EXTANT SEED PLANTS

Plant woody, evergreen; nicotinic acid metabolised to trigonelline; primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins rich in guaiacyl units; true roots present, xylem exarch; shoot apical meristem complex; arbuscular mycorrhizae +; stem with ectophloic eustele, endodermis 0, xylem endarch; vascular tissue in t.s. discontinuous by interfascicular regions; vascular cambium + [xylem ("wood") differentiating internally, phloem externally]; wood homoxylous, tracheids +; tracheid/tracheid pits circular, bordered; sieve tube/cell plastids with starch grains; phloem fibers +; stem cork cambium superficial, root cork cambium deep seated; nodes ?; leaf vascular bundles collateral; leaves spiral, simple, axillary buds?, prophylls [including bracteoles] two, lateral; plant heterosporous, sporangia eusporangiate, on sporophylls, sporophylls aggregated in indeterminate cones/strobili; true pollen [microspores] +, mono[ana]sulcate, pollen exine and intine homogeneous, ovules unitegmic, crassinucellate, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development endo/exosporic, gametes two, with cell walls; female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large", first cell wall of zygote transverse, embryo straight, endoscopic [suspensor +], short-minute, with morphological dormancy, white, cotyledons 2; plastid transmission maternal; two copies of LEAFY gene, PHY gene duplication, mitochondrial nad1 intron 2 and coxIIi3 intron present.

MAGNOLIOPHYTA

Plant woody, evergreen; lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, cyanogenesis via tyrosine pathway, lignins derived from both coniferyl and sinapyl alcohols, containing syringaldehyde [in positive Maüle reaction, syringyl:guaiacyl ratio less 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; stem with 2-layered tunica-corpus construction; wood fibers and wood parenchyma +; reaction wood ?, with gelatinous fibres; starch grains simple; primary cell wall mostly with pectic polysaccharides; tracheids +; sieve tubes eunucleate, with sieve plate, companion cells from same mother cell that gave rise to the tube, the sieve tube with P-proteins; nodes unilacunar; stomata with ends of guard cells level with aperture, paracytic; leaves with petiole and lamina [the latter formed from the primordial leaf apex], development of venation acropetal, 2ndary veins pinnate, fine venation reticulate, vein endings free; flowers perfect, polysymmetric, parts spiral [esp. the A], free, numbers unstable, P not differentiated, outer members not enclosing the rest of the bud, A many, development centripetal, with a single trace, introrse, filaments stout, anther ± embedded in the filament, tetrasporangiate, dithecal, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally by action of hypodermal endothecium, endothecial cells elongated at right angles to long axis of anther, tapetum glandular, binucleate, microspore mother cells in a block, microsporogenesis successive, pollen subspherical, binucleate at dispersal, trinucleate eventually, tectum continuous, endexine compact, lamellate only in the apertural regions, pollen tube elongated, with callose plugs, penetrating between cells, growth rate moderate, siphonogamy occuring, nectary 0, G free, several, ascidiate, with postgenital occlusion by secretion, few [?1] ovules/carpel, ovules marginal, anatropous, bitegmic, micropyle endostomal, integuments 2-3 cells thick, megasporocyte single, megaspore lacking sporopollenin and cuticle, chalazal, female gametophyte ?type, stylulus short, stigma ± decurrent, wet [secretory]; P deciduous in fruit; seed exotestal; double fertilisation +, endosperm ?diploid, cellular [first division oblique, micropylar end initially with a single large cell, chalazal end more actively dividing], copious, oily and/or proteinaceous, embryo cellular ab initio; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)_n]; whole genome duplication, 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 PHYA/PHYC gene pairs.

Possible apomorphies are in bold. Note that the actual level to which many of these features, particularly the more cryptic ones, should be assigned is unclear, because some taxa basal to the [magnoliid + monocot + eudicot] group have been surprisingly little studied. Furthermore, details of relationships among gymnosperms will affect the level at which some of these characters are pegged.

NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessels +, elements with scalariform perforation plates; pollen tectate-columellate, tectum reticulate [perforated]; nucleus of egg cell sister to one of the polar nuclei; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.

PROTEALES [TROCHODENDRALES [BUXALES [GUNNERALES + CORE EUDICOTS]]]: ?

TROCHODENDRALES [BUXALES [GUNNERALES + CORE EUDICOTS]]: benzylisoquinoline alkaloids 0; euAP3 + TM6 genes [duplication of paleoAP3 gene: B class], mitochondrial rps2 gene lost.

BUXALES [GUNNERALES + CORE EUDICOTS]: ?

GUNNERALES + CORE EUDICOTS: Ellagic and gallic acids common, cyanogenesis via phenylalanine, isoleucine or valine pathways; micropyle?; PI-dB motif +, small deletion in the 18S ribosomal DNA common.

CORE EUDICOTS: Root apical meristem closed; flowers rather stereotyped: 5-merous, parts whorled, K and C distinct, K with 3 traces, A = 2x K, internal to the C whorl, (numerous, but then often fasciculate and/or centrifugal), pollen tricolporate, (nectary disc +), [G 5], [3] also common, compitum +, placentation axile, stigma not decurrent; endosperm nuclear; fruit dry, dehiscent, loculicidal [when a capsule]; euAP1 + euFUL + AGL79 genes [duplication of AP1/FUL or FUL-like gene], PLE + euAG [duplication of AG-like gene: C class], SEP1 + FBP6 genes [duplication of AGL2/3/4 gene].

SAXIFRAGALES [VITALES + ROSIDS]: Stipules +.

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

ROSIDS   Back to Main Tree

(Nectary receptacular); embryo long; genome duplication; chloroplast infA gene defunct, mitochondrial coxII.i3 intron 0.

The age of the rosid clade has been estimated at 117-108 million years before present (Wikstr&m et al. 2003); fossils assignable to rosids are ca 94 my (Crepet et al. 2004). The age of the rosids in Anderson et al. (2005) should be treated with caution, since members of both Vitales and Crossosomatales were included in their rosids - and there was also a separate Crossomatales. Butterfly caterpillars are common on members of the group, occuring about twice as frequently as might be expected going by species number alone, but the tree habit is also common in the group, and trees perhaps support a correspondingly disproportionate number of larvae... (Janz & Nylin 1998).

Smets et al. (2003) characterise the rosids as having receptacular nectaries; note that the Vitales have gynoecial nectaries and Proteaceae have receptacular nectaries (Smets 1988).

The limits and relationships of the rosids are unclear. D. Soltis et al. (2003a) found 79% support for the clade, but rosids may also include Vitales and Saxifragales, the latter being sister to the rest of the group (e.g. P. Soltis et al. 1999: Vitales not included), albeit with weak support. See the Berberidopsidales page for further discussion on the relationships of the rosids. Whether or not they include Saxifragales and Vitales, they have no firm position as yet, yet it does seem that Vitales may well be sister to them (e.g. Jansen et al. 2007). Within rosids, relationships are also somewhat unclear (e.g. Soltis et al. 2005b; Jansen et al. 2006a; Bausher at al. 2006; Zhu et al. 2007), and the topology in the tree here may need adjustment; the composition of the rosid I clade is perhaps particularly problematical. In an analysis including the mitochondrial matR and two chloroplast genes, [Celastrales + Oxalidales + Malpighiales] were sister to the N-fixing clade, with weak to moderate support; Crossosomatales were weakly supported as sister to the rosid II clade, while Myrtales and Geraniales may be successively sister to all other rosids - but with little support. Vitales and Saxifragales were successively basal to this whole group (Zhu et al. 2007). [Myrtales + Geraniales], a clade with weak support, were found to be sister to rosid II clade, the combined clade having strong support (weaker using maximum parsimony) and in turn being strongly supported as sister to the [N-fixing clade + [Celastrales, Oxalidales, Malpighiales]] clade, albeit with sketchy sampling (Jansen et al. 2007).

The feature of cuticle wax platelets as rosettes is scattered through this group, but is especially common in Fabaceae and is known from several Malpighiales (see Ditsch & Barthlott 1997 for details). Distinctive mucilage cells in flowers with a much thickened mucilaginous inner periclinal wall and distinct cytoplasm are found especially in this broader group (note: not yet reported from Geraniales, see Matthews & Endress 2006b). The sepals characteristically have three traces from three gaps; in several more basal eudicot clades the outer perianth/sepals have only a single gap (von Balthazar and Endress 2002 - see also Ranunculales). Petal development is often retarded relative to that of other parts of the flower (also in Cabomba and Saruma!). For the genome duplication, see Tuskan et al. (2006); exactly where it is to be placed on the tree is unclear. Similarly, where the loss of the chloroplast infA gene is to be placed is unclear (see Millen et al. 2001).

Unplaced:  Back to Main Tree

PICRAMNIACEAE Fernando & Quinn

Trees; bark bitter or very bitter; C₁₈ acetylenic acids [tariric, petroselenic], anthraquinones, anthracenone moieties linked to C₅-sugar derivatives +; vessel elements with simple perforations; leaves spiral, odd-pinnate, conduplicate, leaflets often ± alternate, extrafloral nectaries +, stipules 0; plant dioecious, inflorescence racemose, flowers 3-5(-6)-merous, small, K connate basally (free); staminate flowers: A = and opposite C, pollen?, disc, pistillode minute; carpellate flowers: staminodes [?nectariferous] +, G [2-3], 2 ovules/carpel, micropyle ?bistomal, styles recurved, pointed; endosperm ?development; n = ?

2[list]/46. Neotropical.

Picramnioideae Engler

Ovules epitropous, apical; fruit a berry; seed coat ca 6 cells across, vascularised, unlignified, or two subepidermal layers lignified, inner layers crushed; embryo minute.

1/41. S.E. USA, Central and South America, Caribbean (Map: from Pirani 1990). [Photo - Fruit]

Picramnia may have unilacunar nodes with three or more traces (M. Ogburn, pers. comm.)

For seeds, see Picramna sellowiana (Vásquez & Jaramillo 11419) and P. latifolia (Aguilar 5020).

Alvaradoideae Liebm.

Vascular tracheids +; staminate flowers: C usu. 0; carpellate flowers: staminodes opposite K, only 1 G fertile, ovules apotropous, basal; fruit a samaroid capsule; exotesta resinous, endotegmen as a resinous membrane; endosperm 0, cotyledons large.

1/5. Florida, Central America, Bahama, esp. the Greater Antilles, Bolivia to Argentina (Map: from Thomas 1990). [Photo - Fruit]

For some chemistry, see Villatoro et al. (1974), and for seeds, see Núñez et al. 83.

• Picramniaceae are often rather small trees with bitter-tasting bark and spirally-arranged, compound leaves; the leaflets alternate along the rachis. The small flowers are born in a raceme, and the stamens are equal to and opposite the petals.

The bitter taste in the bark is probably caused by the presence of sugar-linked anthracenone derivatives (Jacobs 2003). Indeed, Jacobs (2003) emphasizes the distinctive nature of their secondary metabolites, these anthracenone moieties linked to C₅-sugar derivatives apparently being unknown in any other plants and the C₁₈acetylenic acid, tariric acid, is also unknown from other flowering plants (see also Bohlmann et al. 1973).

The family is very poorly known; I have seen only Picramnia in the field. Xylem parenchyma is rather scanty to absent. Fiber tracheids dominate, but Alvaradoideae commonly have vascular tracheids (Webber 1936). The hairs are unicellular and have distinctive golden contents (M. Ogburn, pers. comm.).

Picramniaceae were placed between Rosid I, which includes Surianaceae and Irvingiaceae (ex Simaroubaceae), and Rosid II, which includes Simaroubaceae themselves, by Fernando et al. (1995), but in the past they have usually been placed within Simaroubaceae (e.g. Cronquist 1981; Takhtajan 1997).

For general information, see Fernando and Quinn (1995) and Kubitzki (2006b), and for chemistry, see Hegnauer (1973, 1990, as Simaroubaceae) and especially Jacobs (2003). Rao (1970) briefly mentions the seed coat of Alvaradoa.

Synonymy: Picramniales Doweld

CROSSOSOMATALES Reveal  Main Tree, Synapomorphies.

?Nodes; leaf margins toothed, stipules cauline; hypanthium +, with nectary [disc], G stipitate, ovules apotropous, micropyle bistomal [zig-zag], both integuments 4 or more cells across, styles free, compitum present only near stigma [i.e. postgenital connation occurs here], stigma wet; seed testal, walls of outer layers much thickened. - 8 families, 12 genera, 66 species.

Estimates of the age of this clade are in the order of 104-97 million years before present, with divergence beginning 95-91 million years before present (Wikström et al. 2001).

The petals usually have but a single trace. The inner integument in particular may be only three cells thick (Crossosoma, Geissoloma).

There is some support for placing Crossosomatales as sister to the malvid group (Huerteales, Sapindales, etc.: see Zhu et al. 2007). Crossosomatales are a surprising group, but they are likely to be monophyletic. Details of some of the relationships in the tree below like [[Aphloiaceae + Ixerbaceae] [Staphyleaceae [Stachyuraceae + Crossosomataceae]]] (D. Soltis et al. 1999, 2000; cf. in part Koontz and Soltis 1999) and [[[Crossosomataceae + Stachyuraceae] Staphyleaceae] Geissolomataceae] (rbcL tree in Nandi et al. 1998) have been suggested; see also Savolainen et al. (2000a). The tree is based on these studies, and also that of Sosa and Chase (2003) and Oh and Potter (2006). Although some relationships within the group remain unclear, and Crossosomatales as a whole are not very strongly supported (but 1.0 p.p. in Soltis et al. 2007a), the similar and distinctive seed coat anatomy of all the included members is a morphological feature uniting it. Furthermore, despite the apparently rather heterogeneous nature of Crossosomatales, Matthews and Endress (2005a, also 2006b for a summary) emphasise the number of distinctive features of the order, even if exactly where some of these are to be placed on the tree is unclear. For instance, the funicular vascular bundle ends undivided in the chalaza in Stachyuraceae and Staphyleaceae, whereas it splits into 3-6 short bundles in the other families (Geissolomataceae were not studied). Is a divided bundle an apomorphy for the order (or larger group), lost in the Staphlyeaceae-Crossosomataceae clade, and so a synapomorphy for it, but then regained in Crossosomataceae itself? Or is its distribution to be explained by some other combination of gains and losses (the distribution of "luminous" stylar canals and loculi may be the same)? Of course, more detailed study of this character may change the question. Matthews and Endress (2005a, 2006b) also note that there is much more in common between members of Crossosomatales in the broad sense (as delimited below) than in the three families included in narrow circumscription of the order (Crossosomataceae, Stachyuraceae, Staphyleaceae). Recently the distinctive Guametala has been added to Crossosomatales (Oh & Potter 2006: three genes); it has strong support as sister to [Stachyuraceae + Crossosomataceae]. All in all, however, this is a remarkably heterogeneous group, as Oh and Potter (2006) discuss as they rather reluctantly decide to place Guamatela in a monotypic family; ultimately, however, some merging of families will be in order.

Does Gumillea (ex Cunoniaceae) belong here?

For the distribution of characters of floral morphology in the group, I largely follow the excellent study by Matthews and Endress (2005a), which should be consulted for more details, alternative interpretations of states, etc. For a survey of wood anatomy, with a listing of the features - possibly plesiomorphic - common to the whole order, see Carlquist (2007c).

Includes Aphloiaceae, Crossosomataceae, Geissolomataceae, Guamatelaceae, Ixerbaceae, Stachyuraceae, Staphyleaceae, Strasburgeriaceae.

Synonymy: Geissolomatales Reveal, Ixerbales Doweld - Crossosmatanae Doweld

Staphyleaceae [Guamatelaceae [Stachyuraceae + Crossosomataceae]]: leaves or leaflets involute; inflorescence terminal; stigma ± expanded.

The age of Crossosomatales (stem group 89-83 million years before present, crown group 47-40 million years before present) properly refers to this clade (see Anderson et al. 2005).

STAPHYLEACEAE Martynov, nom. cons.   Back to Crossosomatales

Evergreen to deciduous shrubs to trees; ellagic acid 0; wood often fluorescing; fibers with bordered pits; nodes 3:3, 5:5; petiole bundles annular; mucilage cells +; stomata anisocytic; cuticle waxes as (parallel) platelets; leaves opposite, odd-pinnately compound (uni-, trifoliolate), "glands" or stipels at articulations, stipules interpetiolar or not; K subpetaloid, A = and opposite K, anthers sagittate, pollen microreticulate, G [2-3(4)], odd member adaxial, with (1-)6-12 (basal) ovules/carpel, orientation variable, nucellar cap +; fruit a berry, dry inflated and indehiscent, or follicle [Euscaphis], K persistent or not; seeds few, testa multiplicative (vascularised), exotesta palisade (not), mesotesta thick-walled, endotesta slightly thick-walled, unlignified; embryo green, cotyledons large; n = (11-)13(-14).

2[list]/45: Staphylea (23), Dalrympelea (20-25). North temperate, tropics in America (to Bolivia) and Malesia (Map: see van der Linden 1960; Meusel et al. 1978 - esp. inaccurate in South America). [Photo - Fruit, Staphylea Flower, Fruits.]

• Staphyleaceae are shrubs to trees that may be recognised by their opposite, odd-pinnately compound leaves with serrate leaflets and little "glands" at the articulations (the latter often collapse when dry), the stipules are cauline and are sometimes interpetiolar. The flowers have rather petaloid sepals and usually two to three carpels.

Dickison (1987b) noted the distinctive nodal anatomy of the family, with small accessory traces going to the leaves. The pollen is binucleate according to Kimoto and Tokuoka (1999). The limits of the genera currently accepted are unsatisfactory (Simmons & Panero 2000).

Staphyleaceae were placed in Sapindales by Cronquist (1981) and Takhtajan (1997). Tapiscia and Huertea have long been recognised as being rather different from other members of the family, i.a. having spitally-arranged leaves (see Dickison 1987 for a convenient table of differences): molecular data suggest that they are not at all closely related and here they are placed in Huerteales.

See Hegnauer (1973, 1990: chemistry), Carlquist and Hoekman (1985: wood anatomy), Dickison (1986: floral morphology, 1987a: pollen morphology, 1987b: vegetative anatomy), Ramp (1987: gynoecium), Danilova (1996: seed structure), and Simmons (2006: general).

Synonymy: Ochranthaceae Endlicher

Guamatelaceae [Stachyuraceae + Crossosomataceae]: funicular aril +.

GUAMATELACEAE S. Oh & D. Potter   Back to Crossosomatales

Sprawling evergreen shrub; ellagic acid ?; nodes 3:3; petiole bundles annular; stomata ?; leaves opposite, ?vernation, venation palmate; K coloured, C spathulate, A 10, anthers sagittate, pollen membranes protruding through apertures, surface microreticulate, G 3, many biseriate ovules/carpel; fruit a follicle, K persistent; seeds many; endosperm scanty; n = ?

1/1 (Guamatela tuerckheimii). Mexico, Guatemala, and Honduras.

• Guamatelaceae are sprawling shrubs with opposite, stipulate, serrate leaves that have palmate venation and a densely whitish tomentose lower surface. The flowers have sepals and petals almost equal in size, ten stamens, and three carpels connate only by the tips of their styles. The fruit are follicles and are almost enclosed by the persistent sepals.

The anatomy, embryology, and chemistry of this genus are largely unknown.

Guamatela used to be included in Rosaceae (Oh & Potter 2002 [exact position still uncertain]; Potter 2003), and it does indeed look faintly Rubus-like.

Stachyuraceae + Crossosomataceae: crystals/druses absent from flowers, anthers X-shaped; whole testa sclerotic.

It has been suggested that Stachyuraceae and Crossosomataceae diverged 68.25±10.36 million years before present (Zhu et al. 2006).

STACHYURACEAE J. Agardh, nom. cons.   Back to Crossosomatales

Evergreen or deciduous shrubs or small trees; ellagic acid +; true tracheids +; petiole bundle arcuate; hairs eglandular, (cuticle waxes as tubes); stomata paracytic; leaves spiral; inflorescences axillary, racemose, flowers 4-merous, K decussate, A 2x K, pollen (trinucleate), psilate, hypanthium 0, nectary at base of G, G [4], opposite K, placentation intrusive apical-parietal, many biseriate ovules/carpel, style +, short, compitum down style; fruit a berry, K deciduous; seeds many, coat multiplicative, tegmen obliterated; embryo moderate, cotyledons large; n = (11) 12.

1[list]/5. South East Asia (Map: from Li 1943; Chen 1981). [Photo - Habit/Fruits, Inflorescence]

• Stachyuraceae are small trees or shrubs with closely serrate, stipulate leaves and rather long, pendulous, racemose inflorescences. The sepals and petals of the four-merous flowers are similar, and the fruit is a berry.

The leaves have veins running to opaque, deciduous teeth. The stomata are reported as being anomocytic (Schneider 2006). Although the flowers appear to be perfect, Schneider (2006) suggests that crypric dioecy may be the norm. The micropyle is zig-zag. For pollen, see Jin and Wei (2002); they describe the surface as being foveate and the grains as being 18-28µm in size, larger than those of Tapiscia (see Tapisciaceae, Huerteales) but smaller than the finely reticulate grains of Staphyleaceae (28-40µm).

Stachyuraceae were included in Theales by Takhtajan (1997).

Details of the flower are taken from Hooker (1882) and of embryology from Mathew and Chaphekar (1977) and Kimoto and Tokuoka (1999); see Hegnauer (1973, 1990) for chemistry, Chen (1981) for a revision of most of the species, Schneider (2006) for general information, and Zhu et al. (2006) for a phylogeny.

CROSSOSOMATACEAE Engler, nom. cons.   Back to Crossosomatales

Deciduous shrubs; inulin, ellagic acid +; vessel elements with simple perforations; nodes also 1:1; yellow acicular crystals common; leaves spiral or opposite (entire), stipules minute, petiolar or 0; (plant polygamo-monoecious); inflorescence also axillary; flowers (3-)4-5(-6)-merous, (nectary 0), A 4-many, opposite K or from 10 trunk bundles, tapetal cells polyploid, pollen microreticulate, G 1-5(-9), odd member adaxial, (1-)2-many amphi- or campylotropous ovules/carpel, archesporium multicellular, styles short, stigma also decurrent; follicle coriaceous; aril fimbriate, endotegmen fibrous; n = 6.

4[list]/12. W. North America (Map: from Hannon 2002). [Photo - Crossosoma Collection]

• Crossosomataceae are rather small-leaved, much-branched deciduous shrubs that are otherwise vegetatively nondescript. The flowers have separate sepals, petals and carpels and a more or less well developed hypanthium. The fruits are follicles and the seeds have a fimbriate aril.

Velascoa has a long hypanthial tube, but it apparently lacks a nectary.

Crossosomataceae were included in Rosales by Cronquist (1981) and were sister taxon to Geraniaceae in some early molecular studies (e.g. Price & Palmer 1993).

Information is taken from Hegnauer (1964, 1989: chemistry), P. E. Richardson (1968: general), Kapil (1970: embryology, etc.), DeBuhr (1978: wood anatomy), Tatsuno and Scogin (1978: chemistry), Thorne and Scogin (1978: inclusion of Forsellesia), Rzedowski and Rzedowski (1997: new genus), Hannon (2002: review), Sosa and Chase (2003: phylogeny) and Sosa (2006: general summary).

Aphloiaceae + Geissolomataceae + Ixerbaceae + Strasburgeriaceae: conspicuous protrusions from pollen apertures.

APHLOIACEAE Takhtajan   Back to Crossosomatales

Evergreen shrubs or trees; cork pericyclic; tracheids dimorphic; rayss of two different widths; stomata anisocytic; petiole bundles arcuate; plant glabrous; leaves 2-ranked; inflorescence fasciculate; P ca 7, ?spiral, A many, pollen striate, G 1, ca 10 ovules/carpel, micropyle endostomal, stigma sessile, annular-peltate-bilobed; fruit a berry, P and A persistent; outer 3-5 testal layers much thickened, then small unthickened cells, then 2-3 layers of elongated unthickened cells; endosperm development?; embryo curved, terete; n = ?

1/1 or more: Aphloia theiformis. E. Africa, Madagascar, the Mascarenes and Seychelles (Map: from Serban Procheŝ, pers. comm.). [Photo - Fruit]

• Aphloiaceae are undistinguished evergreen shrubs or small trees with distichous, serrate leaves and often persistent stipules. The axillary flowers have a hypanthium, an undifferentiated perianth, many stamens, and a single carpel. Herbarium specimens have a yellowish, crusty material associated with them, rather like some Thymelaeaceae.

The hypanthial region is broad and spreading and its surface may be nectariferous. The ovules are possibly campylotropous, and are not simply anatropous.

Aphloia used to be included in Flacourtiaceae; it was included in Violales by Takhtajan (1997).

Details of the seed coat are in part taken from Takhtajan (1992) while Hegnauer (1989, as Flacourtiaceae) gives a few details of plant chemistry; see Kubitzki (2006b) for a summary.

Geissolomataceae [Ixerbaceae + Strasburgeriaceae]: hairs single-celled, lignified and T-shaped; pollen ± psilate; G not stipitate, alternate with P/K, with abaxial [dorsal] ribs, two collateral pendant ovules/carpel, stigma punctiform [formed from postgentitally united twisted stylesl tips]; fruit a capsule; hilum on seed large.

GEISSOLOMATACEAE Endlicher, nom. cons.   Back to Crossosomatales

Evergreen shrubs; plants Al-accumulators; cork outer cortical; nodes 1:1; leaves opposite, margins entire, 2ndary veins palmate, paired projections [?stipules] on petioles; flowers axillary, 4-merous, with 3-4 pairs of basal bracts, P 4, petaloid, basally connate, A adnate to base of P, G [4], micropyle exostomal, styles slender; fruit surrounded by persistent K; seed with funicular caruncule, coat with thick-walled cells; endosperm development?, embryo ?small, cotyledons thin; n = ?

1[list]/1 (Geissoloma marginatum). Cape Province, South Africa (Map: from Heywood 1978).

Geissolomataceae were included in Celastrales by Cronquist (1981), in Ericanae by Takhtajan (1997).

For information on nodal anatomy, R. A. Howard (pers. comm.); general information is taken from Baillon (1875), Dahlgren and van Wyk (1988, "micropyle endostomal", but cf. Stephens (1910) and Forest (2006), seed coat from Danilova (1996).

Ixerbaceae + Strasburgeriaceae: cells with thickened mucilaginous inner tangential walls [in flowers, at least]; acicular crystals +; leaves spiral, margins gland-toothed; flowers large; K spiral, C clawed, filaments flattened, anthers >3mm long, ovules sessile, epitropous, style long, hollow; style persistent in fruit; x = 25.

For general information, see Cameron (2003).

IXERBACEAE Doweld & Reveal   Back to Crossosomatales

Evergreen trees; non-hydrolysable tannins 0; cork?; pits vestured; petiole bundles arcuate; stipules 0; inflorescence terminal, umbellate; A = and opposite K, pollen 4-5-colporate, disc lobed opposite C, G [5], funicular obturator +, style strongly ridged and obviously spiral at apex; carpels also splitting adaxially, valves woody, reflexed, K deciduous; seeds shiny, with a broad "aril", hilar scar elongated, exotestal and adjacent cells thickened; endosperm development?, cotyledons large; n = 25.

1/1 (Ixerba brexioides). North Island, New Zealand.

• Ixerbaceae are evergreen trees with pseudoverticillate and strongly toothed but estipulate leaves. The inflorescences are terminal and the flowers are rather large and have five spreading sepals and petals, ten stamens with thick connectives, and a conspicuous ovary gradually tapering into the style and with a spreading, lobed nectary at its base. The pointed capsular fruit has a few shiny black seeds with a conspicuous red aril.

Glands like those of leaf margin are in a cauline stipular position in seedlings. The vascular bundles in the receptacle are clustered.

Ixerba was placed in Grossulariaceae by Cronquist (1981), in Brexiaceae by Airy Shaw (1966: note the specific epithet), and in Rosidae-Brexiales by Takhtajan (1997).

Details of anatomy are taken from Gregory (1998: in Escalloniaceae) and Hils (1985) while Hegnauer (1973, as Saxifragaceae) gives some information on chemistry; see Schneider (2006) for a summary.

STRASBURGERIACEAE Solereder, nom. cons.   Back to Crossosomatales

Evergreen trees; chemistry?; stem with cortical bundles; nodes also 5:5; cuticle waxes as almost thread-like scales; leaf teeth with a single vein and opaque deciduous cap, stipules intrapetiolar, connate basally; flowers axillary; K 8-10, C 5 (6), A 10, in a single whorl, latrorse, connective thick, anthers attached their length, hypanthium 0, nectary on G, G [4-7], adnate to central column, 1 epitropous ovule/carpel, stigmas lobed; fruit rather dry, indehiscent, K persistent; outer testa of 5-12 layers of crystalliferous sclereids; endosperm moderate; n = 250.

1[list]/1: Strasburgeria calliantha. New Caledonia, on ultrabasic rocks. [Photo - Flower]

• Strasburgeriaceae are evergreen trees that may be recognised by their rather large, spiral and toothed leaves that have intrapetiolar stipules. The flowers are large and axillary and have spiral sepals, five petals and ten stamens with long anthers attached their lengths to the thick connective. The stoutly-pointed fruit is indehiscent.

Tertiary pollen like that of Strasburgeria has been found from Australia, Tasmania, and New Zealand.

The vascular supply to the carpel walls is complex. The hilum is about the length of the seed.

As Amaral (1991) suggested, Strasburgeria is to be excluded from Ochnaceae, where it was often included - i.a. it lacks cristarque cells and has crassinucellate ovules.

See also Dickison (1981a, 2006) and Cameron (2001) for information, and Oginuma et al. (2006) for the remarkable chromosome count.