c) noted that some pollen tubes might grow towards the chalaza and more than one tube may proceed down the lengthy micropyle, but Eckardt (1963) did record chalazogamy; the pollen tube is also sometimes branched).
Chemistry, Morphology, etc. The teeth have glandular apices,
and associated veins approach them (Hickey & Wolfe 1975). Cullen (1978) described the leaf vernation as being
involute. The lateral nucellar tissue is thin, ca 2 cells across, and the tissue above the embryo sac is relatively much more prominent (Eckardt 1963). For embryology, etc., see Zhang et al. (1990).
Previous Relationships.Eucommia has often been associated with Euptelea (see Ranunculales), as in Cronquist (1981), but the chemistry and ovule of the former are consistent with a position in the asterids.
parenchyma +; nodes 3:3; (hairs T-shaped; stellate); stomata cyclocytic(-anomocytic), (Platea; leaves ± conduplicate in bud); flowers 4-5-merous, (imperfect); C (0), ridged adaxially or not, with adaxial hairs (none); G [3], one carpel fertile, (2-3-septate: Emmotum), style very short to medium; ovules 2/fertile carpel, collateral or superposed; fruit flattened and symmetric; (stone ± ribbed); embryo short to long; n = ? Perhaps includes Calatola – scalariform perforation
plates; nodes 3:3; leaves toothed, conduplicate, Cordia growth pattern. Some information is taken from Howard (1941), Sleumer (1971a) and de Stefano and Fernández-Concha (2011), 
![[Photo - Flower]](javascript:showImage('http://mobot.mobot.org/cgi-bin/search_vast?w3till=MOA-04674_001.jpg',600,500)){kind=link}
![[Photo - Fruit]](javascript:showImage('http://mobot.mobot.org/cgi-bin/search_vast?w3till=MOA-04493_001.jpg',600,500)){kind=link}