LIGNOPHYTA

True roots +; lateral meristems: cork cambium producing cork abaxially, vascular cambium producing phloem abaxially and xylem adaxially.

EXTANT SEED PLANTS/SPERMATOPHYTA

Plant woody, evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins derived from (some) sinapyl and particularly coniferyl alcohols, thus containing p-hydroxyphenyl and guaiacyl lignin units, (lignins derived from p-coumaryl alcohol, i.e. S [syringyl] lignin units); true roots present, apex multicellular, xylem exarch, and 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 and rays alone, tracheid/tracheid pits circular, bordered; mature sieve tube/cell lacking functioning nucleus, plastids with starch grains; phloem fibres +; 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, lamina with vein density up to 5 mm/mm² [mean for all non-angiosperms 1.8]; axillary buds associated with at most 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, developing after pollination, 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 duplications [three - [BP [A/N + C/O]] - copies], nrDNA with 5.8S and 5S rDNA in separate clusters; mitochondrial nad1 intron 2 and coxIIi3 intron and trans-spliced introns present.

MAGNOLIOPHYTA

Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, [cyanogenesis in ANITA grade?], S [syringyl] lignin units common, positive Maüle reaction [syringyl:guaiacyl ratio more than 2-2.5:1], and hemicelluloses as xyloglucans; root apical meristem intermediate-open; root vascular tissue oligarch [di- to pentarch], lateral roots arise opposite or immediately to the side of [when diarch] xylem poles; origin of epidermis with no clear pattern [probably from inner layer of root cap], trichoblasts [differentiated root hair-forming cells] 0; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, with gelatinous fibres; 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 cells from same mother cell that gave rise to the sieve tube; sugar transport in phloem passive; nodes unilacunar [1:?]; stomata with ends of guard cells level with pore, paracytic, outer stomatal ledges producing vestibule; leaves petiolate, lamina [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/all leaves with axillary buds; flowers perfect, pedicellate, polysymmetric, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P not sharply differentiated, with a single trace, outer members not enclosing the rest of the bud, often smaller than inner members; A many, filament not sharply distinguished from anther, stout, broad, with a single trace, anther introrse, tetrasporangiate, sporangia in two groups of two [dithecal], ± embedded in the filament, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally 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, 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, micropyle endostomal, outer integument 2-3 cells across, often largely subdermal in origin, inner integument 2-3 cells across, often dermal in origin, parietal tissue 1-3 cells across [crassinucellate], nucellar cap?; megasporocyte single, hypodermal, megaspore tetrad linear, functional megaspore chalazal, lacking sporopollenin and cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; P deciduous in fruit; seed exotestal; pollen binucleate at dispersal, trinucleate eventually, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing at 80-600 µm/hour, with pectic outer wall, callose inner wall and callose plugs, growing between cells, penetration of ovules via micropyle [porogamous] 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, 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]].

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. This is because some taxa basal to the [magnoliid + monocot + eudicot] group have been surprisingly little studied, there is considerable homoplasy as well as variation within and between families of the ANITA grade 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 as details of sugar transport in the phloem, their placement on the tree is frankly speculative. Finally, for features such as parietal tissue/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), I am unsure where on the tree a thicker nucellus and a stylar epidermal layer are acquired.

NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessels +, elements with elongated scalariform perforation plates; wood fibres +; 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.

CELASTRALES [OXALIDALES + MALPIGHIALES] (the COM clade): seed exotegmic, cells fibrous.   Back to Main Tree

Evolution. Divergence & Distribution. The age of this crown group was estimated as (108-)104(-100) or (95-)91(-87) million years (two penalized likelihood dates); Bayesian relaxed clock estimates were slightly older, to 108 million years respectively (Wang et al. 2009). Wikström et al. (2001) suggested a crown group age of some (92-)89(-86) million years, while Magallón and Castillo (2009) estimated ages of ca 101.9 and 102.2 million years for relaxed and constrained penalized likelihood datings for the divergence of the crown group.

Endress (2011a) suggested that a key innovation around here might be incompletely tenuinucellate ovules.

Chemistry, Morphology, etc. Endress and Matthews (2006a) suggest that an inner integument that is thicker than the outer is common in the COM clade, although this appears not to be the case for Celastrales; this character is not optimised to this part of the tree - but see within each order. Endress and Matthews (2006a) also note that members of the COM clade commonly have a relatively thin nucellus and arillate seeds. A number of Malpighiales, including Linaceae, have a fibrous exotegmen similar to that of Oxalidales. In Celastrales, see the similar exotegmen of Lepidobotryaceae, but not Celastraceae, given the recent departure of Perrottetia to Huerteales and Bhesa - to Malpighiales (Zhang & Simmons 2006).

Phylogeny. This clade of three orders is often retrieved (e.g. P. Soltis et al. 1999: weak support), Zhang and Simmons (2006), Zhu et al. (2007: mitochondrial matR gene, but appreciable support only when chloroplast genes added), Qiu et al. (2010), etc. Oxalidales (it is probably best to include Huaceae there) have been found to be sister to the other two orders in some analyses (e.g. Zhu et al. 2007, but support very weak), but here support weakened when chloroplast genes were added (see also Soltis et al. 2007a). Relationships are unclear in Moore et al. (2011).

Similarity in seed coat anatomy had suggested relationships between families now placed in Malpighiales and Oxalidales (and also Zygophyllales) to authors like Corner (1976), Dahlgren (1991) and Boesewinkel (1994).

CELASTRALES Link   Main Tree, Synapomorphies.

Vessel elements with simple perforation plates; tension wood 0 [2 genera of Celastraceae]; mucilage cells; stomata ?; lamina teeth?, stipules +; inflorescence cymose; flowers small; micropyle bistomal; chloroplast infA gene present. - 3(4) families, 94 genera, 1355 species.

Evolution. Divergence & Distribution. The age of crown group Celastrales was estimated as (87-)81(-75) or( 62-)56(-50) million years (two penalized likelihood dates), the stem group age being (108-)104(-100) and (95-)91(-87) million years; Bayesian relaxed clock estimates were slightly older, to 100 and 112 million years respectively (Wang et al. 2009). Wikström et al. (2001) suggested an age for stem Celastrales of some (92-)89(-86) million years, and a crown group age of some (88-)85(-82) million years before present, while Magallón and Castillo (2009) estimated ages of ca 71.6 and 71.7 million years for relaxed and constrained penalized likelihood datings for the divergence of crown Celastrales, 98.6 and 98.9 million years (relaxed and constrained estimates again) for stem Celastrales (Celastrales are sister to Malpighiales).

Chemistry, Morphology, etc. For possible additional synapomorphies of this clade, see Matthews and Endress (2005b, 2006). For instance, there is distinctive postgenital carpel closure by conspicuously elongated cells, and functionally imperfect flowers are common. All Celastrales are basically synascidiate and have quincuncial calyx aestivation.

Phylogeny. Huaceae were placed in this area by Nandi et al. (1998), and as sister to rest of Celastrales (inc. Lepidobotryaceae, when in the analysis), but with only moderate support, by Savolainen et al. (2000a, b); they were, however, not obviously close at all in Simmons et al. (2001 - Lepidobotryaceae not included) and were placed sister to Oxalidales with moderate support in Zhang and Simmons (2006; see also Soltis et al. 2011, etc.).

Includes Celastraceae, Lepidobotryaceae.

Synonymy: Brexiales Lindley, Hippocrateales Berchtold & J. Presl, Parnassiales J. Presl, Stackhousiales Martius

LEPIDOBOTRYACEAE J. Léonard, nom. cons.   Back to Celastrales

Tree; cork?; wood fluoresces; nodes also 2:2 [Lepidobotrys]; cristarque cells in bundle sheath; stomata paracytic; leaves two-ranked, lamina articulated with petiole, margins entire, stipel single, long (stipules adnate to petiole); plant dioecious, inflorescences terminal, congested; K and C similar in size; A 10, of two lengths, ± connate basally, anthers basifixed; nectary on inside of staminal tube; G [2-3], styles ± separate, stigmas capitate or style short, stigma lobed; ovules 2/carpel, collateral, apical, pachychalazal, epitropous, outer integument 7-10 cells across, inner integument ca 4 cells across [Ruptiliocarpon], parietal tissue ca 10 cells across, funicular obturator +; fruit a septicidal capsule, endocarp distinct, columella persisting; seed arillate, integuments multiplicative, (exotegmen not fibrous - Lepidobotrys); endosperm 0; n = ?

2[list]/2-3. West Africa (Lepidobotrys staudtii), Central and South America, scattered, to Peru (Ruptiliocarpon caracolito) (map: from Hammel & Zamora 1993; Heywood 2007). [Photo - Fruit]

• Lepidobotryaceae may be recognised by their entire, simple but articulated leaves with both stipules and stipels. The inflorescence often seems to be opposite the leaves because it is evicted by the growth of a robust axillary shoot. The flowers are small, with free sepals and petals and ten basally-connate stamens; the antepetalous stamens have longer filaments than the antesepalous whorl. The mesocarp, with its distinctive ladder-like fibres arranged radially, separates from the horny endocarp.

Chemistry, Morphology, etc. Ruptiliocarpon, at least, has distinctive spirotriterpenoids unique to flowering plants (Asim et al. 2010). There is no evidence other than morphology (articulation, stipels) that the apparently simply leaves are really unifoliate, and are derived from compound leaves. Dahlgren (1988) suggested that the vessel elements have scalariform perforation plates, but they are simple; scalariform pitting is found between vessels and rays. The pits of Ruptiliocarpon are vestured (Mennega 1993).

For information, see Link (1991a: nectaries of Lepidobotrys), Hammel and Zamora (1993: general), Tobe and Hammel (1993: flower and fruit of Ruptiliocarpon), Matthews and Endress (2005b: floral morphology), and Kubitzki (2004b: general), for nodal anatomy of Lepidobotrys, pers. comm. R. A. Howard.

Previous Relationships. Hutchinson (1973) also included Sarcotheca and Dapania (here in Oxalidaceae) with Lepidobotrys, and the leaves of Lepidobotrys are indeed superficially like those of Oxalidaceae, although differing in the stipel and paired stipules. However, the funicular obturator, septicidal capsule, etc., separates Lepidobotrys from Oxalidaceae; furthermore, the sieve tube plastids of Lepidobotrys are the common starch type. Cronquist (1981) included Lepidobotrys in Oxalidaceae, and Takhtajan (1997) placed Leipodoboryaceae and Oxalidaceae alone in his Oxalidales, while suggesting that Ruptiliocarpon - then quite recently described - was rather different, and might even be meliaceous.

CELASTRACEAE R. Brown, nom. cons.   Back to Celastrales

Shrubs and trees to lianes (herbs); hexitol dulcitol, flavonols +, ellagic acid 0; nodes 1:1; lamina with veins running to congested deciduous tooth; K with a single trace, in bud small, C enveloping flower bud, (fringed); stamens = and opposite K, (staminodes ± fringed); pollen often trinucleate; G opposite petals, stigma commissural; ovules with parietal tissue 0-1 cell across, laterlly thin; exotegmen?.

92[list]/1350: Maytenus (200, inc. Gymnosporia - 70), Salacia (150), Hippocratea (120, inc. Loesenerielle), Euonymus (130), Cassine (60), Crossopetalum (50), Parnassia (50). Largely tropical, but also temperate (map: from Heywood 1978; Hultén & Fries 1986). [Photo - Fruit, Fruit, Collection]

Parnassia et al.

Herbs; cork?; young stem with separate bundles; petiole bundle arcuate to ± circular; epidermis with tanniniferous cells; leaves spiral, lamina with 2ndary veins (sub)palmate, stipules 0; inflorescence monochasial or flowers single; K basally connate, quincuncial, C 0, 5; staminodes +, often complex and fringed, opposite petals; nectar at or towards base of staminodes; G [3-4(5)], to ± inferior, odd member abaxial, placentation parietal, stigmas dry, commissural; ovules many/carpel, uni- or bitegmic, outer integument 2-3 cells across, inner integument 3-4 cells across, nucellar cap 0?; fruit a capsule; seeds small, exotesta with thickened anticlinal walls, exotegmic cells with ± U-shaped thickening [Parnassia], raphe 0, or endotestal cell walls much thickened [Lepuropetalon], tegmen multiplicative, structure?; endosperm ± 0; n = 8, 9, 23 [Lepuropetalon].

2[list]/51: Parnassia (50). N. temperate to Arctic, Lepuropetalon spathulatum, S.E. U.S.A to Mexico, Chile (map: from Hultén 1971). [Photo - Parnassia Flower © H. Wilson]

• Parnassia and Lepuropetalum are herbs that may be recognised by their serrate leaves that often have reddish lines or dots when dry. The flowers are radially symmetrical, petals, when present, are free, there are only five stamens, and the ovary has parietal placentation. There are five staminodes, those of Parnassia being large and particularly distinctive.

The single, usually rather large flower of Parnassia is the first flower of a much reduced cyme, and the sessile bract has been interpreted as a petiolate bract the petiole of which is concaulescent with the pedicel (Watari 1939). Staminodes develop later than the stamens, but the androecium is obdiplostemonous. The stamens change their position as they mature, but are initially introrse (Hultgård 1987). The floral anatomy of Parnassia differs from that of Saxifragaceae (Bensel & Palser 1975), where the genus has often been placed. There are conflicting reports on testa anatomy. Lepuropetalon is a very small plant that lacks a corolla and has simple staminodes alternating with the sepals, the ovary is more or less inferior and the ovules are unitegmic.

See also information in Bohm et al. (1986: chemistry), Murbeck (1918: Lepuropetalon), Spongberg (1972: general), Leins (2000: floral morphology of Parnassia), Simmons (2004), and Wu et al. (2005: pollen).

Synonymy: Parnassiaceae Martynov, nom. cons., Lepuropetalaceae Nakai

The Rest

Shrubs and trees to lianes (herbs); gutta, pyrrolizidine and sesquiterpene alkaloids, distinctive triterpenoids [quinonemethides], (maytansinoids - synthesised by associated microorganisms), myricetin +; (cork cortical); true tracheids +; young stem with vascular cylinder; (nodes 3:3 - Brexia; 1:5-7 - Lophopetalum); latex sacs or laticifers +; petiole anatomy often complex; cuticle waxes 0 (platelets); stomata laterocytic (paracytic, etc.), epidermal cork-warts [some Celastroideae]; branching from previous innovation; leaves spiral, opposite, or two-ranked, lamina ptxyis involute (flat-conduplicate), (margins entire; spiny), colleters +, stipules often small (fringed [inc. Brexia]; 0); (2-)4-5-merous; K free or ± connate; A (2-)3-5(-many - Plagiopteron), extrorse, introrse or transverse, (anther slits confluent), (staminodes +, fringed, e.g. Brexia), tapetal cells often multinucleate (binucleate - Stackhousia); nectray disciform, massive, inside or outside A (0); pollen with endexinal fold in aperture (0); G [2-5(-several)], ± immersed in disc (inferior - A alone on top), when 3 odd member adaxial, style hollow, (long), stigma not or little expanded; ovules (1-)2-many/carpel, pleurotropous or apotropous (epitropous), apical to basal, (micropyle endostomal), outer integument 3-8 cells across, inner integument 2-4 cells across, (endothelium +), postament +; antipodal cells ephemeral; fruit a (septicidal) capsule, drupe, berry or schizocarp; seeds winged, or with exostomal, hilar or funicular arils; testa multiplicative, to 16 layers thick (vascularized), exotesta with thick cuticle (tanniniferous), mesotesta with sclerotic cells (0), (exotegmen of tall lignified fibres - Zinowiewia; fibres 0; endotegmen persistent, tanniniferous); endosperm copious to 0, embryo green, cotyledons (very) large, (connate); n = 8-10, 12, 14-16, 20, etc.

Synonymy: Brexiaceae Loudon, Canotiaceae Airy Shaw, Chingithamnaceae Handel-Mazzetti, Euonymaceae Berchtold & J. Presl, Hippocrateaceae Jussieu, nom. cons., Plagiopteraceae Airy Shaw, Pottingeriaceae Takhtajan, Salaciaceae Rafinesque, Siphonodontaceae Gagnepain & Tardieu-Blot, nom. cons., Stackhousiaceae R. Brown, nom. cons..

• The family is vegetatively variable - Microtropis may have oppposite, entire, exstipulate leaves, while spiral and opposite leaves on the one plant are not infrequent, as in Catha and Salacia. However, opposite, serrate leaves are common, the stipule-like structures are small and quite often fringed but the nodes are unilacunar; strongly ascending veins are prominent on dried specimens. Thin, spiral threads (vessels) are often evident when the lamina is torn transversely, as in Cornaceae. The inflorescences are often cymose, and the flowers, with their usually very broad disc in which the ovary is more or less immersed and five or fewer stamens, are often distinctive. The fruit varies greatly, but it is frequently a loculicidal capsule with winged or arillate seeds. The colleters may turn black, as in Paxistima.

Evolution. Divergence & Distribution. Both Salacioideae and Hippocrateoideae may be Old World in origin (Simmons et al. 2009a, b).

Ecology & Physiology. Celastraceae are ecologically one of the more important groups of lianes in the New World (Gentry 1991, as Hippocrateaceae).

Seeds of Parnassia are notably small when compared with those of their immediate relatives, possibly associated with the adoption of the herbaceous habit by the genus (Moles et al. 20005a).

Bacterial/Fungal Associations. Some South African Celastraceae have distinctive maytansinoids, ansamycin antibiotics, with a nineteen-member ring (18 C, 1 N), that is likely to be synthesized by the actinomycete Actinosynnema pretiosum, not the plant itself (Pullen et al. 2003; Cassady et al. 2004; Wink 2008).

Chemistry, Morphology, etc. The chemistry of the group would repay further study. Celastraceae commonly have yellow triterpene derivatives in their bark. Distinctive triterpenoid quinone methides are quite common in Celastraceae, although they have not been reported from Parnassioideae or from ex-Stackhousiaceae (Gunatilaka 1996). Monoamine alkaloids such as cathinone and cathine are potentially quite widely distributed in Celastreae (Simmons et al. 2008) and are the active principal in khat, the leaves of Catha edulis.

Both Brexia and Parnassia have leaf traces departing from the center of the stem well below the leaf they innervate (Cutler & Gregory 1998).

Potential floral synapomorphies for Celastraceae as presently circumscribed are calcium oxalate druses in floral tissues and ovary characters (Matthews & Endress 2005b; Zhang & Simmons 2006). Polycardia has epiphyllous inflorescences. Savinov (2008) drew the flowers of Stackhousia and Parnassia with the median sepal abaxial. Ex Stackhousiaceae appear to have polysymmetric flowers, but because two stamens are shorter than the others, there is a measure of monosymmetry, too, although I suspect that this is immaterial to its pollinators. A number of taxa have anthers that fall off soon after pollen is dispersed. Filaments in Celastraceae, at least, are often massive, and may not be articulated with the anther. The flower of Empleuridium has an ovary immersed in the disc and is described as being inferior; it is superior in fruit. Its ovule also has an endostomal micropyle. The inner integument may be thicker than the outer. Variation in fruit and aril is extensive (Simmons et al. 2001). Salacia has porate pollen; Tripterygium has epitropous ovules. Polyembryony is common in Celastraceae, the embryos developing from the inner integument.

Matthews and Endress (2005b) provide a great deal of information, especially about floral morphology, for this clade. For further details about morphology, see Pierre (1894: general); see also Andersson (1931), Mauritzon (1933, 1936c, 1939a), Copeland (1967) and Sharma (1968b), all embryology, Klopfer (1973: some floral morphology), Johnston (1975: Canotia), Stant (1952: anatomy of Stackhousia), Lobreau-Callen (1977: pollen), den Hartog and Baas (1978: stomata), Li and Zhang (1990), Tobe and Raven (1993), Takhtajan (2000), Savinov (2004) and Leins and Erbar (2010), both floral morphology, Simmons (2004: general) and Joffily et al. 92010: epidermal cork-warts). For general information on Pottingeria, see Airy Shaw et al. (1973), for testa anatomy, see Takhtajan (2000).

Phylogeny. Celastraceae have turned out to be a somewhat problematic group. Some of the difficulties encountered in elucidating the phylogeny of the family were because the it was polyphyletic. Thus Bhesa was distinctive in early morphological analyses (Simmons & Hedin 1999), and is now known to be a member of Malpighiales (Zhang & Simmons 2006) as is Goupia (Goupiaceae). Matthews & Endress 2005b found that Perrottetia was rather unlike other members of the family in characters of floral anatomy, however, the genus has found a firm home in Huerteales near Tapiscia (e.g. M. Simmons in Matthews & Endress 2005b; Worberg et al. 2009). Interestingly, the inclusion of these three genera (and also Siphonodon) in Celastraceae had previously been considered rather uncertain (Metcalfe & Chalk 1950; Ding Hou 1962; den Hartog & Baas 1978; Matthews & Endress 2005b); Siphonodon, however, does not seem about to move. Forsellesia has also moved, in this case to Crossosomataceae (Thorne and Scogin (1978). With the removal of these genera, vessels in Celastraceae are predominantly simple, nodal anatomy unilacunar, stipules are minute, indeed, the family became notably less variable morphologically (Zhang & Simmons 2006).

At the same time, as we will see, Celastraceae are accumulating taxa, that is, segregates are turning out to be firmly embedded in the family, and some of the mores distinctive groups are briefly characterized at the end of this section. For studies suggesting a broad circumscription of Celastraceae, see also Soltis and Soltis (1997), Savolainen et al. (1997), Zhang & Simmons 2006; etc. More particularly, Stackhousiaceae were included in Celastrales by Takhtajan (1997), but they are consistently embedded in Celastraceae in Savolainen et al. (2000a), Simmons et al. (2000, 2001a, b), Soltis et al. (2007a, but sampling), etc. Ex-Stackhousiaceae are sister to a poorly-supported clade including Maytenus (Coughenour et al. 2010).

Simmons et al. (2000) found Parnassia to group with Celastraceae such as Perrottetia, although with only moderate support. In Simmons et al. (2001a) Quetzalia and Zinowiewia were a clade sister to rest of Celastraceae s. l. (strong support), then Perrottetia (again!) and Mortonia were sister, in turn sister to rest of the family (poor support) using PHYB alone, but adding morpholology reversed the position of the two basal clades - Parnassia was not included. Zhang and Simmons (2006) could not resolve the relationships between Celastraceae and Parnassiaceae, the latter group being sister to Mortonia and Pottingeria, with parietal placentation, which formed a poorly supported clade very weakly associated with other Celastraceae, so they elected to keep them provisionally separate; Parnassia was monophyletic (100%) and sister to Lepuropetalum (see also Soltis et al. 2007a, 2011). Simmons et al. (2012), in a study focussing on Euonymeae, found that [Parnassia + Lepuropetalum]. [Mortonia + Pottingeria] and [Quetzalia + Microtropis] were sucessively sister to the rest, but support for these positions was not strong.

Other odd-balls. Brexia, another one-time segregate, appears to be sister to Empleuridium (Zhang & Simmmons 2006). i>Plagiopteron belongs here; see also Soltis et al. (2007a) who found it was embedded in the family, although sampling was poor. Simmons et al. (2009a) placed it in Hippocrateoideae, while Coughenour et al. (2010) found that it was sister to a clade including ex Salacioideae and Sarawakodendron. Pottingeria, of the monogeneric Pottingeriaceae, is probably also to be included; it is weakly supported as sister to Mortonia (Zhang & Simmons 2006). The xeromorphic Canotia, sometimes segregated in its own family, is close to Euonymus (Coughenour et al. 2010).

Within Celastraceae, Simmons et al. (2009a) and Coughenour et al. (2010) found that the arillate, capsular Sarawakodendron was sister to Salacioideae, the copious mucilaginous pulp of the berry of that group possibly also being arillate in nature. Sister to this combined group is Hippocrateoideae, with the arillate Helictonema being sister to other taxa (Simmons et al. 2009b; Coughenour et al. 2011). Many Hippocrateoideae have fruits that are deeply trilobed, the lobes being strongly dorsi-ventrally flattened, the seed wings are basal - although some taxa have a corky testa and the wing is vestigial, and the pollen apertures have an annulus (Coughenour et al. 2010, 2011). Sister to the clade made up of all taxa just mentioned is a largely Old-World clade that includes Lophopetaleae. Seed wings in Lophopetaleae vary in their position relative to the body of the seed. For relationships around Maytenus and Gymnosporia, see McKenna et al. (2011).

• Stackhousiaceae: Plant rhizomatous, ± herbaceous, sometimes even annual; flowers rather small and with a hypanthium lined by a nectary; sepals are small, petals clawed, the limbs being connate or not; A 3 + 2 shorter; G [2 (3-5)], 1 erect ovule/carpel, micropyle exostomal, style or styles +, stigmas elongate, commissural; fruit a dry schizocarp, (winged); exotesta with tangentially-elongated tanniniferous cells, tegmen absorbed; endosperm +; n = 9, 10, 15.

• Brexia: Plant with dulcitol; leaves conduplicate in bud; disc with stiff processes; ovules bistomal and crassinucellate; integuments multiplicative, exotestal cells tanniniferous, the outer wall thickened and with transverse thickenings in surface view, exotegmic cells laterally compressed. of the hour-glass type, other cells much thickened. Details of the anatomy of Brexia (Brexiaceae of some) may be found in Ramamonjiarisoa (1980), who notes its similarity to that of Celastraceae; for nodes, see Swamy (1964). Bensel and Palser (1975) suggested that the androecium in Brexiaceae is derived from an ancestor that was fasciculate; this is perhaps unlikely. Overall seed coat anatomy of Brexia and Celastraceae s. str. is similar; ovules are also similar (for the latter, see some details in Mauritzon 1933; also Hils 1985).

• Plagiopteron: Epidermal cells of the lamina crystalliferous; fibres thin-walled, unlignified, containing elastic material, as in some other Celastraceae (Takhtajan [1997] described the plant as having latex canals). The pollen has smooth exine, a collared ectopore and thickened endexine bordering the endopore - rather unlike other Celastraceae. Other features are also distinctive: indumentum stellate; stomata anomo- or cyclocytic; lamina margins entire, stipules minute; inflorescence axillary, paniculate; epicalyx (2-)4(-5), subulate; P (3) 4 (5), valvate, C 0, A numerous, filaments expanding apically and anthers opening by confluent apical slits, nectary 0?; G [3], 2 erect weakly crassinucellate apotropous ovules/carpel, micropyle zig-zag, endothelium +, style +, stigma punctate; fruit winged, septicidal; testa?. See Baas et al. (1979) for a discussion on the nature of the perianth in the genus, Tang (1994) for its embryology.

• Canotia: Leaves minute, distinctive axillary black-glandular patches; inflorescence fasciculate; 2-6 tenuinucellate ovules/carpel; fruit an initially septicidal capsule, then carpel units opening adaxially, or 1-seeded drupe; exotesta tanniniferous, thick-walled or not, exotegmen tracheoidal. Coughenour et al. (2010) suggest that the seeds have aril-derived basal wings (see also Catha).

• Nicobariodendron: Known only from the type. It has mucilage cells, distichous ("opposite" - Simmons 2004) exstipulate leaves, plant dioecious; inflorescence axillary, racemose; flowers small, staminate flowers with only two stamens borne outside the disc and a central pistillode; fruit a drupe, calyx persistent; seed single, basal (Vasudeva Rao & Chakrabarty 1985). Nicobariodendron is only doubtfully included here by Simmons (2004); I have seen no material and have no idea what it is.

• Pottingeria: Vessel elements with scalariform perforation plates [young stem]; leaves spiral, margins entire, 2ndary venation palmate, stipules minute, cauline; inflorescence fasciculate; flowers small, K and C free, borne near the outside and on undersurface of a large disc; G [3], placentation intrusive parietal, many ovules/carpel, style +, short, branches relatively long, spreading; fruit a septicidal capsule; A and placental bundles persistent; mesotesta fibrous; endosperm copious; n = ? No characters obviously link Pottingeria with any other group, although it is not obviously very different from Celastraceae. Indeed, Pottingeria was placed in Celastraceae subfamily Pottingerioideae by Airy Shaw (in Airy Shaw et al. 1973), and this is consistent both with nodal and testa anatomy.

Classification. For generic limits, see Islam et al. (2006), Simmons et al. (2008), and McKenna et al. (2011: the Maytenus and Gymnosporia areas); there are generic problems in Hippocrateoideae (Simmons et al. 2009b) and Salacioideae (Coughenour et al. 2010).

For an account of Stackhousioideae, see Barker (2012).

Previous Relationships. Plagiopteron was included in Flacourtiaceae by Sleumer (1961) and placed in Malvales by Takhtajan (1997). Brexia was included in Hydrangeaceae by Cronquist (1981), but was placed near Celastraceae by Takhtajan (1997). Stackhousiaceae were placed in in Celastrales by both Cronquist (1981) and Takhtajan (1997). Pottingeriaceae were included in Hydrangeales by Takhtajan (1997), who described the stamens as being adnate to the extrastaminal disc, but there is no evidence for such a position. Hippocrateaceae, with A often fewer than C, borne inside/on top of the disc, anthers usu. transversely dehiscent, aril 0, endosperm 0, have often been separated from Celastraceae, but are clearly embedded within them (see above).