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.

This clade is strongly supported, e.g. Chase et al. (1993), Soltis et al. (1997, 1999), Hoot et al. (1998), Nandi et al. (1998).

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].

ASTERIDS - Sympetalae redux?: Nicotinic acid metabolised to its arabinosides; (iridoids +); tension wood decidedly uncommon; C sympetalous, if evident only early in development, petals free, anthers dorsifixed?, (nectary gynoecial), ovules unitegmic, integument thick, endothelium +, nucellar epidermis does not persist, style +, long; seed exotestal; endosperm cellular, embryo long.

ERICALES + ASTERIDS 1 + 2: (C tube in flower), ovules tenuinucellate.

ASTERIDS 1 + 2: Ellagic acid 0, proanthocyanidins not common; inflorescence cymose; C forming a tube, A epipetalous, = and opposite K or P [polyandry (secondary) very uncommon indeed].

ASTERID I: G [2]; loss of introns 18-23 in d copy of RPB2 gene.

BORAGINACEAE + VAHLIACEAE + GENTIANALES + LAMIALES + SOLANALES: (8-ring deoxyflavonols +); vessel elements with simple perforations; C tube initiation late [sampling!], [vascularised] disc at base of G, style long.   Back to Main Tree

Vahlia is placed sister to Lamiales, but with only 63% bootstrap support by Albach et al. (2001b), or is associated more specifically with Boraginaceae in other analyses (Lundberg 2001e; B. Bremer et al. 2002).... Boraginaceae (plus Vahliaceae) may be associated with Lamiales; only in ndhF analyses is there some support for a position in Solanales (Olmstead et al. 1999, 2000; see also Savolainen et al. 2000a; Lundberg 2001e). In general, relationships between Gentianales, Lamiales and Solanales are unclear (Albach et al. 2001b; B. Bremer et al. 2002).

Boraginaceae have sometimes been associated with Lamiaceae (Lamiales) because both often have gynobasic styles and fruits with four separate nutlets, but the latter have iridoids, opposite leaves, square (not rounded) stems, monosymmetric flowers usually with 4 stamens, endosperm with haustoria and embryo with a long suspensor, and the two are not close. Furthermore, the radicle in Boraginaceae points upwards in fruit, while in Lamiaceae it faces downwards. No putative relative of Boraginaceae s. l. has alkannin or the carcinogenic pyrrolizidine alkaloids found in that clade. Oleaceae, Lamiaceae, and Solanaceae have (arabino)xyloglucans and some (galacto)xyloglucan hemicelluloses in the cell wall; the plesiomorphic condition for seed plants is to have (fuco(galacto))xyloglucans (O'Neill & York 2003; Harris 2005), but the sampling is very poor. Wu et al. (2006) suggest that the ancestral chromosome number of Solanales and Gentianales (specifically Solanaceae and Rubiaceae) was x = 11 or 12; no palaeopolyploidization seemed to have occured in this general area.

Unplaced:  Back to Main Tree

BORAGINACEAE Jussieu, nom. cons.

Isokestose and higher inulin oligosaccharides as storage; cork superficial to mid-cortical (pericyclic); (vessel elements with scalariform perforations); sieve tubes with nuclear non-dispersive protein bodies; nodes 1:1; petiole bundle(s) arcuate; plant often roughly hairy, hairs with a basal cystolith or cystolith-like body, and/or walls calcified; inflorescences terminal, cyme scorpioid, bracteoles 0; K free, C tube formation late, anther placentoid 0, 2 pendulous epitropous ovules/carpel, (heterostyly +), stigma dry; K persistent in fruit; micropylar and chalazal endosperm haustoria +.

148[list]/2740 - in six groups below. Temperate to tropical. [Photos - Collection]

1. Boraginoideae Arnott

Herbs (shrubs); pyrrolizidine alkaloids, alkannin, prenylated napthoquinones [roots with reddish or purple dye]; (pits vestured); one (or both) bracteoles 0; corolla often rotate, mouth with fornices [inpushings of corolla tube], anther connective produced or not, pollen trinucleate, (with pseudocolpi; 4- or more colporate), tube with callose, placental obturator +, (nucellar cap +), endothelium 0, style gynobasic, hollow, (styles + [divided]), stigma punctate to capitate; fruit a schizocarp (capsule - Wellstedia), with (1-)4 nutlets; (testa vascularised), exotestal cells with outer walls thickened and lignified (other patterns of thickening, or unthickened); endosperm oily or 0, also nuclear, endosperm 0, haustoria 0; n = (4-)12(-13).

112/1600: Onosma (150), Cryptantha (150: esp W. North and South America, some with basal, cleistogamous flowers and non-dispersing fruits - Grau 1983), Myosotis (90), Cynoglossum (75), Paracaryum (70), Plagiobothrys (70), Lithospermum (60: used in dyeing), Amsinckia (50), Mertensia (50), Trigonotis (50). Largely (warm) north temperate, some on mountains in the tropics (Map: see Meusel et al. 1978; Hultén & Fries 1986; Långström & Chase 2002; FloraBase 2005: incomplete).

The corolla often shows color changes on aging, pink to blue, yellow to pink to blue, yellow to white; p.H. changes of the cell sap are involved.

The "typical" borage! Trichodesmis has opposite leaves and the pendulous and campanulate flowers are borne in a congested inflorescence at the end of a rather long peduncle, Echium has obliquely monosymmetric flowers, while the flowers of some species of Nonea may be vertically monosymmetric, the abaxial stamen being much longer than the others. The corolla in Boraginaceae s.l. usu. has many veins diverging in the lobes, but not in Wellstedia. However, the position of Wellstedia - and Codon - must be confirmed; see immediately below for the morphology of the former, which in Moore and Jansen (2006) did unambiguously link with the other two Boraginoideae in the analysis. With pollen grains at ca 4.1 µm long, Cryptantha clevelandii has about the smallest grains of any flowering plant (Hargrove & Simpson 2003). Amsinckia has very strongly bilobed cotyledons.

Codon (Codonoideae Retief & A. E. van Wyk) has a bicarpellate gynoecium with many ovules; the fruits are loculicidal. Subshrubs; plant prickly-hairy; calyx, corolla and androecium are 10-12-merous, K deeply linear-lobed (Retief & van Wyk 2005; Retief et al. 2005). 1/2. S.W. Africa (Map: see Retief et al. 2005). The combination of a many-lobed corolla and a bicarpellate gynoecium is a little odd in the asterid I + II groups, but c.f. Dialypetalanthus (Rubiaceae).

See Y. Heslop-Harrison (1981) and Bigazzi and Selvi (2000) for the morphology of stigma papillae, Hilger (1985) for fruit development, Bigazzi and Selvi (1998) for pollen morphology of Boragineae, and Långström and Chase (2002) for tribal relationships.

Synonymy: Anchusaceae Vest, Buglossaceae Hoffmannsegg & Link, Cerinthaceae Martynov, Echiaceae Rafinesque, Onosmaceae Martynov, Wellstediaceae (Pilger) Novák (peltate glands +; flowers 4-merous, pollen with coarse-reticulate mesocolpium [cf. hydrophylloids], nectary 0, style terminal, bilobed, 1 pendulous ovule/carpel; fruits are capsules [the primary line of dehiscence is loculicidal; the septae may also separate from the walls]; endosperm 0, embryo curved, cotyledons accumbent. Wellstedioideae Pilger. The flowers are arranged in two serried ranks along the stem.)

Hydrophyllaceae + Heliotropioideae + Cordioideae + Ehretioideae + Lennooideae: (plant smells unpleasantly); endothelium +; single layer of transfer cells [cells with labyrinthine ingrowths of the wall] in the testa; micropylar (and chalazal) haustoria +.

2. Hydrophylloideae Burnett

Herbs (shrubs); tannins 0, inulin?, alkaloids?; leaves (opposite; compound), margins lobed, toothed (entire), 2ndary veins pinnate to palmate; cymes scorpioid, bracts and bracteoles usu. 0; (K free), A usu. with small scales at each side of the base, pollen also colpate, tubes with callose (0 [Phacelia]), disc usu. 0, G with parietal placentation, 2-many (crassinucellate; pleurotropous) ovules/carpel, styles +/0, stigma punctate; fruit a loculicidal (+ septicidal) capsule (indehiscent); seeds ruminate by inpushings of the exotestal cells or not, exotestal cells thickened on inner and radial walls, endotestal cells persistent, walls esp. the inner periclinal ± thickened; endosperm also nuclear, copious to scanty, (reserve hemicellulose), embryo (short), green or white; n = 5, 9-13, 19.

17[list]/225: Phacelia (150), Nama (45). New World, esp. drier areas W. United States. [Photo - Undetermined Flower]

There are acicular protein bodies in the nucleus of sieve elements. The mesocolpium is coarse-reticulate, as in some Boraginaceae s. str. (Wagenitz 1992). Di Fulvio (1989a) described the ovules of Nama as being crassinucellate.

Some information is taken from Wilson (1960).

Synonymy: Ellisiaceae Berchtold & J. S. Presl, Eutocaceae Horaninow, Hydrophyllaceae R. Brown, nom. cons., Sagoneaceae Martynov

Heliotropioideae + Cordioideae + Ehretioideae + Lennooideae: bark oxidises; pollen tubes lacking callose; transfer cells in funicle and placenta also; fruit with a multilayered endocarp.

3. Heliotropioideae Arnott

Trees or lianes to herbs; pyrrolizidine alkaloids +; cambium not storied; pericyclic sheath 0 [?always]; pits not vestured (+); petiole bundles arcuate; (tetrahedral crystals +); leaves usu. conduplicate [Tournefortia]; C imbricate or with involute margins, A connate at apex via papillae, connective not produced, weakly crassinucellate, nucellar cap +, obturator +, style + (0), stigma receptive only basi-laterally, discoid, then conical and ± bilobed at sterile apex, or hemispherical, with a ring of hairs, wet; fruit (drupe with 4, 1-seeded stones), schizocarp; seed exotestal; endosperm 0 at maturity, embryo curved or straight, cotyledons large, suspensor long; n = 5, 7-9, 11-14, etc.

5/405: Heliotropium (250), Tournefortia (150, salicylic acid: polyphyletic - see Diane et al. 2002a). Tropical to warm temperate (Map: see Gottschling et al. 2004; Flora Base 2005). [Photo - Flower]

Subtending leaves are sometimes displaced up the branches they subtend in Tournefortia; T. astrotricha lacks inulin! Generic limits need attention (Diane et al. 2002a; Hilger & Diane 2003); Craven (2005) suggests that the whole lot are best placed in Heliotropium.

Details of embryology are taken from DiFulvio (1978). The integument is about eight cells across.

Synonymy: Heliotropiaceae Schrader, nom. cons.

4. Cordioideae Link

Trees, shrubs or lianes; terpenoid-based quinones +; cambium storied; 2ndary phloem stratified; pits barely vestured; nodes 3:3 [Cordia, but see below]; petiole bundles (invaginated) annular and with (cortical and) rib bundles; crystal sand and prismatic or columnar crystals +; leaf margins toothed to entire; bracteoles usu. 0; K valvate to open, persistent to accrescent, C contorted (imbricate), anther connective usu. not produced, pollen often spiny, pseudocolpi 0, (3-porate - Varronia), ovules straight [atropous], tenuinucellate, nucellar cap [Cordia] +, styles + (divided), stigmas punctate to capitate; fruit often a drupe, stones 1 (2, 4) (K accrescent [an anthocarp!]); testa vascularised [Cordia], 3-4 layers of transfer cells; endosperm haustoria?, 0, cotyledons plicate, toothed; n = 9, 14-16, 19.

3/330: Cordia (200+: esp. West Indies, heterostylous), Varronia (100+). Tropical, especially South America (Map: see Gottschling et al. 2004; Flora Base 2005). [Photo - Flower] [Photo - Fruit]

The growth pattern of some species of Cordia, including the myrmecophilous species, is distinctive: the apex of the stem aborts, some branches are plagiotropic, another becomes orthtropic and forms the renewal shoot. The central foliar trace of Cordia is at least sometimes inverted C-shaped when it joins the central stele, but I do not know how widespread this character is (see Neubauer 1977 for nodal anatomy of Cordia myxa - modified 1:3). The inflorescence can be oddly placed.

For generic limits, see Gottschling et al. (2003: includes Coldenia [sister to rest of group] and Saccelium [in Cordia s. str.]), Gottschling et al. (2005: equivocation as to whether Coldenia should be included in their Cordiaceae - if it is, as here, the clade has few apomorphies) and Miller and Gottschling (segregation of Varronia, sister to Cordia - so not necessary, although supported by morphology). For pollen morphology, see Nowicke and Miller (1990).

Synonymy: Cordiaceae Dumortier, nom. cons., Sebestenaceae Ventenat

5. Ehretioideae Arnott

?Smell; trees or shrubs (herbs); inulins?; cambium storied; (pits vestured - Rochefortia); petiole bundle arcuate; leaf margins toothed (entire); bracteoles?, flowers (4-)5-merous; K (5-15), C imbricate or inwards-folded, connective usu. not produced, (pollen 3-porate), mesocolpium coarse-reticulate, placentation apical to axile, ovules (weakly) crassinucellate (1/carpel), styles ± well developed, stigmas capitate or elongate; K accrescent or not, fruit a drupe, stone (1-)2-(4-)seeded, or a schizocarp; endosperm copious to 0, embryo curved, suspensor long; n = 5, 7-11, 13, 16, etc.

8/170: Ehretia (75), Bourreria (50). Mostly tropical (Map: see Gottschling et al. 2004; Flora Base 2005).

Ehretioideae are heterogeneous in wood anatomy; both Antrophora and Lepidocordia have vessels in radial groups, apotracheal parenchyma, and fiber tracheids with bordered pits (Gottwald 1982). In embryology Ehretioideae are perhaps closest to Heliotropioideae (Diane et al. 2002a); a number of the former have a valvate calyx.

For genera, see Miller (2003), and for pollen, see J.-X. Liu et al. (2003).

Synonymy: Ehretiaceae Martius, nom. cons.

6. Lennooideae Craven

Echlorophyllous, herbaceous root parasites; chemistry?; cork?; sieve tubes with nuclear non-dispersive protein bodies?; stem with cortical bundles; nodes?; leaves spiral, reduced to scales; inflorescences congested, flowers 5-10-merous; K long, narrow, free, pollen tube callose?, nectary 0, G [5-16], placentation axile, loculi subdivided, ovule ?type, style stout, stigma capitate or lobed; fruit a drupe, irregularly schizocarpic (± circumscissile), K and C persistent; exotesta with fine reticulate thickening; endosperm starchy, ?development, ?haustoria, embryo minute, undifferentiated; n = 9.

3[list]/7. S.W. U.S.A. to N. South America (Map: from Brummitt 2007).

The embryology is largely unknown.

See The Parasitic Plant Collection for general information.

Synonymy: Lennoaceae Solms-Laubach, nom. cons.

• Rough to hispid, spiral, exstipulate leaves occur throughout the family, the inflorescence is cymose, and the flowers usually are radially symmetrical and with an often clearly 4-lobed and 4-ovulate bicarpellate gynoecium. Major groupings within Boraginaceae are easy enough to recognise.

• Boraginoideae are usually herbs that can be recognised by their often spiral leaves the hairs on which have distinctive white bases and their helicoid cymose inflorescences. The flowers lack one or both bracteoles and often have rotate corollas; the style is gynobasic, and the fruit has four nutlets which may be ornamented with various kinds of hooks and other projections.

• Heliotropioideae are often vegetatively like Boraginoideae and also have similar inflorescences and flowers, but the style is terminal and the stigmatic head is almost plug-like. The fruit is often a schizocarp. The stem may oxidise, the slash turning reddish.

• Cordioideae and Ehretioideae are both woody, and sterile members can be hard to assign to this area, although quite often the bark is fibrous, the stem is oxidising, and the twigs are whitish in color. Both subfamilies have cymose inflorescences, but the flowers of Cordioideae can often be recognised by their branched styles and capitate stigmas; the style in Ehretioideae is once-divided. The fruits are drupes, surrounded by a persistent and more or less accrescent calyx.

• Hydrophylloideae are mostly herbs, again often hispid and with helicoid cymes, but the corolla is more open than in Boraginoideae, the style is terminal, the placentation parietal, and the fruit is a capsule.

• Lennooideae are echlorophyllous root parasites with congested inflorescences; the flowers are rather boraginoid, although 5-10 merous.

The diversification of primarily woody taxa may have taken place in the mid-Cretaceous, some 90 million years ago, in South America (Gottschling et al. 2004); Wikström et al. (2001) estimate divergence of the clade 81-77 million years before present, i.e. rather later and some time in the Ypresian-Thanetian ([Vahliaceae + Lamiales] are the sister taxon), with Hydrophylloideae and Boraginoideae separating 59-56 million years before present. Moore and Jansen (2006) also suggest rather later dates, with very end Cretaceous 67-63 million years ago for diversification of the woody taxa. The latter discuss the diversification of the desert genus, Tiquilia, in some detail; it may have originated in the Paleocene ca 58 million years before present but began to diversify only rather later, some 33-38 million years before present.

Boraginaceae (including Hydrophylloideae) are not often eaten by caterpillars of butterflies (Ehrlich & Raven 1964). However, the wilting plants and/or the flowers of Boraginoideae and Heliotropoideae, especially the latter, are visted by adult butterflies and moths Ctenuchidae, Arctiidae, Danainae and Ithomiinae because the pyrrolizidine alkaloids they contain are used as the basis of the pheromones of these lepidoptera, or of compounds that other animals find distasteful (also Crotalaria and some Apocynaceae and Asteraceae-Asteroideae: Edgar et al. 1974; Ackery & Vane-Wright 1984 [considerable detail for the danaines]; Boppreé 1986; Brown 1987); Cordia (Cordioideae) is also sometimes visited, although it is not known to contain these alkaloids. Holm (1979) noted that some Boraginoideae and Hydrophylloideae have similar rusts.

Boraginoideae are sister to rest of the group, and may include Codon (10-12-merous, ex Hydrophyllaceae, but the only African member) and Wellstedia (also African) as clades successively sister to the remainder. Two groups of ex Hydrophyllaceae also are successive sister taxa within the other major clade in some reconstructions, hence loculicidal capsules may be plesiomorphic for the whole group, and Nameae in particular may be sister to the Cordioideae + Heliotropoideae + Ehretioideae (Olmstead & Ferguson 2001; Moore & Jansen 2006, low bootstrap but high posterior probabilty); they include the only woody and tropical members of Hydrophyllaceae s. str. (i.e., excluding Hydrolea, see below). However, Gottschling et al. (2001), looking at the secondary structure of the ITS1 transcript, found Hydrophyllaceae s. str. to be monophyletic (the position of Codon is uncertain) and sister to [Heliotropoideae [Cordioideae + Ehretioideae]] - in the tree above I follow this topology. Boraginaceae and Hydrophylloideae also have meroterpenoids, rusts (see above) and very variable endosperm development in common.

Floral evolution shows much of interest in this group, although without an comprehensive phylogeny details remain poorly known. Several taxa have flowers that are not the normal 5-merous core eudicot flower. These include Codon (10-12-merous, ex Hydrophyllaceae; the only African member), Hoplestigmataceae (these seem likely to end up around here) and Lennooideae. Boraginoideae are well known as a group with a gynobasic style, but the terminal style of Heliotropoideae is in fact likely to be derived from a gynobasic style, as is evident in the fact that the transmitting tissue proceeds to the base of the gynoecium (e.g. Hanf 1935). Finally, the evolutionary relationships of the several-seeded capsules of Hydrophylloideae to the fruits of the rest of the group are unclear.

Lennooideae are often associated with Boraginaceae and/or Hydrophyllaceae (Cronquist 1981; Takhtajan 1997; esp. Yatskievych et al. 1986), and rps2 data even suggest a position within Ehretioideae. Ehretia + Lennoaceae also have a shared intron in the mitochondrial gene cox1, and Tiquilia in particular is sister to Pholisma (Smith & dePamphilis 1998; Smith et al. 2000; Olmstead & Ferguson 2001). (Tiquilia and immediate relatives, mostly plants of American deserts, are unusual within Ehretioideae in being herbs, or shrubs that flower very quickly, and their inflorescences may be crowded. Their fruits are dry, and secondary veins in the leaves go to the sinuses [Richardson 1977]). Note that if this relationship is confirmed, members of the erstwhile Lennoaceae are parasitizing their close relatives! Until there is further resolution of phylogenetic relationships, I have retained Lennooideae as separate from Ehretioideae. For other relationships within Ehretioideae, see Gottschling and Hilger (2001).

All in all, it may be useful to recognize more than one family here, given appropriate support, or at least five subfamilies...

Pteleocarpa, with vestured pits, is usually included in Boraginaceae s.l., but it is here placed in Gelsemiaceae (Gentianales). Hydrolea, ex Hydrophyllaceae, but with axile placentation, is here to be found in Solanales. However, Hoplestigmataceae (see unplaced eudicots), from Africa, may well end up being associated with Boraginaceae.

The hydroxycinnamic acid depside, rosmarinic acid, is known from Boraginoideae and Hydrophylloideae (as well as some Lamiaceae!: Mølgaard & Ravn 1988). Taxa with root trichoblasts in radial files are quite common in Boraginaceae s.l. There is considerable variation in ovule and endosperm development, conveniently summarized by Khaleel (1985). A variety of septal structures are produced in this group (see Gottschling 2004). There is controversy as to whether the ovules in some Boraginaceae s.l. are crassinucellate or tenuinucellate. Given that ovules with even a single layer of parietal tissue are crassinucellate by the definition followed here, Boraginoideae, for example are tenuinucellate, while Ehretioideae and Heliotropoideae are crassinucellate, Hydrophyllaceae s. str. seem to show both conditions (e.g. Di Fulvio 1981, 1987; cf. Gottschling 2004). Suspensor size varies considerably in this group; I have not attempted to see if variation correlates with clades. The style in at least some Boraginoideae and Hydrophylloideae apears to be hollow (Guéguen 1901). There is variation in the presence of the mitochondrial coxII.i3 intron (two species sampled!).

For further information, see Gürke (1891: general), Svensson (1925: embryology), Khaleel (1977: testa anatomy), Prósperi and Cocucci (1979: callose, in Boraginoideae, variable in Hydrophyllaceae s. str.), Gottwald (1982), Fisher et al. (1989: sieve tubes with nuclear non-dispersive protein bodies), Heubl et al. (1990: esp. Cordia), Al-Shehbaz (1991: general), Thulin and Johansson (1996), Di Fulvio (1997: protein inclusions in nucleus), Förther (1998: esp. Heliotropioideae), Ferguson (1999: relationships), Olmstead and Ferguson (2001: relationships), Diane et al. (2002b: transfer cells), Buys and Hilger (2003: inflorescence morphology) and Gottschling et al. (2004: diversification). I am grateful to Mark Gottschling for discussion, and also the tree used here.

Synonymy: Boraginales Dumortier, Echiales Lindley - Boraginanae Doweld

VAHLIACEAE Dandy   Back to Unplaced

Herbs or subshrubs; iridoids +; nodes 1:1; petiole bundle arcuate; hairs uniseriate-glandular; leaves opposite; flowers small; K valvate, C free, G [2(-3)], inferior, disc +, 1-locular, placentae apical, many bitegmic ovules/placenta, outer integument ca 3 cells across, inner integument 2, but more at micropyle, micropyle endostomal, styles distinct, diverging, stigmas ± capitate; fruit a septicidal capsule, K persistent; exotestal cells ± elongated, outer wall or all walls thickened, endotesta a layer of cells with well-developed U-thickenings, neither lignified, raphe disappears; endosperm slight; n = 6, 9.

1[list]/8. Africa and Madagascar to India (Map: from Bridson 1974).

• Vahliaceae are densely glandular-pubescent herbs or subshrubs with opposite entire leaves and rather spreading basically cymose inflorescences bearing small flowers with inferior ovaries; they look rather like some Rubiaceae. However, there are no stipules, the relatively large, persistent calyx is valvate, the petals are free, and the gynoecium has a single loculus with apical placentae. The fruit dehisces at the apex inside the sepal lobes.

Although the ovary has only a single locule, dehiscence of the fruit occurs between the styles, and this is equivalent to dehiscence along the septal radii.

Vahliaceae were included in Saxifragales by Cronquist (1981) and Takhtajan (1997).

Some information is taken from Thouvenin (1890), Mauritzon (1933: ovule), and Cutler and Gregory (1998: anatomy); Bridson (1974) monographed the family.

Synonymy: Vahliales Doweld - Vahlianae Doweld

GENTIANALES + LAMIALES + SOLANALES: ?

GENTIANALES Lindley  Main Tree, Synapomorphies.

Iridoids [different pathways!], monoterpene indole alkaloids, (O-methylated) flavones and flavonols +, myricetin rare; glandular hairs 0; pits vestured; nodes?; petiole bundle(s) arcuate; branching from current flush; leaves opposite, joined by a line across the stem, (stipules +), colleters +; (corolla swollen at the apex in bud), pollen orbicules +, many ovules/carpel, endothelium 0; endosperm nuclear. - 5 families, 1118 genera, 16637 species.

Gentianales may be some 89-83 million years old (Wikström et al. 2001), but timing of diversification within the clade is unclear since Dialypetalanthus appears as sister to the rest of the clade - here it is included within Rubiaceae.

The monoterpene indole alkaloid camptothecin is scattered through this clade, e.g. it is in Opiorrhiza (Rubiaceae), Mostuea (Gelsemiaceae) and Ervatamia (Apocynaceae) (see Lorence & Nessler 2004). The colleters consist of secretory palisade surrounding an elongated axis, so they are "proper" emergences. However, in many Gentianaceae they have a simpler structure and are "true hairs". They are frequently borne on leaves, or even the calyx or corolla (Renobales et al. 2001), as well as in their normal axillary position. Tapetal variation is considerable, plasmodial tapeta being known from some species of Gentianaceae, Rubiaceae and Apocynaceae (Furness 2008). Most families have taxa with bi- or trinucleate pollen grains. There is substantial variation in the presence of the mitochondrial coxII.i3 intron in this clade.

The circumscription and relationships of Loganiaceae are a key to understanding the circumscription and relationships of Gentianales. Loganiaceae seemed to show relationships with many sympetalous groups, and Bentham (1856) compared a broadly circumscribed Loganiaceae to the less-wooded area from which obvious forests (representing more distinctive families such as Rubiaceae, Solanaceae, etc.), had been removed. Loganiaceae in this sense (e.g. Leeuwenberg 1980) had ca 22 genera and 310 species. However, Buddleja s.l. and Androya (not immediately related), Peltanthera and Sanango (not immediately related), Plocospermum, Nuxia and Retzia and Polypremum, all members of a broadly circumscribed Loganiaceae are in five separate clades in Lamiales (Scrophulariaceae, Gesneriaceae, Plocospermataceae, Stilbaceae and Tetrachondraceae respectively), while Desfontainia (Desfontainiaceae) is an asterid II (for references, see those families) - hence it is not surprising that Loganiaceae seemed to be such a "central" family.

Struwe et al. (1995) suggested that Loganiaceae, even when more narrowly circumscribed, were extremely paraphyletic, with clades including about 1,300 genera and 15,500 species (Rubiaceae, Gentianaceae, Apocynaceae + Asclepiadaceae) coming from within them; they delimited families accordingly. B. Bremer (1996a), Potgeiter et al. (2000) and Backlund et al. (2000) suggest rather different relationships - Rubiaceae are sister to Loganiaceae, Gentianaceae, Gelsemiaceae and Apocynaceae. Relationships between these last four are not clear. M. Endress et al. (1996) found the relationships Gelsemiaciaceae [[Strychnaceae + Geniostomaceae - well supported] Apocynaceae], see also B. Bremer and Struwe (1992). In other analyses, as in the tree below, there is weak support for a relationship between Gelsemiaceae and Apocynaceae (Backlund et al. 2000; Jiao & Li 2007: for the tree, see also B. Bremer 1999; Rova et al. 2002).

Some information is taken from Rogers (1986: general), Erbar and Leins (1996: corolla development), Conn et al. (1997: general), Jansen and Smets (1998: wood anatomy, 2000: vestured pits), and Vinckier and Smets (2002a, c: orbicules).

Includes Apocynaceae, Gelsemiaceae, Gentianaceae, Loganiaceae, Rubiaceae.

Synonymy: Apocynales Bromhead, Asclepiadales Dumortier, Cinchonales Lindley, Chironiales Grisebach, Galiales Bromhead, Loganiales Lindley, Rubiales Dumortier, Theligonales Nakai, Vincales Horaninow - Gentiananae Reveal - Asclepidopsida Brongniart, Coffeopsida Brongniart, Rubiopsida Bartling

RUBIACEAE Jussieu, nom. cons.   Back to Gentianales

Plant tanniniferous; (cork deep-seated); true tracheids +; nodes 1(-3 or more):1(-3 or more); crystal sand +/0; secretory sacs widespread; stomata paracytic; leaves usu. with flat ptyxis, stipules interpetiolar (sheathing; intrapetiolar; two pairs; toothed or not), innervated from circumferential vascular ring; flowers often aggregated, 4- or 5-merous (heterostyly +), K small, aestivation open (free; 0), C with early tube formation, (valvate), G inferior (largely superior in fruit), nectary on top, placentation axile (to parietal), (ovules crassinucellate), (styles ± well developed), wet or dry; fruit baccate, drupaceous or capsular, variously dehiscent; seeds 1-many, (pachychalazal; ruminate), exotesta alone persisting, papillate/short hairy or not, cells variously thickened (mesotestal cells thickened); endosperm cellular or nuclear, often hemicellulosic, embryo straight to curved, suspensor haustorium +; n = 11 (10-16).

660[list]/11,150 - in four groups below. World-wide, but especially tropical (Map: from Hultén 1958, 1971; Brummitt 2007). [Photo - Flower]

1. Rubioideae Verdcourt

Commonly herbs; shikimic-acid derived anthraquinones, plants Al accumulators [esp. in woody taxa]; (root with superficial cork cambium - Paederia); raphides + [square in transverse section]; hairs articulated; C valvate, heterostyly esp. common; loss of atpB promoter.

Psychotria s. str. (1400), Cephaelis (100: conspicuous inflorescence bracts), Myrmecodia, Hydnophytum (55: all part of Psychotria s.l.?, see Nepokroeff et al. 2000), Hedyotis (500: inc. Oldenlandia), Galium (400), Spermacoce (inc. Borreria: 275, see Dessein et al. 2005b for extensive pollen variation, Vaes et al. 2006 for development of the remarkable petals, pollination sometimes explosive), Palicourea (250), Argostema (100), Morinda (80), Gaertnera (70: see Malcomber 2002). Worldwide. [Photo - Fruit]

Opiorrhiza has the atpB promoter region that is lacking in all other Rubioideae (Manen & Natali 1996; Natali et al. 1996). Within Rubioideae, Rubieae are well supported as being monophyletic by both morphological and molecular data (Rogers 2005 for literature). For further information on the phylogeny of Rubioideae, see Andersson and Rova (1999), Backlund et al. (2007), Kårehed and Bremer (2007: Knoxieae), and Smedmark (2008: Urophylleae).

Synonymy: Aparinaceae Adanson, Asperulaceae Spenner, Cynocrambaceae Endlicher, Galiaceae Lindley, Hedyotidaceae Dumortier, Houstoniaceae Rafinesque, Hydrophylacaceae Martynov, Lippayaceae Meisner, Lygodisodeaceae Bartling, Nonateliaceae Martynov, Operculariaceae Perleb, Pagamaeaceae Martynov, Psychotriaceae F. Rudolphi, Theligonaceae Dumortier, nom. cons. (iridoids +, raphide sacs +; plant monoecious, plant anemophilous, staminate flowers paired, opposite, not subtended by leaves; P tubular, ridged, splitting into 2-5 segments, A 2-30, development variable, pollen 4-8-zonoporate, G pseudomonomerous, bilocular, 1-locular by suppression, with 1 campylotropous ovule; testa single-layered, walls thin, endosperm with starch, embryo curved; n = 11. 1 genus, E. Asia to the Canary Islands, temperate. Included in Rubioideae by B. Bremer [1996]).

Cinchonoideae Rafinesque

Plants woody; route II carboxylated iridoids +, indole alkaloids; hairs mostly cylindrical; secondary polen presentation common; exotestal cells with perforations[?].

2. Luculia + Coptasapelta

(Raphides +).

2/21. Himalayas, China, to Malesia.

As Robbrecht and Manen (2006) emphasize, these two genera differ in having (or not) raphides, accumulating (or not) aluminium, and having pororate, acolumellate or tricolporate grains and distyly or secondary pollen presentation. Coptosapelta is an aluminium accumulator and also has raphides; it has T-shaped hairs, the corolla is contorted to the right, and the pollen is pororate (Verellen et al. 2004). For its pollen presentation, see Puff et al. (1996).

3. Cinchonidinae Robbrecht & Manen

Corynanthean and complex indole alkaloids +; (raphides + - Hamelieae); C left contorted, ovules often numerous; fruits usu. dry.

Timonius (150), Guettarda (80, but polyphyletic - see Achille et al. 2006). Pantropical.

For relationships in Naucleae, see Razafimandimbison & Bremer (2002).

Synonymy: Catesbaeaceae Martynov, Cephalanthaceae Rafinesque, Cinchonaceae Batsch, Coutareaceae Martynov, Guettardaceae Batsch, Henriqueziaceae Bremekamp (aliform-confluent xylem parenchyma; monosymmetric corolla. 2 genera, South America. Al-accumulation, secretory sacs, vestured pits, testa anatomy, etc., but no raphides, no colleters), Naucleaceae Wernham

4. Ixoridinae Robbrecht & Manen

(Calycophylls +), C contorted or cochleate, (stigma not bilobed - e.g. Gardenia), ovule number variable; fruits often fleshy.

Pavetta (400), Ixora (300), Mussaenda (200, but possibly polyphyletic - see Alejandro et al. [2005]: sepals large and colored), Randia (100), Coffea (110: include Psilanthus, see Maurin et al. 2007 for a phylogeny), Gardenia (60), Bertiera (55). Pantropical.

For phylogenetic relationhips within the subfamily, see Andreasen and Bremer (1996), for those within Vanguerieae, see Lantz and Bremer (2005) and references, for the circumscription of Coffeeae, see A. Davis et al. (2007) and for that of Sabiceeae, see Khan et al. (2008). Puff et al. (1996) and de Block and Igersheim (2001) discuss secondary pollen presentation, which is notably common here. [Naucleae + Hymenodictyeae] are a well supported clade sister to the only moderately (jacknife) supported remainder of Cinchonoideae (Andersson & Antonelli 2005), Luculia and Coptasapelta excepted.

Cronquist (1981) placed Dialypetalanthaceae adjacent to Pittosporaceae in the Rosales. Dialypetalanthus is an odd genus: K free, C free, opposite K, both in two decussate pairs, A (8-)16-17(-25), not epipetalous, basally connate, basifixed, porose, G [2] - oil glands are described as being pervasive (Goldberg 1986). RbcL data suggest that it is to be included in Ixoroideae (Fay et al. 2000b: Cinchonoideae here).

Synonymy: Coffeaceae Batsch, Dialypetalanthaceae Rizzini & Occhioni, nom. cons., Gardeniaceae Dumortier, Randiaceae Martynov, Sabiceaceae Martynov

• Members of the family can be recognised in the vegetative state by their opposite, sometimes whorled, and entire leaves that often dry blackish and interpetiolar stipules that have axillary colleters. The ovary is inferior, the flowers are polysymmetric, often with a narrow corolla tube and spreading lobes, and are quite often rather small and aggregated into heads.

Rubiaceae are not often eaten by caterpillar larvae of butterflies (Ehrlich & Raven 1964), although some sphingids (Semanophorae) prefer members of the family (Forbes 1956).

Myrmecodium, Hydnophytum and related genera placed in Hydnophytinae are epiphytic Malesian ant plants, the ants living in chambers in the grossly swollen stem (hypocotyl) base. Nutrients from the material brought in by the ants and stored in chambers of distinctive morphology is taken up by the plant. Some species have more or less branched root spines arising from the stem, inflorescence, end even the torn and eaten surfaces of the leaves (Huxley 1978; Jebb 1991; see Huxley & Jebb 1991 for the taxonomy of the group). Myrmecophily has arisen several times in Rubiaceae, and there are several myrmecophytic Naucleeae, the ants living in hollowed stems in plants with a much more "normal" appearance than many Hydnophytinae; some myrmecophytic clades of Naucleeae seem to have diversified notably slowly and/or have very limited distributions (Razafimandibison et al. 2005). Bacterial leaf nodules are known from some African species of Psychotria, and this seems to be associated with development of distinctive colleters (Lersten 1974 and references). Bacteria of the ß-proteobacterium Burkholderia have recently been isolated from these nodules (van Oevelen et al. 2004); the genera Pavetta and Sericanthe also have leaf nodules. Burkholderia is also known to be a nitrogen-fixing symbiont in the root nodules of some Faboideae. However, early studies failed to detect fixation of nitrogen (Miller 1990).

In Galium there are whorled "leaves" whose exact nature is a matter of some dispute, but there are only two, opposite branches per node, suggesting that the basic construction of the plant is of paired, opposite leaves; this is confirmed by the pattern of vascularization in most species (e.g. Neubauer 1981), but not in taxa like Galium rubioides which has four large leaves at the node all of which are directly vascularized from the stele (Rutishauser 1999). Most taxa in Rubiaceae have 1:1 nodal anatomy, only some twelve genera being trilacunar (Neubauer 1981); how this fits in the context of the family phylogeny is unknown. Unilacunar nodes are unusual in taxa with stipules (Sinnott & Bailey 1914), but lateral branches of the traces diverge and form a vascular collar around the stem from which the stipular bundles themselves diverge (Majumdar & Pal 1958). Stipule morphology and position in general shows considerable variation; there are sometimes two pairs of stipules, one more or less intrapetiolar, the other interpetiolar. Genipa and Posoqueria have a deeply lobed lamina; "latex" is not uncommon. Anisophylly is well known in the family, occuring also in taxa like Theligonum and Argostemma, being especially marked in taxa like A. humilis. A few Rubiaceae, including Theligonum, have more than twice the number of stamens as sepals/petals (Endress 2003a). Taxa like the related Gaertnera and Pagamea have secondarily superior ovaries (Igersheim et al. 1994). There is considerable variation in ovule morphology (Maheshwari 1950).

The position of Luculia and Coptosapelta now seems moderately well supported; they form a clade that is sister to the rest of Cinchonoideae. However, the two genera differ considerably in major characters so assigning polarity to, say, raphide presence in the family becomes rather tricky. The basic phylogenetic structure in the family is [Rubioideae + Cichonoideae], and in the latter relationships are [[Luculia + Coptosapelta] [Cinchonidinae + Ixoroidinae]] (see B. Bremer 1999; Rova et al. 2002; especially Robbrecht & Manen 2006). I follow the classification in Robbrecht and Manen (2006) except that I have not given a name to the [Luculia + Coptosapelta] clade pending the establishment of a firm cladistic resting place for it. Robbrecht and Manen (2006) should be consulted for a detailed discussion on taxon limits, formal classification, listing of sampled genera, etc.

For information on Rubiaceae, see Verdcourt (1958: general), Wunderlich (1971: Theligonum), Koek Noorman (1977: wood), Rogers (1984: Gleasonia, etc.), Rutishauser (1984: stipules), Robbrecht (1988, 1993: general), B. Bremer and Eriksson (1992: fruits and dispersal), B. Bremer et al. (1995: major groupings), Robbrecht et al. (1996: general), Claßssen-Bockhoff (1996a: survey of flower-like inflorescences), Puff et al. (1996: survey of secondary pollen presentation), B. Bremer (1996b: phylogeny), Piesschaert et al. (1997: Dialypetalanthus), Huysmans et al. (1997: orbicules in Cinchonioideae), Rutishauser et al. (1998: Theligonum), B. Bremer and Manen (2000: phylogeny and classification in Rubioideae), Vinckier et al. (2000: orbicules in Ixoroideae), Jansen et al. (2002a, 2003: Al accumulation), Delprete (2004: morphology), Rogers (2005: useful summary) and Dessein et al. (2005a) and Verellen et al. (2007), both pollen, not really a great help taxonomically. I am grateful to Elmar Robbrecht for help with the synonymy.

Gentianaceae + Loganiaceae + Gelsemiaceae + Apocynaceae: route I secoiridoids +; internal phloem +; C tube formation late, syncarpy postgenital.

GENTIANACEAE Jussieu, nom. cons.   Back to Gentianales

Herbs to shrubs (trees), mycorrhizal (and echlorophyllous); (plants Al-accumulators), no starch, but oligosaccharides +, monoterpene indole alkaloids, tannins 0; plants glabrous; cork?; (vessel elements with scalariform perforations); rays often 0; parenchyma septate; nodes 1 or more:1 or more; mucilage cells + (0); (stomata anisocytic); leaves sessile, usu. connate basally, ptyxis variable, 2ndary veins ± palmate (pinnate), (stipules +); flowers 4-5(-16)-merous, C right-contorted, marcescent, (tube formation intermediate), A (extrorse; placentoids +; tapetum amoeboid), basally connate, disc 0, G ?transverse, integument 2-20 cells across, antipodal cells diploid to polyploid, stigma broadly 2-lobed (capitate), wet; fruit a septicidal capsule, calyx often prominent; exotestal cells (± elongated), inner walls variously thickened (not); embryo white or green; 100 bp deletion in trnL gene.

87[list]/ca 1655 - 6 tribes below. World-wide, but especially temperate (Map: from Gillett 1963; Hultén 1958, 1971; van Steenis & van Balgooy 1966; Klackenberg 1985; Ho & Liu 2001; Struwe & Albert 2004). [Photo - Flower, Flower.]

1. Saccifolieae (Maguire & Pires) Struwe, Thiv, V. A. Albert & Kadereit

(Echlorophyllous herbs; shrubs); chemically unknown; (leaves spiral); flowers (heterostylous), (4-)5(-6)-merous, placentation parietal; (endosperm cellular - Voyriella; cotyledons 0); n = 10-14.

4/19. tropical South America, Panama.

The distinctive Guayanan Saccifolium is in a clade with Curtia, Voyriella, etc., sister to all other Gentianaceae (Thiv et al. 1999; Struwe et al. 2002; cf. Struwe et al. 1998); the glandular bodies in the leaf axils are best interpreted as colleters.

Synonymy: Saccifoliaceae Maguire & Pires (Subshrub; rays 0; stomata anisocytic; leaves spiral, apically saccate abaxially; flowers single, axillary; K basally connate, nectary-like disc on base inside, C imbricate, connective prolonged)

2. Exaceae Colla

Flowers (4-)5-merous, K connate or not; anticlinal walls of exotestal cells sinuous; n = 9, 11, 15, etc.

6/165: Sebaea (60), Exacum (70, including the mycoheterotrophic Cotylanthera). Africa, esp. Madagascar, Indo-Malesia, and to Australia and New Zealand (some Sebaea).

Flavone-O-glycosides are known from two species of Exacum, alone in the family. Exacum also has an imbricate corolla; the plant may be foetid, and Exacum (Cotylanthera) has straight [atropous], ategmic ovules (cf. some Voyria!).

For the phylogeny of Exaceae, see Yuan et al. (2003).

Chironieae + Helieae + Potalieae + Gentianeae: xanthones, L-(+)-bornesitol +; placentation parietal.

3. Chironieae (G. Don) Endlicher

(Shrubs); distinctive 6-substituted xanthones; flowers (2-)4-5(-12) merous, K connate, (pollen in tetrads); n = 10, 13-15, 17, etc.

23/159: Centaurium (50). Tropics and warm N. temperate.

Synonymy: Chironiaceae Horaninow, Coutoubiaceae Martynov

Helieae + Potalieae + Gentianeae: nectary +.

4. Helieae Gilg

(Shrubs); (inter/intrapetiolar sheaths, stipules +); flowers (4-)5(-6)-merous, (pollen in tetrads, polyads), style often long, twisted and flattened when dry; n = ?

22/205: Macrocarpaea (110). Tropical Central and South America, Caribean.

For the diversity of stipule-like structures in Macrocarpaea, see Grant and Weaver (2003).

5. Potalieae Reichenbach

Trees to lianes or herbs; C-glucoflavones +; nodes 5 or more:5 or more; cortical sclereids + [Fagraea]; (inter/intrapetiolar sheaths, auricles + [= "stipules"]); flowers 3-16(-24)-merous, K basally connate; (fruit a berry); n = ?

13/154: Fagraea (75), Lisianthus (30). Pantropical.

Potaliinae - timber trees; nodes multilacunar; sclereids +; flower to 16-merous [Anthocleista, Potalia], C deciduous, pollen porate, G fusion congenital; fruits berries - Anthocleista (seedling leaves over 2 m long), Fagraea, and Potalia

6. Gentianeae Colla

Distinctive xanthones, C-glucoflavones +; (nectary on C - Swertia et al.), style often short or 0; n = 5<, very variable.

17/950: Gentiana (360: mucilaginous seeds - see Ho & Liu 2001), Gentianella (250: polyphyletic, von Hagen & Kadereit 2001), Halenia (80), Swertia (135: fimbriate appendages and nectaries on petals sometimes present, ?polyphyletic - Chassot et al. 2001; Kadereit & von Hagen 2003). North temperate, to the Celebes (some Tripterospermum) and Africa and Madagascar (some Swertia).

Gentiana has ovules over almost the entire inner surface of the loculus.

Synonymy: Obolariaceae Martynov

• Gentianaceae often lack vegetative indumentum; many are bitter-tasting herbs. Their almost sessile, entire, opposite leaves are joined at the base and have ascending venation, and their rather large flowers (not the saprophytes) have a relatively large, persistent calyx, an often marcescent corolla with right-contorted lobes and a bicarpellate gynoecium with parietal placentation. The placentae are deeply bilobed and protrude into the ovary cavity.

Anthocleista, Fagraea, and Potalia used to be in Loganiaceae (Struwe & Albert 2000), but details of their iridoid chemistry are very gentianaceous and they are well embedded in the family (e.g. Backlund et al. 2000). Emblingia has been placed here (Savolainen et al. 2000a), but a position in Brassicales (q.v.) is justified on both molecular and morphological grounds.

Voyria, a genus of echlorophyllous saprophytes, is unplaced. Root hairs are generally absent (present in V. primuloides); pollen is 1-6-porate; species with straight [atropous] ovules lack an integument and those with anatropous ovules have a single integument; there is an endothelium and a nucellar cap; the endosperm is cellular or nuclear and almost absent, and the embryo is undifferentiated. There are sometimes two almost stamen-like appendages on either side of the ovary. n = 16-20 (Wood & Weaver 1982; Maas & Ruyters 1986; Struwe et al. 2002). It is found in America, but one species (V. primuloides) in Africa (Map: from Maas & Ruyters 1986; Raynal-Roques 1967) (= Voyriaceae Doweld).

The plants are often bitter-tasting because of the iridoids they contain. 1:3 nodes are scattered through the family, e.g. Exacum, Gentiana and Sabatia. Corolla tube formation for some taxa has been described as being late-early. Halenia has a corolla tube with five spurs. Endothelium is reported (Kapil & Tiwari 1978), however, as Shamrov (1996) describes this, it consists of one or two layers of cells of the integument that are elongated periclinally, not more or less anticlinally enlarged, as is common.

For ovule development, see Shamrov (1996), for orbicules, see Vinckier and Smets (2000a), for chemistry, see Jensen and Schripsema (2002: the first two tribes mentioned above need particular study), and for general information, see Struwe and Albert (2002) and Gentian Research Network.

Loganiaceae + Gelsemiaceae + Apocynaceae: ?

LOGANIACEAE R. Brown, nom. cons.   Back to Gentianales

Annual herbs to shrubs or lianes; tryptophane-derived alkaloids, quercetin, kaempferol +; nodes 1:1 or 3:3 (split laterals); stomata?; leaves ± flat, (2ndary veins palmate), joined by line or stipule sheathing; flowers 4- or 5-merous, (median K abaxial - Logania; monosymmetric - Usteria); K basally connate or not, C (valvate), often hairy at the mouth, (A 1, abaxial - Usteria), disc 0, poorly developed, or nectary on walls of G, G often partly inferior and partly apocarpous, placentation axile, -1 ovule/carpel, styles 0, or styles + (carpels congenitally syncarpous; postgenitally connate apically only), stigma capitate, long-clavate, 2-lobed, or punctate; fruit a follicle, loculicidal and/or septicidal capsule, drupe or berry; seeds often embedded in pulp/placentae swollen, exotestal cells papillate or hairy, ± thick-walled and lignified except outer wall; endosperm starchy or hemicellulosic, horny; n = 10, 12, 16; seedings epigeal and phanerocotylar.

13[list]/420: Strychnos (190: branch tendrils), Mitrasacme (55: "intermediate" endosperm), Geniostoma (55). Pantropical, esp. Australia and New Caledonia (Map: from Leenhouts 1962; van Steenis & van Balgooy 1966; Leeuwenberg 1969). [Photo - Flower, Fruit]

The wood of Strychnos has included phloem. Mitrasacme has an endothelium. Mitreola oldenlandioides has straight [atropous] ovules and cellular endosperm (Reddy et al. 1999). Colporate pollen without lateral extensions at the endocolpus reported to be a character unique (in this group) to Strychnos and its immediate relatives.

For information, see Hasselberg (1937: nodes and stipules), Leeuwenberg (1980: general), Keller (1996: "stipules"), and Hakki (1998: Usteria).

Synonymy: Antoniaceae Hutchinson, Gardneriaceae Perleb, Geniostomaceae Struwe & V. Albert, Spigeliaceae Martius (herbs; leaves often pseudoverticillate; inflorescence a cincinnus; late corolla tube formation [Spigelia]; fruit a septicidal+loculicidal capsule, the valves all falling off), Strychnaceae Perleb

Gelsemiaceae + Apocynaceae: nodes 1:1; seeds ± flattened.

Backlund et al. (2000) note that C17 indole alkaloids, the number of tapetum layers, and cytology support this relationship - and the presence of quercetin and kaempferol, imbricate corolla, and horny (starchy) endosperm moight support a close relationship with Loganiaceae.

GELSEMIACEAE Struwe & V. Albert   Back to Gentianales

Shrubs or lianes; quercetin, kaempferol +; true tracheids +; stomata?; leaves connected by a ridge, or stipules 2, interpetiolar or short sheathing; flowers heterostylous, A extrorse [Gelsemium] or latrorse, style twice bifid; fruit a loculicidal and/or septicidal capsule, K persistent; seeds winged or hairy; testa?; endosperm horny, starchy; n = 8, 10.

2[list]/11. ± tropical; South East Asia, Africa, America (Map: from Leeuwenberg 1961; van Steenis & van Balgooy 1966). [Photo - Gelsemium Collection © M. Dirr, Flower (Pin), Flower (Thrum).]

Pteleocarpa, a poorly known and rather odd west Malesian genus in which the leaves as well as the flowers are yellow when the flowers are open, is probably to be placed here; it was previously included in Boraginaceae s.l., but as an anomalous genus (Olmstead & Ferguson 2001). It has not been incorporated into the description; it has i.a. spiral leaves, two ovules/carpel, and a single-seeded, more or less orbicular samara; when in flower, the whole branch is yellow, the leaves having become a color similar to that of the yellow corolla. Brummitt (2007) recognized this as a separate family.

For the phylogeny and biogeography of the family (Pteleocarpa not included, see Jiao and Li (2007)

Vascular pits in Gelsemium are not vestured (Rogers 1986), those of Pteleocarpa are. The latter also has mainly apotracheal parenchyma in unilateral, uniseriate bands and fiber tracheids with bordered pits (Gottwald 1982).

APOCYNACEAE Jussieu, nom. cons.   Back to Gentianales

Lianes to trees (herbs); tryptophane-derived and steroidal alkaloids, cardenolides, route II decarboxylated iridoids +, tanniniferous; (cork deep-seated - Rhazya); pericyclic fibers 0 [always?]; (vessel elements with scalariform perforations); non-articulated (articulated) laticifers +; (petioles also with adaxial bundles); stomata also paracytic (actinocytic); leaves (spiral), usu. flat or conduplicate, ("stipules" cauline); K with basal adaxial colleters, C left-contorted, postgenital connation forming the upper [above the insertion of the A] tube, corona from C, A ± connivent, filament short, pollen transported in foam, (nectary on outer wall of ovary, 0), G (-8), (connate - Allamanda, Carissa; transverse), (ovules hemitropous), styles elongated, usu. apex alone postgenitally syncarpous, stylar head swollen, wet or dry; (seeds rounded); testa multiplicative, exotestal cells with all walls thickened (unthickened - Periploca), (flattened mesotestal crystalliferous cells); extensive polyploidy including triploids, protein crystalloids in the nuclei.

415[list]/4555 in five groups below. Largely tropical to warm temperate (map: from ). [Photo - Flower] [Photo - Fruit]

1. Rauvolfioideae Kosteletzky

Indole alkaloids +/0; (calycine colleters + - Tabernaemontaneae), anthers connivent (lignified basal appendages - Tabernaemontaneae), (pollen porate), G apocarpous or not, placentation then axile or parietal; fruit berry, drupe or follicle; (seed with coma - Haplophyton; aril - Tabernaemontaneae s. str.); n = (9 - esp. Alyxieae) 10, 11, (23).

84/980: Alyxia (120), Tabernaemontana (100), Melodinus (75), Rauvolfia (110), Landolphia (60). Tropical.

Quite probably paraphyletic, Tabernaemontaneae, etc., having an androecium and stigmatic head complex like that of Apocynoideae in particular. For a phylogeny of Tabernaemontaneae, see Simões et al. (2006a) and of Alyxieae, M. Endress et al. (2007) and of Rauvolfioideae as a whole, see Simões et al. (2007a).

Apocynoideae + Periplocoideae + Secamonoideae + Asclepiadoideae: iridoids 0 [this level?]; C right-contorted, anthers with lignified basal appendages [guide rails], adnate to style head, pollen porate, G apocarpous, stylar head radially differentiated; fruit a follicle; seeds comose.

The close association of the androecium and gynoecium to form the gynostegium is postgenital.

2. Apocynoideae Burnett

(C left-contorted; valvate), A inserted well below bases of corolla lobes; n = (6-)10, 11 (12).

77/860: Parsonsia (120), Mandevilla (115), Prestonia (65), Forsteronia (50). Largely tropical.

For phylogenetic relationships in Mesechiteae, see Simões et al. (2004, 2006b).

Synonymy (first two subfamilies): Carissaceae Bertolini, Cerberaceae Martynov, Ophioxylaceae Perleb, Pacouriaceae Martynov, Plumeriaceae Horaninow, Vincaceae Vest, Willughbieaceae J. Agardh

3. Periplocoideae Endlicher

C (valvate), tube formation intermediate, A inserted at top of C tube (etc.), (staminal feet erect, connate, forming tube around ovary), anthers without guide rails, pollen in tetrads, collected on translator [spoonlike structure + basal sticky viscidium]; embryo color?; n = 11 (mostly).

31/180. Old World, tropics to dry temperate (Map: Good 1952).

How the corolla tube is formed in this group is unknown. For relationships in the subfamily, see Venter and Verhoeven (2001). Parsonsia and Echites (see Apocynoideae above) may be part of this clade, whether or not they have a different tribal name (Echiteae: Sennblad & Bremer 2002).

Synonymy: Periplocaceae (Kosteletzky) Schlechter, nom. cons.

Secamonoideae + Asclepiadoideae: monoterpene indole alkaloids 0; C tube formation intermediate, A inserted well below bases of corolla lobes, corona usually staminal, filament 0, staminal feet erect, connate, forming tube around ovary, anthers inserted on top, pollen in tetrads, tetrads tetragonal [microsporogenesis successive], grains inaperturate, psilate, aggregated into pollinia, pollinia of one pollinarium from half anthers of adjacent stamens, orbicules 0, translator [retinaculum] of hardened resinous secretion [mostly stigmatic] and apical adhesive corpusculum, nectaries behind guide rails; endosperm nuclear (cellular), embryo green; n = 11.

For pollen morphology, see Verhoeren and Venter (2001).

4. Secamonoideae Endlicher

C also left-contorted, pollinia 4, lacking outer wall, translator arms [caudicle] 0, granular layer of exine thick.

9/170: Secamone (100). Old World, esp. Madagascar, tropics to temperate.

5. Asclepiadoideae Burnett

(Included phloem +); (leaves spiral); C also valvate, anthers bisporangiate [1 sporangium from each theca is lost], pollinia 2, caudicle + (0 - Fockeeae), anther secreting wall around pollinium, (pollen in tetrads, no pollinium wall - Fockea; orbicules + - Riocreuxia), granular layer of exine thin; n = (9-14).

214/2365: Cynanchum (200), Matalea (180), Ceropegia (160), Asclepias (100), Gonolobus (100), Marsdenia (100), Brachystelma (100), Hoya (90[-200]), Oxypetalum (90), Dischidia (80), Ditassa (75), Stapelia (70), Orbea (55), Huernia (50), Tylophora (50), Caralluma (47). Tropics to temperate, drier areas esp. in Africa (Map: see Good 1952). [Photo - Flower, Flower, Flower, Fruit.]

Genera with opposite leaves such as Hoya can have seedlings with spiral leaves (see also Absolmsia, previously segregated from Hoya, which has spiral leaves in the flowering stage). Estimates of species numbers in Hoya and Dischidia in particular vary widely.

For relationships within New World Asclepiadoideae, see Liede-Schumann (2005) and Rapini et al. (2007), and for a magnificent revision of southern African stapeliads, see Bruyns (2004). Hoya is a particularly speciose genus; see Wanntorp et al. (2006a, b) for phylogenies and Wanntorp and Forster (2007) for morphology.

Synonymy: Asclepiadaceae Borkhausen, nom. cons., Stapeliaceae Horaninow

• Apocynaceae usually have copious latex and the leaves are often opposite and with colleters; the venation of the dry lamina is not very prominent. A number of taxa are climbers. The corolla is often contorted and the stylar head is swollen and closely associated with the more or less connivent anthers. The two carpels are usually held together only by the stylar head; in fruit, they often diverge (if both are fertilised); follicles containing seeds with tufts of hairs at either end are common. The inflorescence may appear extra-axillary, being borne in the axils of scale leaves themselves borne after a reduced internode, or they may be lateral-axillary, as in many Asclepiadoideae (but Leptadenia is axillary!).

Caterpillars of Nymphalidae-Danainae relish members of this family (Ehrlich & Raven 1964; see Ackery & Vane-Wright 1984 for a comprehensive treatment), but they also eat other plants with latex, including several Moraceae; cardenolides are noxious and may protect both larva and adult. Brightly-colored danaine caterpillars and bright orange aphids are to be found on Asclepiadoideae in both North America and southern Africa. Pyrrolizidine alkaloids are known from some Apocynaceae, so they also attract adult Danainae and Ithomiinae which use these compounds as the basis of their pheromones (Boppreé 2005; Brehm et al. 2007); these alkaloids also occur in Crotalaria, some Boraginaceae and Asteraceae-Asteroideae. Interestingly, Ithomiinae preferentially visit bait with withered flowers, while Arctiidae moths prefer crushed roots; Brehm et al. (2007) suggest that the pyrrolizidine alkaloids of Prestonia (Echiteae) may have been originally involved in the phramacophagous behaviour by Ithomiinae butterflies which are now commonly found on Solanaceae (Wilmott & Freitas 2006). Hosts of seed-eating bugs of Hemiptera-Lygaeidae-Lygaeinae are concentrated in the old Apocynaceae (Slater 1976). For the possible co-evolution of the longicorn Tetraopes with Asclepias, see Farrell and Mitter (1998), and for a study of the different defence syndromes of Asclepias, see Agrawal & Fishbein (2006).

In some perhaps plesiomorphic taxa the stigma is swollen and sticky polysaccharide-terpenoid material is secreted to which the pollen adheres; there is no spatially-localized receptive and secretory areas on the stigma. Such taxa are found in basal grade of "Rauvolfioideae", however, it is possible that these stigmas have been derived more than once, and that the differentiated stigma described below is plesiomorphic for the whole family (Simõs et al. 2007a). In other taxa pollen is deposited on to the apex of the stigmatic head (again secondary pollen presentation), there is an annulus around the middle that aids in the removal of the pollen, and the stigma is a ring around the base. The gynostegium, formed by the post-genital fusion of anthers and stigma, develops in some "Apocynoideae" when the connective tissue of the anther becomes adnate to the stigmatic head (the staminal retinacle of Simões et al. 2007b). Pollen from thecae of adjacent anthers mixes, whereas pollen from the thecae of the same anther is more or less prevented from mixing by the zone of adnation of the connective, that is, the basic arrangement of the androecium is the same as that in Asclepiadoideae. Hairs on the anthers or stigmatic head, or lignified guide rails at the bases of the anther, are all involved in pollen presentation and guiding the pollinator so that effective pollination occurs (e.g. Fallen 1986). Since it is unlikely that Periplocoideae are sister to [Secamonoideae + Asclepiadoideae] (Potgeiter & Albert 2001; Sennblad & Bremer 2002; esp. Livschultz et al. 2007), details of the evolution of the pollinarium of the two latter is unclear. Moreover, variation in the pollinarium of Fockeeae (which includes both Fockea and Cibirhiza), sister to all other Asclepiadoideae, also confuses the issue (see Verhoeven et al. 2003). In any event, the old idea of the evolution of the pollinia of Asclepiadaceae via Periplocaceae/Periplocoideae as some sort of intermediate needs to be revised (see also Ionta & Judd 2007). Wyatt and Lipow (2007) suggest that the evolution of pollinia and the secondary apocarpy in Asclepiadoideae and Apocynaceae s.l. (at least some Ascleiadoideae have no compitum developed at all) is connected with the post-zygotic incompatibility system that characterises Apocynaceae (?all) and at least some other Gentianales.

The classification here is based on that of M. Endress et al. (2007a; see also Endress & Bruyns 2000), however, generic limits need attention (see e.g. Liede & Täuber 2000; Liede et al. 2002; Rapini et al. 2003; Goyder et al. 2007l; Meve & Liede-Schumann 2007). Note also that both Rauvolfioideae and Apocynoideae are paraphyletic (Sennblad & Bremer 2002); see Livshultz et al. (2007) for the phylogeny of "Apocynoideae" and Simões et al. (2007) for that of "Rauvolfioideae". Because of such problems, any classification can only be highly provisional (e.g. M. Endress 2004).

"Rauvolfioideae" are highly paraphyletic. The relationships of seven tribes are more or less clear, but those of the remaining five tribes remain to be established; there is good support for Aspidospermeae as sister to all other Apocynaceae (Simões et al. 2007). Within "Apocynoideae" genera in major clades usually come wither from the Old or New Worlds, with little movement between the two (Livschultz et al. 2007). A small African clade, Baisseeae, has strong support as sister to [Secamonoideae + Asclepiadoideae], and below Baisseeae is a polychotomy including an Asian clade of "Apocynoideae", Rhabdadenia, Periplocoideae, etc. (Livshultz et al. 2007; see also Lahaye et al. 2007). Within Periplocoideae Phyllanthera is sister to the rest; pollinia seem to have evolved at least three times (Ionta & Judd 2007). Generic limits in Asclepiadoideae seem to be particularly difficult. Asclepias itself is definitely polphyletic, the New World clade including the type of the genus (Goyder et al. 2007). Ceropegieae are another difficult area, Ceropegia itself occuring all over the tree (Meve & Liede-Schumann 2007).

The cambium is occasionally storied. The leaves of Asclepiadoideae and many genera more basal to them have flat ptyxis (Cullen 1978). In taxa such as Vallesia there are cauline "stipules", apparently colleters in a stipular position (Vallesia also has spiral leaves), while in Mandevilla there is a distinctive ring of large, radiating, almost fleshy projections immediately below the leaves. A variety of stipule-like structures are found in Stapelia and relatives; in Edithcolea grandis the "stipule" is represented by a single hair (Bruyns 2000, see also 2004). In other Apocynaceae there is an adaxial excavation at the base of the petiole in which the axillary bud is enclosed, often surrounded by secretions from the colleters. The "lateral" inflorescences of at least some stapeliads may be displaced-terminal (Bruyns 2004). Endothelium is reported in Apocynaceae s. str. (Kapil & Tiwari 1978; Cronquist 1981), but it is absent according to Rohwer (1996).

When the carpels are connate, placentation may be axile or parietal. Syncarpy seems to have evolved more than once in the family, it may be congenital (Acokanthera) or postgenital (Allamanda) (Sennblad & Bremer 1996). The carpels may be collateral (Spichiger et al. 2002).

Apocynaceae are a much-studied group, see Leeuwenberg (1983: Plumerioideae), Liede and Weberling (1985) and Steck and Weberling (1982), both inflorescence, Nilsson et al. (1993: pollen), P. Endress (1994: much floral morphology), Sennblad (1997: general), Sennblad and Bremer (1996: rbcL phylogeny, morphology), Civeyrel et al. (1998: comparison of molecular phylogeny with variation in the pollinaria), M. Endress and Bruyns (2000, much general information), Albers and Meve (2001: karyology), Verhoeven and Venter (2001: pollen), Vinckier and Smets (2002b: orbicules), Kunze (2006: morphology, development and evolution of the corona) and Demarco et al. (2006: laticifer type). There is much information on Periplocoideae, Secamonoideae, and Asclepiadoideae at a site run by S. Liede-Schumann and U. Meve. I thank M. Endress for comments.