EXTANT SEED PLANTS/SPERMATOPHYTA

Plant woody, evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins rich in p-parahydroxyphenyl and guaiacyl units; true roots present, apex multicellular, xylem exarch, branching endogenous; arbuscular mycorrhizae +; shoot apical meristem multicellular, interface specific plasmodesmatal network; stem with ectophloic eustele, endodermis 0, xylem endarch, branching exogenous; 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; leaves with single trace from sympodium ["nodes 1:1"]; stomata ?; leaf vascular bundles collateral; leaves megaphyllous [determinancy evolved first, then ad/abaxial symmetry], spiral, simple, veins -5 mm/mm² [mean for all non-angiosperms 1.8]; axillary buds associated with at least some leaves[?]; prophylls [including bracteoles] two, lateral; plant heterosporous, sporangia eusporangiate, on sporophylls, sporophylls aggregated in indeterminate cones/strobili; true pollen [microspores, i.e. no distal pore for release of gametes] +, grains mono[ana]sulcate, exine and intine homogeneous; ovules unitegmic, crassinucellate, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development first endo- then exosporic, tube developing from distal end of grain, to ca 2 mm from receptive surface to egg, gametes two, with cell walls, with many flagellae; 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 [N/O//A/C and P//BE lines], mitochondrial nad1 intron 2 and coxIIi3 intron and trans-spliced introns 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 in ANITA grade?], lignins derived from sinapyl as well as coniferyl and p-coumaryl alcohols, containing syringyl units, S lignin [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; shoot apex 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 a sieve plate and cytoplasm with P-proteins, companion cells from same mother cell that gave rise to the sieve tube; nodes unilacunar [1:?]; stomata with ends of guard cells level with pore, paracytic, outer stomatal ledges producing vestibule; leaves with petiole and lamina [the latter formed from the primordial leaf apex], development of venation acropetal, 2ndary veins pinnate, fine venation reticulate, veins (1.7-)4.1(-5.7) mm/mm², endings free; most leaves with axillary buds; flowers perfect, polysymmetric, parts spiral [esp. the A], free, development in general centripetal, numbers unstable; P not sharply differentiated, outer members not enclosing the rest of the bud, smaller than inner members; A many, 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, walls developing by centripetal furrowing; pollen subspherical, binucleate at dispersal, trinucleate eventually, tectum continuous or microperforate, ektexine columellar, endexine thin, compact, lamellate only in the apertural regions; nectary 0; G free, several, ascidiate, with postgenital occlusion by secretion, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, dry [not secretory]; ovules few [?1]/carpel, marginal, anatropous, bitegmic, [outer integument often largely subdermal in origin, inner integument dermal], inner integument 2-3 cells thick, micropyle endostomal, parietal tissue 1-3 cell layers; megasporocyte single, megaspore lacking sporopollenin and cuticle, chalazal, female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; P deciduous in fruit; seed exotestal; pollen germinating in less than 3 hours, siphonogamy, tube elongated, growing at 80-600 µm/hour, with callose plugs and callose-based walls, penetrating between cells, penetration of ovules within ca 18 hours, distance to first ovule 1.1.-2.1 mm; tube moves between nucellar cells, double fertilisation +, endosperm diploid, cellular [micropylar and chalazal domains develop diffently, first division oblique, micropylar end initially with a single large cell, divisions uniseriate, chalazal cell smaller, divisions in several planes], copious, oily and/or proteinaceous, embryo cellular ab initio, minute; 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 + C/PHYB + E gene pairs.

Evolution. Possible apomorphies for flowering plants 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, there is considerable variation between families in particular for several of these characters, and also because details of relationships among gymnosperms will affect the level at which some of these characters are pegged. For example, if reticulate-perforate pollen is optimized to the next node on the tree (see Friis et al. 2009 for a discussion), it effectively makes the pollen morphology of the common ancestor of all angiosperms ambiguous... For other features such a a nucellus only one (Nymphaeales) to three cells thick above the embryo sac and a stylar canal lacking an epidermal layer, although plesiomorphous for basal grade angiosperms (Williams 2009), where on the tree a thicker nucellus and a stylar epidermal layer are acquired has not yet been indicated.

NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessels + [one position], elements with elongated scalariform perforation plates; axial parenchyma diffuse or diffuse-in-aggregates; tectum reticulate-perforate [here?]; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.

CROSSOSOMATALES [PICRAMNIALES [SAPINDALES [HUERTEALES [MALVALES + BRASSICALES]]]]: ?

CROSSOSOMATALES Reveal  Main Tree, Synapomorphies.

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

Phylogeny. See the Dilleniales and the Saxifragales pages for further discussion on the relationships of Crossosomatales.

Evolution. Wikström et al. (2001) date the origin of stem Crossosomatales to (95-)91(-87) million years before present, diversification beginning (62-)56(-50) million years before present. The age of crown group Crossosomatales was estimated as (94-)88(-82) and (57-)51(-45) million years (two penalized likelihood dates), the stem group age being (112-)105(-98) and (88-)81(-74) million years; Bayesian relaxed clock estimates were up to 100 million years for the crown group, but were otherwise in the upper ranges of the figures just given (Wang et al. 2009), while Magallón and Castillo (2009) estimated ages of ca 106.4 and 106.8 million years (relaxed and constrained penalized likelihood datings) for stem Crossosomatales, and ages of ca 76.3 million years (both relaxed and constrained estimates again) for the crown group.

Oh (2009) discussed the complex biogeography of the group.

Chemistry, Morphology, etc. 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).

For a survey of wood anatomy, with a listing of the features - possibly plesiomorphic - common to the whole order, see Carlquist (2007c). 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. The inner integument in particular may be only three cells thick (Crossosoma, Geissoloma).

Phylogeny. 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 separately; see also Savolainen et al. (2000a). The tree is based on these studies, and also those of Sosa and Chase (2003), Oh and Potter (2006), Soltis et al. (2007a) and Oh (2009: Aphloiaceae not included). Some relationships within the group remain unclear and Crossosomatales as a whole are usually not very strongly supported - although with 1.0 p.p. in Soltis et al. (2007a). Recently the distinctive Guametala has been added to Crossosomatales (Oh & Potter 2006: three genes); it has strong support as sister to [Stachyuraceae + Crossosomataceae], although the position of Stachyuraceae was not stable in the analyses of Oh (2009). All in all, 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.

Classification. Does Gumillea (ex Cunoniaceae) belong here? It has no characters suggesting a particular position anywhere...

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

Synonymy: Geissolomatales Reveal, Staphyleales Lindley - Crossosmatanae Doweld

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

Evolution. 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, stamens = and opposite sepals, 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, or dry inflated and indehiscent, or follicle, K persistent or not; seeds few, hilum with 3-several scars of vascular strands in a horseshoe (not), testa multiplicative (vascularised), exotesta palisade (spongy - "Euscaphis"), 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; Tiffney 1979). [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.

Evolution. The family has an extensive fossil record in the northern hemisphere from the Eocene onwards (Tiffney 1979 for a review).

Chemistry, Morphology, etc. 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).

See Hegnauer (1973, 1990: chemistry), Carlquist and Hoekman (1985: wood anatomy), Dickison (1986: floral morphology, 1987a: pollen morphology, 1987b: vegetative anatomy), Ramp (1987: gynoecium), Tiffney (1979: seed structure), Danilova (1996: seed structure), and Simmons (2006: general).

Taxonomy. The limits of the genera accepted until recently, based on fruit morphology, have turned out to be unsatisfactory (Simmons & Panero 2000); see Simmons (2006) for genera now recognized.

Previous Relationships. 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 spirally-arranged leaves (see Dickison 1987 for a convenient table of differences), and molecular data suggest that they are not at all closely related. Here they are included in Huerteales.

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.

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

Previous Relationships. 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.

Evolution. 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 sepals, placentation intrusive apical-parietal, many biseriate ovules/carpel, style +, short, compitum down style; ovules with several-celled archesporium, obturator +; 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.

Chemistry, Morphology, etc. 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 described 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). Massive nucellus.

Details of the flower are taken from Hooker (1882) and of embryology from Mauritzon (1936b), 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.

Previous Relationships. Stachyuraceae were included in Theales by Takhtajan (1997).

CROSSOSOMATACEAE Engler, nom. cons.   Back to Crossosomatales

Deciduous shrubs; inulin, ellagic acid +; vessel elements with simple perforation plates; 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 sepals 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.

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

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).

Previous Relationships. Crossosomataceae were included in Rosales by Cronquist (1981) and were sister taxon to Geraniaceae in some early molecular studies (e.g. Price & Palmer 1993); Takhtajan (1997) included a monofamilial Crossosomatales in his Rosidae.

Aphloiaceae [Geissolomataceae + Strasburgeriaceae]: conspicuous protrusions from pollen apertures.

APHLOIACEAE Takhtajan   Back to Crossosomatales

Evergreen shrubs or trees; cork pericyclic; tracheids dimorphic; rays of two different widths; vasicentric or apotracheal parenchyma, stomata anisocytic; petiole bundles arcuate; plant glabrous; leaves two-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.

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

Details of the seed coat are in part taken from Takhtajan (1992), for wood anatomy, see Miller (1975), while Hegnauer (1989, as Flacourtiaceae) gives a few details of plant chemistry; see Kubitzki (2006b) for a summary.

Previous Relationships. Aphloia used to be included in Flacourtiaceae, although different anatomically (Miller 1975); it was included as a separate family in Violales by Takhtajan (1997).

Geissolomataceae + 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, terminated by persistent style; hilum on seed large.

GEISSOLOMATACEAE Endlicher, nom. cons.   Back to Crossosomatales

Evergreen shrubs; plants Al-accumulators; cork cambium 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]; ovule 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).

Chemistry, Morphology, etc. 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).

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

STRASBURGERIACEAE Solereder, nom. cons.   Back to Crossosomatales

Evergreen trees; 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 ³3mm long, ovules sessile, epitropous, style long, hollow; hilum much elongated; x = 25.

2/2. New Caledonia and New Zealand.

Ixerba Cunningham

Non-hydrolysable tannins 0; cork?; pits vestured; petiole bundles arcuate; stipules 0; inflorescence terminal, umbellate; stamens = and opposite sepals, pollen 4-5-colporate, disc lobed opposite petals; 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", exotestal and adjacent cells thickened; endosperm development?, cotyledons large; n = 25.

1/1: Ixerba brexioides. North Island, New Zealand.

Strasburgeria

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 (map: fossil localities (green) from Jarzen & Pocknall 1993). [Photo - Flower]

• Ixerba is an evergreen tree 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 conspicuous red arils. Strasburgeria is also an evergreen tree that may be recognised by its 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.

Evolution. Tertiary pollen like that of Strasburgeria, although rather smaller, has been found from Australia, Tasmania, and New Zealand (see Blufopollis scabratus: Jarzen & Pocknall 1993).

Chemistry, Morphology, etc. In Strasburgeria the vascular supply to the carpel walls is complex. The hilum is about the length of the seed. In Ixerba glands like those of leaf margin are in a cauline stipular position in seedlings. The vascular bundles in the receptacle are clustered.

Details of anatomy of Ixerba 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. For Strasburgeria, see also Dickison (1981a, 2006) and Cameron (2001) for information, and Oginuma et al. (2006) for the remarkable chromosome count. For general information, see Cameron (2003).

Previous Relationships. 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. Ixerba was placed in Grossulariaceae by Cronquist (1981), in Brexiaceae (now in Celastraceae) by Airy Shaw (1966: note the specific epithet), and as a family in Rosidae-Brexiales by Takhtajan (1997).

Synonmy: Ixerbaceae Doweld & Reveal