EMBRYOPSIDA Pirani & Prado

Gametophyte dominant, independent, multicellular, thalloid, with single-celled apical meristem, showing gravitropism; rhizoids +, unicellular; flavonoids + [absorbtion of UV radiation]; chloroplasts lacking pyrenoids; protoplasm dessication tolerant [plant poikilohydric]; cuticle +; cell walls with (1->4)-ß-D-glucans [xyloglucans], lignin +; several chloroplasts per cell; glycolate metabolism in leaf peroxisomes [glyoxysomes]; centrioles in vegetative cells 0, metaphase spindle anastral, predictive preprophase band of microtubules, phragmoplast + [cell wall deposition spreading from around the spindle fibres], plasmodesmata +; antheridia and archegonia jacketed, stalked; spermatogenous cells monoplastidic, centrioles develop de novo, associated with basal bodies of flagellae, multilayered structure +, proximal end of basal bodies lacking symmetry, stellate pattern associated with doublet tubules of transition zone; spermatozoids with a left-handed coil; male gametes with 2 lateral flagellae; oogamy; diploid embryo initially surrounded by haploid gametophytic tissue, plane of first division horizontal [with respect to long axis of archegonium/embryo sac], suspensor/foot +, cell walls with nacreous thickenings; sporophyte multicellular, with at least transient apical cell [?level], sporangium +, single, dehiscence longitudinal; meiosis sporic, monoplastidic, microtubule organizing centre associated with plastid, cytokinesis simultaneous, preceding nuclear division, sporocytes 4-lobed, with a quadripolar microtubule system; spores in tetrads, sporopollenin in the spore wall, wall with several trilamellar layers [white-line centred layers, i.e. walls multilamellate]; close association between the trnLUAA and trnFGAA genes on the chloroplast genome.

Many of the bolded characters in the characterization above are apomorphies of subsets 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 common ancestor of the group.

STOMATOPHYTES

Abscisic acid, ?D-methionine +; sporangium with seta, seta developing from basal meristem [between epibasal and hypobasal cells], sporangial columella + [developing from endothecial cells]; stomata +, anomocytic, cell lineage that produces them with symmetric divisions [perigenous]; underlying similarities in the development of conducting tissue and in rhizoids/root hairs; spores trilete; polar transport of auxins and class 1 KNOX genes expressed in the sporangium alone; MIKC, MI*K*C* and class 1 and 2 KNOX genes, post-transcriptional editing of chloroplast genes; gain of three group II mitochondrial introns.

[Anthocerophyta + Polysporangiophyta]: archegonia embedded/sunken in the gametophyte; sporophyte long-lived, chlorophyllous, nutritionally largely independent of the gametophyte; sporophyte-gametophyte junction interdigitate, sporophyte cells showing rhizoid-like behaviour.

POLYSPORANGIOPHYTA†

Sporophyte well developed, branched, free living, sporangia several; spore walls not multilamellate [?here]; apical meristem +.

EXTANT TRACHEOPHYTA / VASCULAR PLANTS

Photosynthetic red light response; water content of protoplasm relatively stable [plant homoiohydric]; control of leaf hydration passive; (condensed or nonhydrolyzable tannins/proanthocyanidins +); sporophyte with basipetal polar auxin transport; vascular tissue +, sieve cells + [nucleus degenerating], tracheids +, in both protoxylem and metaxylem; endodermis +; root xylem exarch [development centripetal]; stem with an apical cell; branching dichotomous; leaves spirally arranged, blades with mean venation density 1.8 mm/mm2 [to 5 mm/mm2]; sporangia adaxial on the sporophyll, derived from periclinal divisions of several epidermal cells, wall multilayered [eusporangium]; columella 0; tapetum glandular; gametophytes exosporic, green, photosynthetic; stellate pattern split between doublet and triplet regions of transition zone; placenta with single layer of transfer cells in both sporophytic and gametophytic generations, embryonic axis not straight [root lateral with respect to the longitudinal axis; plant homorhizic].

[MONILOPHYTA + LIGNOPHYTA]

Branching ± monopodial; lateral roots +, endogenous, root apex multicellular, root cap +; tracheids with scalariform-bordered pits; leaves with apical/marginal growth, venation development basipetal, growth determinate; sporangia borne in pairs and grouped in terminal trusses, dehiscence longitudinal, a single slit; cells polyplastidic, microtubule organizing centres not associated with plastids, diffuse, perinuclear; male gametes multiflagellate, basal bodies staggered, blepharoplasts paired; chloroplast long single copy ca 30kb inversion [from psbM to ycf2].

LIGNOPHYTA†

Plant woody; lateral root origin from the pericycle; branching lateral, meristems axillary; cork cambium + [producing cork abaxially], vascular cambium bifacial [producing phloem abaxially and xylem adaxially].

EXTANT SEED PLANTS / SPERMATOPHYTA

Plant 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 [hence with p-hydroxyphenyl and guaiacyl lignin units, so no Maüle reaction]; root stele with xylem and phloem originating on alternate radii, not medullated [no pith], cork cambium deep seated; arbuscular mycorrhizae +; shoot apical meristem interface specific plasmodesmatal network; stem with vascular cylinder around central pith [eustele], phloem abaxial [ectophloic], endodermis 0, xylem endarch [development centrifugal]; 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]; stomatal pore with active opening in response to leaf hydration, control by abscisic acid, metabolic regulation of water use efficiency, etc.; leaves with petiole and lamina, 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 linear, functional megaspore single, chalazal, lacking sporopollenin, megasporangium indehiscent; pollen grains landing on ovule; male gametophyte development initially endosporic, lacking chlorophyll, tube developing from distal end of grain, gametes two, developing after pollination, with cell walls; 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, embryonic axis straight [shoot and root at opposite ends; plant allorhizic], white, cotyledons 2; plastid transmission maternal; ycf2 gene in inverted repeat, whole nuclear genome duplication [zeta duplication], 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.

ANGIOSPERMAE / MAGNOLIOPHYTA

Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, 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 1:?; stomata brachyparacytic [ends of subsidiary cells level with ends of pore], outer stomatal ledges producing vestibule, reduction in stomatal conductance to increasing CO2 concentration; lamina formed from the primordial leaf apex, margins toothed, development of venation acropetal, overall growth ± diffuse, venation hierarchical-reticulate, secondary veins pinnate, 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 +, members 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], ± 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 columellate, endexine +, thin, compact, lamellate only in the apertural regions; nectary 0; carpels present, 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, functional megaspore, chalazal, lacking cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; supra-stylar extra-gynoecial compitum +; ovule not increasing in size between pollination and fertilization; pollen grains landing on stigma, bicellular at dispersal, mature male gametophyte tricellular, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing between cells, growth rate (20-)80-20,000 µm/hour, 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 gametes lacking cell walls, flagellae 0, double fertilization +, ovules aborting unless fertilized; P deciduous in fruit; seed exotestal, much larger than ovule at time of fertilization; endosperm diploid, cellular, heteropolar [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; dark reversal Pfr → Pr; Arabidopsis-type telomeres [(TTTAGGG)n]; 2C genome size 1-8.2 pg [1 pg = 109 base pairs], whole nuclear genome duplication [epsilon duplication]; protoplasm dessication tolerant [plant poikilohydric]; 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]]]]]: 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]]]]: vessel elements with scalariform perforation plates in primary xylem; essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood +; 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 +; 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 [possible position]; pollen tube growth intra-gynoecial; embryo sac bipolar, 8 nucleate, antipodal cells persisting; endosperm triploid.

[MONOCOTS [CERATOPHYLLALES + EUDICOTS]]: (extra-floral nectaries +); (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.

EUDICOTS: (Myricetin, delphinidin +), 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; 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?

[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]: ?

CORE EUDICOTS / GUNNERIDAE: (ellagic and gallic acids +); leaf margins serrate; compitum + [one place]; micropyle?; whole nuclear genome duplication [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, internal/adaxial to the corolla whorl, 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.

[DILLENIALES [SAXIFRAGALES [VITALES + ROSIDS s. str.]]]: stipules + [usually apparently inserted on the stem].

[SAXIFRAGALES [VITALES + ROSIDS]] / ROSANAE Takhtajan / SUPERROSIDAE: ??

[VITALES + ROSIDS] / ROSIDAE: anthers articulated [± dorsifixed, transition to filament narrow, connective thin].

[VITALES + ROSIDS]: ?

ROSIDS: (mucilage cells with thickened inner periclinal walls and distinct cytoplasm); embryo long; genome duplication; chloroplast infA gene defunct, mitochondrial coxII.i3 intron 0.

ROSID I / FABIDAE / [ZYGOPHYLLALES [the COM clade + the nitrogen-fixing clade]]: endosperm scanty.

[the COM clade + the nitrogen-fixing clade]: ?

[FABALES [ROSALES [CUCURBITALES + FAGALES]]] / the nitrogen-fixing clade: (N-fixing by associated root-dwelling bacteria); tension wood +; seed exotestal.

[ROSALES [CUCURBITALES + FAGALES]]: ovules 1-2/carpel, apical.

[CUCURBITALES + FAGALES]: P parts similar; ovary inferior; fruit 1-seeded, indehiscent.

Age. The age for this node has been estimated at (107-)103(-99) or (92-)88(-84) m.y., with some estimates slightly older, to 109 m.y. (Hengcheng Wang et al. 2009); Wikström et al. (2001) calibrated their tree on an age of ca 84 m.y. for this node, while Magallón and Castillo (2009) estimated an age of ca 102.4 m.y., Bell et al. (2010) an age of (110-)96 m.y.; (125.4-)124.5(-121.1) m.y. is the age in Xiang et al. (2014) and 125-98 m.y.a. in Xing et al. (2014). An age of 389-181 m.y. was suggested by Jeong et al. (1999) while almost the opposite extreme is the age of ca 89.7 m.y. in Naumann et al. (2013).

Evolution. Divergence & Distribution. Imperfect flowers pervade the two orders. However, flower type varies considerably in Anisophylleaceae, with perfect flowers occurring in Combretocarpus, as well as in fossils placed in href="../orders/fagalesweb.htm#Fagales">Fagales) and a few extant members of that order, so there may have been reversals of this character, or imperfect flowers have evolved more than once. "Embryo with large cotyledons" may be another synapomorphy (Zhang et al. 2006), also a three-carpellate gynoecium. However, ovary position and fruit characters in particular reverse spectacularly in this clade (see also Matthews & Endress 2004; Zhang et al. 2006), although Endress (2011a) thought that an inferior ovary might be a key innovation somewhere around here. See also Taylor et al. (2012) for additional possible apomorphies.

Phylogeny. For relationships, see above.

CUCURBITALES Berchtold & J. Presl  Main Tree.

(Frankia infection +, mechanism unclear); ellagic acid ?; storied fusiform cambial initials; perforation plates not or minimally bordered; tension wood?; rays wide, multiseriate; cuticle wax crystalloids 0; leaves spiral, lamina with secondary veins palmate; K or P valvate, stomata on K/P raised, the two whorls rather similar in texture; styluli +, (ovary with a roof, styluli often marginal); ovule with bistomal micropyle; codon changes [see Filipowicz & Renner 2010]. - 7 families, 129 genera, 2295 species.

Note: Possible apomorphies 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 partly because many characters show considerable homoplasy, in addition, basic information for all too many 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 is the not-so-trivial issue of how ancestral states are reconstructed (see above).

Age. The age suggested by Hengcheng Wang et al. (2009) for this node was (85-)80, 78(-73) m.y. (two penalized likelihood dates), while Bayesian relaxed clock estimates were slightly older, to 90 m.y.a..

Evolution. Divergence & Distribution. It is unclear where some of the features suggested by Filipowicz and Renner (2010) as being apomorphies of the order should be placed on the tree. Some, such as inferior ovary, are likely to characterize the [Cucurbitales + Fagales] clade, others, such as breeding system, are very labile and are perhaps more likely to characterize a clade within Cucurbitales. Zhang et al. (2006) also discuss aspects of morphological evolution and evaluate the extensive variation in breeding system in the clade.

Pollination Biology & Seed Dispersal. Zhang and Renner (2003) suggested that the flowers are usually imperfect, but perfect flowers are known from Anisophylleaceae. Indeed, breeding systems vary considerably in Cucurbitales, and Schaefer and Renner (2010) suggested that even within Momordica (Cucurbitaceae) there have been perhaps seven reversals from dioecy to monoecy - in a clade that is very approximately 35 m.y. old.

Plant-Animal Interactions. Butterfly caterpillars may be relatively uncommon on members of the order.

Chemistry, Morphology, etc. Cuticle waxes are usually not well developed. Possession of libriform fibres and slightly oblique end walls of vessel elements may be synapomorphies (Wagstaff & Dawson 2000, see also data in Nandi et al. 1998), as may banded wood parenchyma (Baas et al. 2000), homogeneous rays, and the possession of bitter compounds. Stipules are not placed as a synapomorphy of the order, although the data presented by Matthews and Endress (2004) might suggest that this was an option. However, not only does the morphology of the stipules in Anisophylleaceae and Corynocarpaceae need clarification, but the presence of stipules may be a synapomorphy at a much higher level (see rosids et al. above). Polarity of leaf venation is unclear, since Combretocarpus is sister to other Anisophylleaceae and Corynocarpaceae are sister to Coriariaceae; the first member of both pairs has pinnate venation, and the two clades are successively basal to the rest of the order.

More or less lacinate petals (and staminodes) are common in the order (Endress & Matthews 2006b). The thickness of the outer integument varies considerably. Matthews and Endress (2004, summarized in 2006b) provide an excellent survey of floral morphology of the group.

Phylogeny. For the circumscription of the clade see e.g. Setoguchi et al. (1999) and Schwarzbach and Ricklefs (2000). Coriariaceae and Corynocarpaceae are sister taxa, and their very similar wood anatomy is consistent with such a position (Carlquist & Miller 2001). However, other relationships remained poorly understood (Brouillet 2001 for some comments), although Zhang and Renner (2003a), using a variety of both chloroplast and nuclear genes, suggested that Anisophylleaceae were sister to the rest of Cucurbitales. Zhang et al. (2006) in a nine-gene study (all three compartments) confirmed these relationships and also placed Cucurbitaceae as sister to a [Tetramelaceae + Datiscaceae + Begoniaceae] clade, although relationships within this latter group were still not entirely clear. The clade [Datiscaceae + Begoniaceae] had at best only moderate support (Zhang et al. 2006; see also Schaefer et al. 2009; Schaefer & Renner 2011), but this topology is followed here - c.f. Soltis et al. (2007a) and Bell et al. (2010). For possible relationships between Tetramelaceae and Datiscaceae, see Swensen et al. (1994, 1998).

The relationships of the holoparasitic Apodanthaceae were for some time unclear (e.g. they are unplaced in A.P.G. 2009). Nickrent et al. (2004) suggested relationships either within Malvales (especially the three-gene analyses and that of nuclear SSU rDNA), or in or near Cucurbitales (analysis of matR), but inclined to the former position. Barkman et al. (2007: support weak, but rather comprehensive analysis) also suggested the latter position; the mitochondral genes cox1 and matR showed massive divergence, but not the atp1 gene (Barkman et al. 2007). Additional molecular analyses (D. Nickrent, pers. comm.; esp. Filipowicz & Renner 2010) support the position of Apodanthaceae in Cucurbitales. This is consistent with their dioecy, extrose anthers, inferior ovary and parietal placentation, all features common in Cucurbitales (see also Filipowicz & Renner 2010), but all these features are generally common in parasitic plants (Renner & Ricklefs 1995). There are also a number of codon subsitutions in common between Apodanthaceae and Cucurbitales (Barkman et al. 2007; Filipowicz & Renner 2010). The exact position of the family in Cucurbitales remains unclear, the relationships suggested with the morphologically rather different (but apomorphically so) Corynocarpaceae and Coriariaceae being only weakly supported, and Apodanthaceae are on a very long branch (Filipowicz & Renner 2010). The situation remained the same in Bellot and Renner (2014b), and in trees used when estimating substitiution rates Apodanthaceae linked either with a clade [Anisophylleaceae + Corynocarpaceae] or a clade including the whole of the rest of the family, but with a rather different topology to that used here; other topologies were also obtained, although none with strong support.

Previous Relationships. Cucurbitales are another rather unexpected assemblage of families. Coriariaceae have often been placed with families that have separate carpels and so were thought to be "primitive". Rhizophoraceae and Anisophylleaceae were often associated in the twentieth century, e.g. being placed in separate but adjacent orders, as in Takhtajan (1997), or even in the same family. However, although both were placed in Rosidae by Cronquist (1981), they were not adjacent. Indeed, morphological differences between the two are marked (e.g. Juncosa and Tomlinson 1988; Tomlinson 1988), and Rhizophoraceae are now securely placed in Malpighiales where they are sister to Erythroxylaceae; the two have much in common. Apodanthaceae have often been included in Rafflesiaceae s.l.

Similarities in floral morphology between Anisophyllea and Ceratopetalum (Oxalidales-Cunoniaceae: see Matthews et al. 2001; Endress & Matthews 2006b), although striking, are unlikely to be evidence of immediate close relationships of the two, even although the fossil Platydiscus peltatus seems to suggest similar relationships (Schönenberger et al. 2001a; see also Schönenberger & von Balthazar 2006); it was included in a study of Oxalidales by Heibl and Renner (2012).



Includes Anisophylleaceae, Apodanthaceae, Begoniaceae, Coriariaceae, Corynocarpaceae, Cucurbitaceae, Datiscaceae, Tetramelaceae.

Synonymy: Anisophylleales Reveal & Doweld, Begoniales Link, Coriariales Lindley, Corynocarpales Takhtajan, Datiscales Dumortier - Begonianae Doweld, Corynocarpanae Takhtajan, Cucurbitanae Reveal - Coriariopsida Parlatore, Cucurbitopsida Brongniart

ANISOPHYLLEACEAE Ridley   Back to Cucurbitales

Anisophylleaceae

Trees and shrubs; plants Al-accumulators; cork?; cambium storying?; nodes 1:1; cuticle waxes as platelets; stomata usu. paracytic; (serial [superposed] axillary buds +); branching from current growth, rythmic; lamina margins entire, (stipules 2-4, minute, at the very base of the petiole [= colleters?]); inflorescence branched, racemose or spicate; flowers small; K epidermis with mucilaginous inner walls, postgenitally coherent, C open (0), lobed or laciniate (entire), bundle number?, ± enclosing groups of A; A 2x K, obdiplostemonous, incurved in bud; nectary of separate lobes; G (stylulus hollow), compitum 0, stigma expanded or punctate; ovules often unitegmic, epitropous, outer integument 7-9 cells across, parietal tissue 1(?+) cells across, nucellar cap +; fruit 1-seeded, K persistent (slightly accrescent); embryo fusiform, largely hypocotylar; n = 7, 8; germination hypogeal.

4[list]/34. Pantropical (map: see Trop. Afr. Fl. Pl. Ecol. Distr. 1. 2003, 6. 2011; Clement et al. 2004). [Photo - Anisophyllea Fruit]

Age. Crown-group diversification in Anisophylleaceae may have begun (107-)85(-67) m.y.a. (Zhang et al. 2007).

1. Combretocarpus Bentham & J. D. Hooker

Indumentum lepidote [on flowers]; lamina with secondary veins pinnate; flowers perfect, 3(-4) merous; embryo sac sac bisporic [chalazal dyad], eight-celled [Allium-type]; fruit 3(-4) winged; cotyledons small.

1/1: Combretocarpus rotundus. Malesia: Malay Peninsula to Borneo.

2. The Rest.

(Cuticle waxes beaker-like - Polygonanthus); (leaves anisophyllous, appearing 2-ranked, lamina base asymmetric - Anisophyllea); plant monoecious (flowers perfect); flowers 4(-5) merous; nectary lobes also interstaminal; (roof over ovary, styluli marginal - Anisophyllea); ovule 1/carpel; fruit a drupe, (few seeded); testa multiplicative, 10-30 cells across, (vascularized), (mesotesta also lignified); cotyledons indistinct.

3/33: Anisophyllea (30). Pantropical, not E. Malesia to the Pacific.

Synonymy: Polygonanthaceae Croizat

Chemistry, Morphology, etc. Vincent and Tomlinson (1983) discussed the distinctive vegetative architecture of Anisophyllea, while Dengler et al. (1989) looked at the primary vascular organization of the orthotropic and plagiotropic shoots - quite different.

The staminate flowers of Anisophyllea disticha appear to have a semi-superior ovary with central styluli while the carpellate flowers have an inferior ovary, there is a roof on the ovary and the styluli are submarginal (Ruth Crevel, in Ding Hou 1858).

For further information, see Tobe and Raven (1987e, 1988a, c: floral morphology, embryology, fruit), Dahlgren (1988), Schönenberger et al. (2001a: fossils), Matthews et al. (2004: floral development) and Schwarzbach and Tomlinson (2011: general).

Phylogeny. Combretocarpus is sister to the rest of the family (Zhang et al. 2007), somewhat in conflict with morphology-based relationships (e.g. Tobe & Raven 1987c, 1988c); this may have an important effect on the polarity of characters in the family or even the order as a whole.

Previous Relationships. Anisophylleaceae were often linked with or included in Rhizophoraceae (Malpighiales: see above). However, the inner integument is ca 2 cell layers thick, there are no laticifers, the petals are not aristate, and a sclerified exotegmen is absent; in these and many other characters Anisophylleaceae differ from Rhizophoraceae (see Juncosa & Tomlinson 1988a, b).

[[Corynocarpaceae + Coriariaceae] [Cucurbitaceae [Tetramelaceae [Datiscaceae + Begoniaceae]]]]: uniseriate rays 0; filaments shorter than anthers in bud, anthers basifixed; nectaries 0; styluli +.

Age. Magallón and Castillo (2009) gave an age of ca 86.7 m.y. for this node, Bell et al. (2010) an age of (78-)67, 61(-48) m.y.. Wikström et al. (2001: c.f. topology) estimated an age of (68-)66, 65(-63) m.y..

[Corynocarpaceae + Coriariaceae]: ellagic acid +; wood with broad rays; sieve tube plastids lacking both starch and protein inclusions; stomata paracytic; lamina margin entire; flowers small, K quincuncial; C thick, base broad; G superior, ascidiate; ovule 1/carpel, outer integument vascularized; cotyledons very large.

Age. Wikström et al. (2001) suggested that this node was (55-)52, 48(-45) m.y.o., and Bell et al. (2010) that it was (64-)49, 43(-29) m.y.o..

Chemistry, Morphology, etc. For sieve tube plastids, see Behnke (1981c).

CORYNOCARPACEAE Engler, nom. cons.   Back to Cucurbitales

Corynocarpaceae

Trees; young stem with separate bundles; petiole bundles in a line; lamina vernation conduplicate, secondary veins pinnate, stipule single, intrapetiolar; inflorescence paniculate; calyx and corolla distinct; stamens = opposite and basally adnate to C, incurved in bud, staminodes 5, fringed, petal-like, opposite sepals, nectary basal, adaxial; pollen heteropolar, dicolpate, psilate, infratectum granular; G [2], transverse?, only 1 fertile, stylulus short, usu. single, conduplicate, stigma capitate, dry; ovule with outer integument ca 11[?-30] layers across; fruit a drupe, stylulus excentric; seed coat ?pachychalazal, initially thick, vascularized, becoming crushed; endosperm starchy; n = 22, 23.

1[list]/6. New Guinea to New Zealand, introduced on Hawaii (map: from van Steenis & van Balgooy 1966; Fl. Austral. 8. 1984). [Photo - Flower] [Photo - Fruit]

Chemistry, Morphology, etc. The cork develops from the cell layer beneath the epidermis. It is perhaps unclear whether the gynoecium is pseudomonomerous or unicarpellate. However, since some flowers have two styluli (e.g. Matthews & Endress 2004), the single, excentrically-placed structure at the apex of the gynoecium is called a stylulus and the gynoecium is pseudomonomerous {sic.]. The seeds are very poisonous, having bitter glucosides.

Some information is taken from Hemsley (1903: general), Nowicke and Skvarla (1983: pollen), Philipson (1987a: general), and Kubitzki (2011: general).

Previous Relationships. Corynocarpaceae were Celastralean in affinity according to Cronquist (1981), isolated, according to Takhtajan (1997), so here they are!

CORIARIACEAE Candolle, nom. cons.   Back to Cucurbitales

Coriariaceae

Usu. shrubs; roots with N-fixing Frankia; coriolic fatty acid [CH3(CH2)4CH(OH)CH=CHCH=CH(CH2)7COOH] in seed, sesquiterpenes, myricetin +; vessels in multiples, perforation plates bordered, true tracheids +, wood parenchyma (confluent) vasicentric; nodes 1:1; petiole bundle arcuate; buds usu. perulate; leaves opposite, lamina vernation ± flat, stipules small; plant polygamous or flowers perfect, inflorescences racemes; (flowers 6-merous), bracteoles 0; K quincuncial, C open, fleshy, often keeled adaxially; A 10, connective thin, septum between sporangia of theca not developed; tapetal cells 2-4-nucleate; pollen (2 colpate), starchy, (3-nucleate); G [5], opposite K, [(10)], stylulus slender, stigmatic all around, stigma dry; ovule apotropous, micropyle endostomal, outer integument 3-4 cells across, inner integument 2-3 cells across, parietal tissue ca 8 cells across, nucellar cap ca 4 cells across; fruitlets achenes [nutlets], several, surrounded by fleshy accrescent C; exotesta of cuboid, "tanniniferous", thick-walled, lignified(?) cells, rest undistinguished; n = 10, 15.

1[list]/5. Very disjunct: circum S. Pacific to China and Himalayas, Mediterranean (map: from van Steenis & van Balgooy 1966; Good 1974). [Photo - Inflorescence] [Photo - Fruit.]

Age. Fossils of Coriaria are known from about 33 m.y.a. (Saporta 1965).

Chemistry, Morphology, etc. Although the carpels seem to be separate, a compitum appears to be developed (Matthews & Endress 2004). There is but a single seed per carpel, but several seeds are produced by each flower.

Information on nodal anatomy is taken from Sinnott (1914), on embryology from Sharma (1968a), and on wood anatomy from Yoda and Suzuki (1992). For gynoecial development, see Guédès (1971), and for general information, see Kubitzki et al. (2011).

Phylogeny. For phylogenetic relationships within the family, see Yokoyama et al. (2000); the Eurasian clade is sister to the rest.

Previous relationships. Coriariaceae were placed in Ranunculales by Cronquist (1981) and as a monotypic Coriariales in Rosidae (Takhtajan 1997), largely because of their apparently separate carpels.

[Cucurbitaceae [Tetramelaceae [Datiscaceae + Begoniaceae]]]: perennial herbs; cucurbitacins [triterpenes] +, myricetin, ellagic acid 0; young stem with separate bundles; leaves with teeth, medial vein ending in a pad of packed translucent cells, lateral also entering [in Begonia lateral is dominant], stipules 0; flowers imperfect; G opposite sepals or median member adaxial, placentation parietal, a roof over the ovary, so styles marginal, stigmas large, elongated, bilobed; ovules many/carpel; seeds many/fruit.

Age. The age of this node has been estimated as (74-)62, 56(-43) m.y. (Bell et al. 2010), (69-)63(-61) m.y., i.e. late Cretaceous (Schaefer et al. 2009), or ca 57 m.y.a. (Naumann et al. 2013).

Chemistry, Morphology, etc. For information on leaf teeth, see Hickey and Wolfe (1975). The development of a roof over the ovary formed from tissue adaxial to the stylulus (Matthews & Endress 2004) is obvious when well developed; the styluli are then widely separate and borne towards the margin of the ovary. Matthews and Endress (2006) note details of ovule morphology that this group has in common.

CUCURBITACEAE Jussieu, nom. cons.   Back to Cucurbitales

Cucurbitaceae

Climbers, climbing by axillary tendrils, ± lateral, both branches and stem of tendril coiling; (silicon concentration high); alkaloids, bitter tetra- and pentacyclic triterpenoids, punicic acid [C18H30O2], non-protein amino acid citrullin [alpha-amino-delta-ureidopentanoic acid], saponins +, little oxalate accumulation, tannins 0; root cork superficial; stem cork variable in position; cambium storying?; extra-fascicular phloem +; vascular bundles initially in two rings [outer opposite the angles of the stem]; rays multiseriate; outer collenchyma and sclerenchymatous sheath in cortex; petiole bundle arcuate, or ring of arcuate bundles; no pericyclic sheath; (cuticle waxes as platelets); indumentum rough hairy/prickly, walls calcified, cystoliths + (0), hairs often glandular; leaves often with extrafloral nectaries, (lamina margins entire); plants dioecious (monoecious), inflorescences axillary; flowers ebracteolate or not, (3-)5(-7)-merous; hypanthium + (0; tube formed by adnation of K and C), short, K often connate, open, (0), C (induplicate-)valvate, connate; staminate flowers: nectary type?; A extrorse, variously connate [and forming a central column] or free [and well apart on the hypanthium], anthers monothecal; pollen grains prolate, to 40 µm long, (micro)striate, starchy; pistillode 0; carpellate flowers: staminodes +; G 1 [(2) 3(-5)], inferior, (median member abaxial), placentae intrusive, stigmas dry or wet, (channelled; not bilobed); ovules (1-few/carpel), pendulous; fruit a capsule, with a trifid apical opening; seeds flattened (not), pitted or not, testa multiplicative, complex, tegmen ± persistent, outer cells ± tracheidal; endosperm 0, chalazal haustorium + (0), cotyledons large, flat; germination epigeal (hypogeal - Momordica, etc.), seedlings with a peg [cortical outgrowth at the root-shoot transition].

98[list]/975 - five groups below. Largely tropical and subtropical, especially drier parts of Africa (map: from Heywood 1978 [N. part of range]; Saade 1998; Trop. Afr. Fl. Pl. Ecol. Distr. 1. 2003, 6. 2011; Florabase 2006). [Photos - Collection, Staminate flower, Carpellate flower, Fruit.]

"Fevilleoideae" Burnett - note - to be disposed of and the characters below to be integrated with the first few tribes as recognised by Schaefer and Renner (2011).

Axillary bud also present; (tendril unbranched); styluli +, marginal; epidermis unremarkable, hypodermal tissue ± thick-walled and lignified, inner sclerenchymatous layer several cells across, brachysclereidal, thickened, arenchyma with banded thickenings, inner layer +.

1. Gomphogyneae Bentham & J. D. Hooker

(Tendrils with adhesive pads); nectary of multicellular hairs on C; A 5, 1-thecal, 3, 2- or both 2- and 1-thecal, inserted at base of C and connate to middle of C; (pollen perforate-rugulate - Alsomitra); (fruit a berry); seeds with broad, membraneous wing (not); n = 11, 13.

6/56: Hemsleya (30). China and South East Asia to Australia and Fiji.

2. Triceratieae A. Richard

Nectary of multicellular hairs on C; A also 1-3, variously 1 or 2-thecal, inserted at base of C; (pollen larger, reticulate - Gerrardanthus); carpellate flowers: staminodia 5, (styles central); fruit circumscissile, with "longitudinal splits", 1(-3)seeded samara, or baccate; seeds narrowly winged or not; n = ?

5/24. Mostly tropical, New World (E. and S. Africa and Madagascar - Cyclanthopseris).

Synonymy: Nhandirobaceae Lestibudois

3. Zanonieae Bentham & J. D. Hooker

(Stalk of tendril coiled); (flowers weakly monosymmetric); nectary of multicellular hairs on C[?]; A 5 (4), 1-thecal, inserted at base of C to middle of tube; (pollen reticulate); seeds with membranous (narrow) wing; n = ?

4/12. Pantropical.

Synonymy: Zanoniaceae Dumortier

4. Actinostemma Griffith

Nectary of multicellular hairs on C; A inserted on base of tube, 5, or 2 pairs + 1, 1-thecal; style single; ovules 2-4, pendulous; fruit circumscissile, seeds winged or not; n = 8.

1/3. Central and East Asia.

5. The Rest.

Perennial or annual vines (lianes), (cauduciform [hypocotylar] succulents); additional non-protein amino acids +; tendrils complex, branches alone coiled [not Thladianthineae]; vascular bundles bicollateral; extrafascicular phloem system linked with adaxial phloem of bundles; staminate inflorescence + carpellate flower + bud + tendril making up axillary complex; plant monoecious; nectary parenchymatous, with stomata, (of multicellular hairs - Sicyoeae); staminate flowers: hypanthium well developed (short); A 5 [Luffa] or fewer, ?inserted, anthers often much bent and coiled, (locellate); pollen grains ± spherical, 40-70(-200: Cucurbiteae) µm long, ± spherical, reticulate, (colpate and [panto]porate; operculate; echinate); carpellate flowers: style single, shortly branched or not, stylar canal +, filled with secretion; ovules horizontal (to erect), micropyle endostomal or nucellus apex exposed, outer integument 6-15+ cells across, vascularized, inner integument (1-)2-5(-ca 6 - Bryonia, Sechium) cells across, parietal tissue 5-11 cells across, nucellar cap +; nucellar beak well developed [?level], suprachalazal region massive; antipodals degenerate; fruit ± fleshy, (irregularly dehiscent); seed not winged; exotesta enlarged, ± palisade or cubic, mucilaginous, hypodermal tissue various, sclereid layer sharply distinguished, single cell across, cells much enlarged, elongated or not, walls much thickened, walls of aerenchyma usu. unthickened, innermost layer chlorenchymatous; n = 9, 11, 12, 14 (etc.).

82/880: Trichosanthes (100), Sicyos (75), Momordica (60), Zehneria (60), Cucumis (55), Cayaponia (55), Cyclanthera (40), Gurania (37). Tropical to warm temperate.

Synonymy: Bryoniaceae G. Meyer, Cyclantheraceae Lilja

Evolution. Divergence & Distribution. The current world-wide range of the family is in large part the result of extensive dispersal, Madagascar being colonized an estimated thirteen times and Australia twelve times - and the latter currently has only twelve genera and thirty species of Cucurbitaceae (Schaefer et al. 2009). The secondarily woody Socotran endemic Dendrosicyos is dated to (30-)22(-14) m.y., although Socotra itself is only about ten m.y. old, which suggests that the clade now represented by just the single species was once on the mainland and has since become extinct there (Schaefer et al. 2009). Sebastian et al. (2012) suggested that there had been four westwards trans-Pacific dispersal events in the New World Sicyos alone. For more on dispersal in the family, see Duchen and Renner (2010).

Ecology & Physiology. Cucurbitaceae are very largely a group of climbing plants, whether lianes or vines, and are a prominent component of this vegetation element in the New World (Gentry 1991).

The phloem system in Cucurbitaceae is very complex. Fischer (1884) early noted that not all Cucurbitaceae had bicollateral vascular bundles (they are an apomorphy of only part of the family - see above). Taxa that do have bicollateral vascular bundles also have extrafascicular phloem (EFP) strands in the cortex outside the sclerenchymatous ring, although their development there is weak in taxa like Thladiantha and Momordica (Fischer 1884). EFP strands link with the adaxial phloem cells of the vascular bundles (Schmitz et al. 1987), but only at the nodes (Fischer 1883); in taxa like Cucurbita EFP strands permeate the cortex, even occuring in the collenchyma, and commissural strands are common (Fischer 1884). The sieve tubes of the EFP system differ in morphology from those of the fascicular phloem, although they may be similar to cells in the peripheral part of the latter (Crafts 1932).

When the plant is damaged, the copious phloem exudate comes largely from EFP, flow from the bundle phloem being blocked by callose almost immediately. The composition of EFP and fascicular phloem exudate is very different: Fascicular phloem exudate is rich in sugars and unidentified proteins, etc., EFP exudate contains P-proteins, amino acids, protein synthesizing machinery, and various secondary metabolites, but little sugar (Zhang et al. 2010). Zhang et al. (2012) found that phloem exudate came from different parts of the system in different species, although the completely extrafascicular sieve tubes were not involved. Not much of the exudate was from the fascicular phloem itself, and they thought that one of the functions of the P-protein in EFP exudate might even be to block the flow of water from the cut xylem as it congealed, although initially the water helped make large droplets of noxious (the exudate contains cucurbitacins - see below) and sticky exudate (Gaupels & Ghirado 2013). There is substantial evidence (Gaupels et al. 2012; see also Turgeon & Oparka 2010) that the EFP system is involved more in plant defence, and Gaupels et al. (2012) even thought that ecologically EFP exudate was like latex (see also Tallamy 1985; Konno 2011; Gaupels & Ghirado 2013). Interestingly, aphids feed on the abaxial phloem, and autoradiograms of minor veins suggest that abaxial phloem cells here are the sole conduits for carbon export and import, indeed, in the very finest veins there is no adaxial phloem system at all, i.e. the bundles there are collateral (Botha & Evert 1978; Schmitz et al. 1987; Hebeler 2000 and references).

More needs to be done to understand the complex vascular anatomy of the family, especially in the basal clades, to work out further details of how EFP is involved in plant defence, and how it links with the adaxial intrafascicular system. Much of the earlier work on phloem and phloem transport in Cucurbitaceae - because of the copious exudate, this had seemed to be an ideal system and has been much studied - actually has been carried out on EFP (Zhang et al. 2010)!

Pollination Biology & Seed Dispersal. There are a number of interesting pollinator-plant interactions in the family. Heliconius butterflies, whose caterpillars eat Passiflora vines (see Passifloraceae), are also closely associated with Psiguria (Cucurbitaceae), which they pollinate while at the same time obtaining nutrients from the pollen, probably by enzymatic activity of the saliva; the butterflies also visit some species of the closely related Gurania (e.g. Gilbert 1972, 1975; Boggs et al. 1981; Spencer 1988; Eberhard et al. 2009: see Steele 2010 for a summary and Steele et al. 2010 for a phylogeny of Psiguria). Interestingly, both Psiguria and Gurania have pollen grains in tetrads, alone in the family (Steele 2010). Psiguria in particular has very long-lived staminate inflorescences, and flowers are produced continuously for months or more. Other Cucurbitaceae, notably Momordica and Thladiantha, are oil flowers, the ca 19 extant species of Ctenoplectrini bees being associated with Cucurbitaceae and collecting material from the oil-secreting hairs, as well as pollen and nectar (Buchmann 1987; Vogel 1981b, 1990, 1997: variation in nectary morphology and secretion). Ctenoplectrini are an Old World group and are probably sister to the Eucerini; they may have diverged in the early Eocene ca 50 m.y.a. and now probably pollinate over 100 species of the family (Schaefer & Renner 2008b). Although Ctenoplectra bees visit Momordica, carpellate flowers in some species lack rewards (Schaefer & Renner 2010), deceit pollination?

Squash and gourd bees, some 20 species of the genera Peponapis and Xenoglossa, pollinate only species of Cucurbita. They feed early in the day, even flying in the dark pre-dawn hours (Hurd et al. 1971). They are attracted by particular floral volatiles, repelled by others which attract the cucumber beetles, while yet others seem to attract both herbivore and pollinator (Andrews et al. 2007). The bees, restricted to the Americas north of northern Peru, show some species-specific variation in pollen collecting devices (Hurd & Linsley 1964); Cucurbita can clearly be pollinated by a variety of bees since it is cultivated pretty much world wide. Within Cayaponia there have been shifts from bat to bee pollination, uncommon elsewhere in flowering plants (Duchen & Renner 2010). A number of taxa have elaborately fringed margins of their corolla lobes, while Momordica anigosantha has quite strongly monosymmetric staminate flowers, both in form and especially colour patterning, yet the carpellate flowers are less remarkable (Zimmermann 1922). Breeding systems in Cucurbitaceae can be very labile, with multiple reversals from dioecy to monoecy likely in Momordica (Schaefer & Renner 2010).

Plant-Animal Interactions. Low concentrations of the very bitter cucurbitacins, tetracyclic sterol-like triterpenes that are among the most bitter substances known to humans, elicit a compulsive feeding response from luperine beetles, including rootworm leaf beetles (Chrysomelidae-Galerucinae-Luperini: see Metcalf et al. 1980; Jolivet & Hawkeswood 1995). Gillespie et al. (2008) outline their phylogeny; there are some 4,000 species. 80% of the host plant records of the group are from Cucurbitaceae, and many species are pharmacophagous. That is, adults visit the flowers, feeding on pollen and sometimes other parts of the plant, and they sequester these bitter cucurbitacins (Eben 1999; Tallamy et al. 2005). The beetles are attracted by volatiles coming both from flowers and other parts of the plant (Andrews et al. 2007).

The larvae of some galerucines also feed on Cucurbitaceae, and this ability may have evolved independently in Old and New World members, Aulacophorina and Diabroticina respectively (Gillespie et al. 2003). The larvae sometimes cut leaf veins (they "trench" the leaves), so locally interrupting the translocation of cucurbitacins to the leaf tissue and so apparently allowing the insect to eat it (Dussourd & Eisner 1987). However, since at least some of these beetles will eat cucurbitacin crystals neat, physical avoidance of the copious sap produced by Cucurbitaceae is a more likely explanation of this feeding behaviour. Indeed, the concentration of cucurbitacins inside and outside the trench is about the same, but the sap is very rich in P-protein and eventually gels and so would probably thoroughly gum up the mouth parts, etc., of the beetle larvae if they ate untrenched leaves (McCloud et al. 1995; see also below).

The glandular hairs of Cucurbitaceae are another element of the defence of the plant against herbivores, quickly-solidifying secretions being produced when the trichomes are touched by insects (Kellogg et al. 2002). Discharge of the sap by these hairs may be explosive, Zimmermann (1922) mentioning what he called "Explosionshaare" in the family.

Larvae of a remarkable number of different Blepharoneura species (Diptera-Tephritidae [fruit flies]) are being discovered in flowers and fruits of neotropical Cucurbitoideae like Gurania. Some species are specific to staminate flowers, others to carpellate; all told some 52 species of flies were found on 24 species of cucurbits (Condon et al. 2008; Steele 2010 for Psiguria). It is estimated that there are around 200 species of Blepharoneura, all likely to be restricted to Cucurbitaceae (Norrbom & Condon) - perhaps the whole subfamily is. 14 species of these flies, on which there were 18 species of parasitoid wasps, were found in one site in Peru; they depended on two species of Gurania (Condon et al. 2014).

Butterfly caterpillars are not often found on members of this family (Ehrlich & Raven 1964).

Vegetative Variation. The tendrils of Cucurbitaceae are branched, and represent a branch complex. The length of the unbranched part of the tendril varies considerably, and the tendril may be ad- or abaxially curved in bud (Zimmermann 1922). Often there is a sublateral tendril + bud + slightly lateral flower associated with each leaf, or a tendril + vegetative bud + carpellate flower + staminate inflorescence, all more or less collaterally arranged, or other variants. Eichler (1875) and Goebel (1932) suggested that the tendril branches were prophylls, and in Bryonia dioica paired tendrils occur on the pedicel of an axillary flower (see also Zitnak et al. 2010). Non-flowering Zanonioideae have tendrils more or less lateral to vegetative axillary buds. When flowering finally begins, tendrils are replaced by more or less axillary flowers. The axillary bud produces an inflorescence branch that has an internode below the prophyllar leaf that subtends the first flower. Most Cucurbitoideae lack an initial prolonged vegetative period, and in one interpretation the inflorescence branch lacks a basal internode, so the first flower, often carpellate, arises in the leaf axil of the main branch and is subtended by a prophyll; the staminate inflorescence represents the development of this prophyllar bud (Lassnig 1997; axillary structures may be collateral in the vegetative part of the plant, sometimes superposed in the reproductive part). However, Gerrath et al. (2008) found that in Echinocystis lobata tendril, axillary bud, carpellate flower, and staminate inflorescence were all more or less independent in origin, although the latter two did arise from a common primordium (see also Zitnak et al. 2010). Joliffieae may be critical in understanding the evolution of the branch-tendril complex.

Gene & Genome Evolution. In Cucumis, at least, mitochondria (but not chloroplasts) are transmitted paternally (Havey et al. 1998). The mitochondrial genome is very variable in size, from ca 379,000-2,900,000 bp long, the shorter sequences, at least, having expanded by the acquisition of chloroplast sequences and the accumulation of numerous short repeats (Alverson et al. 2010).

Economic Importance. Cucurbitaceae were particularly important in early agriculture in the Americas, being one of the triumvirate of squash, corn and beans. For discussion of various aspects of the history of cultivation of Lagenaria and Cucurbita in particular, see Teppner (2004). For the domestication of squash (Cucurbita spp., inc. C. moschata and C. agyrosperma) which began ca 10,000 years ago, see Dillehay et al. (2007), Piperno et al. (2009) and Ranere et al. (2009); for phytoliths of the family, see Piperno (2006). Sebastian et al. (2010) suggest that the relatives of cucumber and melon (Cucumis) are Asian-Australian. Kistler et al. (2014) proposed that the pre-Columbian global distribution of the bottle gourd, Lagenaria siceraria, was in part caused by gourds drifting across the Atlantic from Africa to South America; seeds can remain viable for about a year in seawater, and simulations suggested that gourds could drift across the Atlanic between the equator and 20oS in less than this time. For the origin of watermelons (Citrullus), bedevilled by misidentifications in the past, see Chomicki and Renner (2014).

Chemistry, Morphology, etc. Cucurbitaceae produce phytoalexins only with difficulty (Harborne 1999). Raffinose is the main transport carbohydrate (Turgeon & Ayre 2005). Distinctive long-chain fatty acids occur in the seed oils; eleostearic acid, an isomer of punicic acid, is restricted to Joliffieae (Hopkins 1990). There are crystalloid inclusions in the protein bodies found in embryos of this family, perhaps unusual for flowering plants (Lott 1981).

A number of African Cucurbitaceae have swollen stem bases. The ring of fibres in the stems of Cucurbita, at least, has nothing to do with the vascular bundles (Blyth 1958). Acanthosicyos has paired thorns at the nodes, but I do not know anything about their development; Xerosicyos is a woody, succulent-leaved vine. Vascularisation of the leaf is complex, e.g. the leaf being supplied by one of the outer ring of bundles in its entirety and by branches from two other bundles of the outer ring, the bud being supplied by the inner ring (Sensarma 1955). Indeed, as the literature summarized by Sensarma (1955) suggests, there has been much speculation about the nature of the cauline vascular system and, related to this and based on how leaves are supplied from the cauline system, whether from the inner or inner + outer rings of bundles, on the presumed cauline versus foliar nature of the tendrils.

For the determination of the "sex" of the flower, see Chuck (2010). Flowers in taxa in which the androecium has two pairs of stamens and a single stamen, four stamens and a staminode (Gerrardanthus), etc., are strictly speaking monosymmetric. The petals of Xerosicyos are free; those of Echinocystis and Lagenaria at least have several traces. When the stamens are connate 2 + 2 + 1, the vascular supply shows evidence of this, although there are differences over the interpretation of the apparently bithecal stamens (e.g. de Wilde & Duyfjes 1999); Schaefer and Renner (2011) suggest that the plesiomorphic condition of the family is to have five bithecal stamens. Several tubes may arise from the one pollen grain (the pollen is polysiphonous), and some Cucurbiteae have very large almost spherical grains up to 200 µm or so long and across. The carpellate flower may have two rings of what can be interpreted as rudimentary anthers, while in the staminate flowers a ring of processes may alternate with the stamens. The nucellar beak is very large, in some specis abutting on to tissue of the placenta; depending on the species, the pollen-tube may swell up considerably there (Lizarazu & Pozner 2014). The chalazal haustorium of the embryo sac of Sechium [= Sicyos] edule, at up to 19,000 µm long, is apparently the longest in the family, although others are also quite long; only Santalales have longer embryo sacs (Mikesell 1990; Johri et al. 1992). Seedlings commonly have a peg, a cortical outgrowth towards the bottom of the hypocotyl at the root-shoot transition (e.g. Klebs 1884 for a list of taxa); this is not found in species in which germination is hypogeal (Zimmermann 1922).

For additional general information, see Jeffrey (1980), Bates et al. (1990), Jeffrey and de Wilde (2006) and especially Schaefer and Renner (2011a), for non-protein amino acids, see Fowden (1990), for cork cambium, see Dittmer and Roser (1963), for wood anatomy and secondary thickening, the latter odd, see Carlquist (1992c) and Patil et al. (2011), for seed coat anatomy, which is complex, Kratzer (1918), B. Singh (1972), D. Singh and Dathan (1973, 1974, 1998, 2001) and Teppner (2004), for embryology, etc., Kirkwood (1905), Warming (1913), Chopra (1955), Johri and Roy Chowdhury (1957), and Singh (1970), for floral morphology, etc., see Leins and Galle (1971) and Leins and Erbar (2010), for pollen, see Van der Ham et al. (2010: reticulate pollen derived?), and for general information, see .

Phylogeny. Renner et al. (2002) suggested that Cucurbitoideae were probably monophyletic, with Thladiantha possibly sister to the rest; tribes of Fevilleoideae (Zanonioideae) formed an unresolved basal polytomy. This was largely confirmed by Kocyan et al. (2007), although Indofevillea was sister to other Cucurbitoideae; monophyly of Fevilleoideae was not well suppported, Alsomitra sometimes appearing as sister to Cucurbitoideae. Schaefer and Renner (2008) also found that Fevilleoideae were paraphyletic and so did not recognise the subfamily. There may be a grade of four clades basal to a well-supported Cucurbitoideae, in which Indofevilleeae were well supported as being sister to the rest. This basal grade includeds Gomphogyneae, with only moderate support, where Alsomitra were sister to others in the tribe, a strongly supported Fevilleeae, Zanonieae, with 76% ML bootstrap, and a strongly supported Actinostemmateae; however, relationships between these clades had no support (Schaefer et al. 2009; Schaefer & Renner 2011). Fevilleoideae are not recognised here, but establishment of the phylogenetic relationships within the basal polytomy is important since it will considerably affect optimisation of characters on the tree.

Within Cucurbitoideae, phylogenetic studies suggest that Jeffrey's tribes (Jeffrey 2005) are largely monophyletic, although his subtribes are not (Kocyan et al. 2007). Jobst et al. (1998: ITS) found Benincaseae (Cucurbitoideae) to be polyphyletic; Chung et al. (2003) and Schaefer et al. (2008, esp. 2009: Alsomitra in Zanonieae) also looked at relationships within Cucurbitoideae. For smaller-scale studies within Cucurbitoideae, see Ghebretinsae et al. (2007), Wilde and Duyfjes (2006), Renner et al. (2007a), Schaefer et al. (2009), Schaefer and Renner (2010), Duchen and Renner (2010), Sebastian et al. (2010: Cucumis), and Sebastian et al. (2012: Sicyos).

Classification. For the suprageneric classification I follow Schaefer and Renner (2008a, esp. 2011b); in the latter there is provide a more comprehensive tribal classification which should be consulted for details (c.f. Jeffrey 2005).

There are many small genera in Cucurbitaceae, and generic limits need attention, thus Ghebretinsae et al. (2007) had to adjust the limits of Cucumis; see also Wilde and Duyfjes (2006), Renner et al. (2007a) and Schaefer et al. (2009). Sebastian et al. (2012) included 13 of these small genera in Sicyos.

Previous Relationships. Cucurbitaceae have usually been associated with other families that have parietal placentation, whether placed all together in Violales (Cronquist 1981) or in a group of small orders placed next to each other in Dilleniidae (Takhtajan 1997).

[Tetramelaceae [Datiscaceae + Begoniaceae]]: pollen spherical, stigmas elongated; fruit a septicidal capsule [dehiscing apically]; seeds with lid [operculate]; exotestal cells honeycomb, inner walls strongly thickened and lignified; cotyledons moderate in size.

Age. This node can be dated to (60-)57, 50(-47) m.y. (Wilström et al. 2001: c.f. topology).

Chemistry, Morphology, etc. Tebbitt (2005) suggests that the seeds of this group have a operculum or lid, but whether this is a synapomorphy or not is unclear. Seeds of Tetramelaceae are apparently unknown, and Boesewinkel (1984) found that the opercula of Datiscaceae and Begoniaceae were rather different.

See Mauritzon (1936b) for some details of the ovules, Clement et al. (2004) for testal morphology.

TETRAMELACEAE Airy Shaw   Back to Cucurbitales

Tetramelaceae

Trees; tannin 0; (wood fluorescing); (nodes with 2 traces from the lateral gaps); hairs glandular or lepidote; (lamina margins entire); plant dioecious; inflorescence spicate; K 4-8, postgenitally coherent; staminate flowers: C 0, or 6-8 [Octomeles], stamens = and opposite petals, incurved; carpellate flowers: C 0; G [3-8], (nectariferous disc on top), placentation axile, placentae bilobed [Octameles], stigmas undivided, decurrent to clavate; fruit also opening down the sides; seed coat?; n = ca 23.

Age. Tetrameles wood is known fossil from the Deccan Traps in India ca 70.6-65.5 m.y. old (Zhang et al. 2007).

2[list]/2. Indo-Malesia (map: from van Steenis 1953). [Photo - Tree]

Chemistry, Morphology, etc. Octomeles has sclereids; its capsular fruits split into two layers, the outer of which falls off. For general information, see Swensen and Kubitzki (2011, in Datiscaceae).

[Datiscaceae + Begoniaceae]: herbs; outer integument ca 2 cells across, inner integument ca 2 cells across.

DATISCACEAE Dumortier, nom. cons.   Back to Cucurbitales

Datiscaceae

Roots with N-fixing Frankia; cucurbitacins?; cambium not storied; medullary bundles +; tannin sacs +; nodes 1:3; leaves deeply divided to odd-pinnate, lamina vernation conduplicate, secondary veins ± pinnate; plant (andro)dioecious; inflorescence fascicles on racemose axis; P 4-10; staminate flowers: P valvate; A 6-25, outer members opposite P, filaments very short [anthers almost sessile]; pistillode 0; carpellate flowers: staminode 0; G [3-8], opposite P, styles elongated; ovules with parietal tissue 3-5 cells across, cap 2-3 cells across; embryo sac bisporic, 8-nucleate; fruit septicidal?; exotegmic cells large, cuboid; endosperm slight; n = 11.

1/2. W. North America, Crete to India (map: from Liston et al. 1989; Clement et al. 2004). [Photo - Flower, Flowers.]

Age. The age of crown-group Datiscaceae is somewhere around 50.5-26.5 m.y. (Liston 1997).

Chemistry, Morphology, etc. The lid on the seeds of Datisca is not surrounded by a ring of collar cells (Boesewinkel 1984: c.f. Begoniaceae). The stamens show no particular relationship to the calyx (Takhtajan 1997).

Much general information is taken from Davidson (1973, 1976) and Swensen and Kubitzki (2011); see Leins and Bonnery-Brachtendorf (1977) for floral development.

BEGONIACEAE C. Agardh, nom. cons.   Back to Cucurbitales

Begoniaceae

Fleshy herbs; tanniniferous, soluble oxalate accumulation; cork subepidermal; cortical (and medullary) bundles +; vessel elements also with scalariform perforation plates; nodes swollen; petiole bundles annular (central bundles +); no pericyclic sheath; sclereids and uncalcified cystoliths +; stomata anisocytic or with accessory cells in two rings [helicocytic]; hairs diverse, often prominent, flattened, pearl glands + [hairs spherical, multicellular, sessile]; leaves two-ranked, vernation laterally or vertically conduplicate (supervolute-curved [prophylls]), asymmetric, stipules +, large, cauline-extrapetiolar; inflorescence cymose, staminate flowers first produced ; K petal-like; staminate flowers: A many, centrifugal, connective enlarged; pollen colpate; carpellate flowers: placentae large, bilobed, stigmas twisted; ovules with parietal tissue 1-2 cells across, micropyle zig-zag, endothelium +; seeds minute, with lid and surrounding collar cells.

2[list]/1601. Largely tropical (map: from Trop. Afr. Fl. Pl. Ecol. Distr. 1. 2003, 6. 2011; Tebbitt 2005).

Age. the age of Hillebrandia, and hence crown-group Begoniaceae, has been estimated at 58.5-45 m.y. (Clement et al. 2004, errata 2005).

1. Hillebrandia

Plant ± tuberous; T 10, 2-whorled, inner [= "C"] very small; A often with branched vasculature; G [5], only partly inferior, placentation axile at base and parietal at top; n = ?

1/1: Hillebrandia sandwicensis. Hawaii (green in the map above). [Photos - Collection, also Begonia.]

2. Begonia

Plant rhizomatous (tuberous), (scandent; shrubby); leaves (spiral; opposite), (compound), (margins entire); (plant dioecious); (inflorescence racemose), (carpellate flowers first produced - Symbegonia group); staminate flowers: T in 2s, 2(3)4(-8); A 3-many, (connate), (porose); carpellate flowers: P (2-)5(-9); G [(1)2-3(-6)], placentation axile to parietal, (placentae not bilobed), styles central; capsule dehiscing laterally loculicidally (and septicidally), often asymmetrically winged, (fruit a berry); n = 8-21+.

1/1600. Largely tropical, but neither Hawaii nor the Antipodes (red in the map above). [Photo - Flower, Fruit.]

Evolution. Divergence & Distribution. Since Hillebrandia, from Hawaii, is sister to Begonia as a whole (see below), and its age has been estimated at 58.5-45 m.y. (Clement et al. 2004, errata 2005), this causes some biogeographical problems. Either Hillebrandia arrived from some continental area where it is now extinct, or it has been island hopping for 50 m.y. or more (for the ages of the island chain, see Sharp & Clague 2006 and references), or there was some combination of these scenarios (or Hillebrandia may be far younger than previously thought - Renner 2005).

The age for crown group Begonia may be 37.3-23.2 m.y. (Clement et al. 2004), although other estimates put diversification of the genus as occurring some time from the Eocene to early Oligocene 45-25 m.y.a. during a period of global cooling (Goodall-Copestake et al. 2009: sampling extensive) or (31-)24(-18.2) m.y.a. (95% HPD: Thomas et al. 2011b, focus on Malesia). Begonia may have originated in Africa, and sister to the South American and Southeast Asian clades that represent the rest of the genus (whatever the reconstruction) are seasonally adapted species with perennating organs (Goodall-Copestake et al. 2010). Thomas et al. (2011b) found several invasions of Malesia by Begonia and subsequently generally west-to-east movement. The main clade of Malesian species includes members of four sections, including the speciose section Petermannia, with at least 270 species; the age of that whole clade was (16.5-)11.5(-6.6) m.y. (95% HPD) (Thomas et al. 2011b). Sections in Begonia are generally limited to single continents, but the very recently described B. afromigrata, from Thailand and Laos but in a section otherwise known only from Africa, is an exception (de Wilde et al. 2011). Chinese species of limestone-inhabiting Begonia form a single clade, despite a variety of sectional assignments, and they diversified (11.7-)8.4(-5.3) m.y.a., perhaps 2 m.y. after the origin of the stem group of this clade (Chung et al. 2012).

Hughes and Hollingsworth (2008) suggested that the dearth of widespread species in Begonia is due in part to the low levels of gene flow (found in the few studies that have been carried out) and hence for the propensity of divergence in allopatry. De Wilde et al. (2011) drew attention to the broader distributions of those species of Begonia that had fleshy fruits compared to the narrower distributions of species with dry fruits - despite the fact that these latter species had minute seeds and perhaps might be supposed to be dispersed easily by wind.

Hillebrandia has a number of perhaps plesiomorphic features, and some of the features we think of as being characteristic of Begoniaceae as a whole (style position, fruit dehiscence) may in fact be apomorphies for Begonia alone.

Animal-Plant Interactions. Butterfly caterpillars are not often found on Begoniaceae (Ehrlich & Raven 1964).

Pollination Biology & Seed Dispersal. Staminate flowers of Begoniaceae produce pollen, carpellate flowers usually have no reward, but have bright yellow and anther-like stigmas; deceit polination is probably involved (Schemske et al. 1996; de Wilde 2001). There are a few ornithophilous species with nectaries at the base of the styles in carpellate flowers only, others have no reward at all; various levels of deceit/mimicry are again involved (Vogel 1998b; Renner 2006). Artificial hybridisation within Begonia has been extensive.

Tebbit et al. (2006) looked at the evolution of dispersal mechanisms in the speciose Southeast Asian Begonia; within a clade, taxa with animal or rain-ballist dispersal predominate. De Wilde (2011) discussed possible dispersal mechanisms in detail, and de Wilde et al. (2011) focussed on seed dispersal of fleshy-fruited members of the genus, which seem to have wider distributions than their dry-fruited congeners.

Genes & Genomes. There may have been a genome duplication somewhere near the base of the Begonia clade some 22 m.y.a. or more (Brennan et al. 2012).

Chemistry, Morphology, etc. The basic vegetative morphology of Begonia is interesting. There are various intermediates between trichomes, leaf teeth, and leaf-like appendages on the leaf; some taxa also have epiphyllous inflorescences (Dickinson 1978 for references). The leaf teeth are supplied by several veins.

Begoniaceae are somewhat unusual among monoecious taxa with cymose inflorescences in that the first flowers produced in the inflorescence are staminate, carpellate flowers being produced only later; the derived Symbegonia group has racemose inflorescences and shows the reverse arrangement (de Wilde 2011).

There are five small orange inner perianth parts (= "petals") in Hillebrandia that are very different from the large white outer perianth members (= "sepals"); the stamens are also orange... (Gauthier & Arros 1963). It has been suggested that the perianth of Begonia is to be compared with the sepals of Hillebrandia (see Gauthier 1959), and also that the petals of Hillebrandia are staminodial (Ronse Decraene & Smets 1990a, comparison with Papaveraceae), which they are in colour but not in position. The plesiomorphic tepal number of Begonia may be four in staminate flowers (a single whorl, c.f. Garcinia, or two bimerous whorls?) and five in carpellate flowers (Forrest et al. 2005). De Wilde (2011 and references) noted the variation in vascular supply to members of the perianth, while the vascular bundle to the stamen may be branched (Gauthier 1963). The stigmas are described as being antisepalous (Davidson 1973); any style is at most short.

For floral development, see Charpentier et al. (1989), for ovules, Boesewinkel and de Lange (1983), for placentation, de Wilde and Arends (1989), for seed morphology, de Lange and Bouman (1999 and references), and for a good general account, see de Wilde (2011).

Phylogeny. Hillebrandia, from Hawaii, is sister to Begonia as a whole (Clement et al. 2001; Swensen et al. 2001). For phylogenetic relationships within Begonia, see Plana et al. (2004), Forrest and Hollingsworth (2003) and Forrest et al. (2005). Thomas et al. (2011a), focusing on Asian Begonia, emphasized that several sections were para- or poplyphyletic, while Thomas et al. (2011b) showed that there had been several invasions of Malesia, including one now represented by members of four sections.

Classification. For a sectional classification, etc., of Begonia, see Doorenbos et al. (1998), and for the species of the genus, see Smith et al. (1986), Golding and Wasshausen (2002) and Tebbitt (2005: more horticultural).

Previous Relationships. Like Cucurbitaceae, Begoniaceae have usually been associated with the other families that have parietal placentation, whether placed in Violales (Cronquist 1981) or in a group of small orders placed next to each other in Dilleniidae (Takhtajan 1997).

[? + Apodanthaceae]: ?

Age. The age of a clade [Apodanthaceae [[Begoniaceae + Cucurbitaceae]] has been estimated as (91.9-)75.1(-58.6) m.y.o. by Naumann et al. (2013), while estimates for a stem age for the family ranged from (98-)81-65(-45) m.y.a. in Bellot and Renner (2014b).

APODANTHACEAE Takhtajan   Back to Cucurbitales

Apodanthaceae

Stem parasite, plant endophytic; vessel elements 0; stomata anomocytic; plant monoecious or dioecious; flowers fairly small; P +, 2-3(-4)-seriate, bi- or trimerous [e.g. 2 + 4 + 4 or 3 + 6 + 6], members of inner whorl with adaxial tufts of hairs; nectary +, at base of style/gynostemium; staminate flowers: gynostemium +; A synandrial, to 72 "pollen sacs", in 1-4 rings, no vascular bundles evident, extrorse, filaments 0, endothecium 0; pollen tricolpate, (apertures 0 - "Berlinianche"), psilate; pistillode +/0, vesicular hairs on margin (all over); carpellate flowers: staminodes 0; G [4 (5)], ± inferior, carpels opposite inner P, placentation parietal, style short, very stout, hollow, stigma ± hemispherical; ovules many/carpel, lacking vascular supply, micropyle bi/endostomal, or nucellus apex exposed, outer integument 1 cell across, inner integument 1-2 cells across, parietal tissue 0; antipodals persist?; fruit baccate; seeds minute; testa thin-walled, mucilaginous, exotegmen massively lignified; endosperm +, embryo undifferentiated; n = ± 12, 16, 30.

2[list]/10: Pilostyles (9). New World from the S. W. U.S.A. southwards, S. W. Asia, S. W. Australia and E. (mostly) Africa (map: from Fl. Austral. 8. 1984; Novoa 2005; Trop. Afr. Fl. Pl. Ecol. Distr. 5. 2010; Bellot & Renner 2014a - probably an underestimate, in Africa a parasite of e.g. the widespread Brachystegia and Julbernardia in Miombo woodland: White 1983 - and also mistaken for a rust...). [Photo - Flower.]

Age. The age of crown-group Apodanthaceae was estimated to be (77-)57-33(-25) m.y.a. (Bellot & Renner 2014b: high-end ages, some older than stem-group estimates, ignored).

Evolution. Ecology & Physiology. Recorded hosts include Fabaceae (Pilostyles) and Salicaceae (Apodanthes) (Bellot & Renner 2014a).

Pollination & Seed Dispersal. Apodanthaceae are pollinated by short-tongued flies and possibly by wasps, too, and the fruits are animal dispersed (Bellot & Renner 2013).

Genes & Genomes. For the much increased rate of variation in synonymous substitution in some mitochondrial genes, see Mower et al. (2007 and references). Barkman et al. (2007) found that mitochondrial genes (atp1) from host Fabaceae had moved to Pilosyles thurberi.

Chemistry, Morphology, etc. For the effect of Pilostyles on the wood structure of its host, Mimosa, see do Amaral and Ceccantini (2011).

There are cushions of hairs at the bases of the inner perianth parts. Interpreting the meristicity of the flower is not easy, and the androecium in particular is difficult to understand (Blarer et al. 2004).

For information, see Harms (1935a: general), Kuijt (1969: general), Rutherford (1970: esp. anatomy, cytology), Takhtajan et al. (1985: pollen), Visser (1981), Blarer et al. (2004: floral morphology). For vesicular cells, see Blarer et al. (2002, 2004) and for a detailed study of Pilostyles ingae, see Endriss (1902). The Parasitic Plants website (Nickrent 1998 onwards) and Heide-Jørgensen (2008) - both general - can be consulted with profit.

Phylogeny. For relationships within the family, see Filipowicz and Renner (2010).

Previous Relationships. Apodanthaceae, like other holoparasitic angiosperms, were often previously included in Rafflesiaceae s.l., Rafflesiaceae s.s. here is included in Malpighiales. Relationships of Apodanthaceae with Malvales have been suggested, some Malvaceae in particular lacking normal anther thecal structure, the androecium may be fused, etc. (e.g. Blarer et al. 2004; Endress & Matthews 2006a; Schönenberger & von Balthazar 2006).

Thanks. I am gratefull to S. Renner for comments.