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, branching endogenous; arbuscular mycorrhizae +; shoot apical meristem complex; stem with ectophloic eustele, endodermis 0, xylem endarch, branching exogenous; vascular tissue in t.s. discontinuous by interfascicular regions; vascular cambium + [xylem ("wood") differentiating internally, phloem externally]; wood homoxylous, tracheids +; tracheid/tracheid pits circular, bordered; sieve tube/cell plastids with starch grains; phloem fibers +; stem cork cambium superficial, root cork cambium deep seated; nodes ?; stomata ?; leaf vascular bundles collateral; leaves spiral, simple, axillary buds?, prophylls [including bracteoles] two, lateral, veins -5(-8) mm/mm²; plant heterosporous, sporangia eusporangiate, on sporophylls, sporophylls aggregated in indeterminate cones/strobili; true pollen [microspores] +, grains mono[ana]sulcate, exine and intine homogeneous, ovules unitegmic, crassinucellate, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development first endo- then exosporic, tube developing from distal end of grain, to ca 2 mm from receptive surface to egg, gametes two, with cell walls, with many flagellae; female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large", first cell wall of zygote transverse, embryo straight, endoscopic [suspensor +], short-minute, with morphological dormancy, white, cotyledons 2; plastid transmission maternal; two copies of LEAFY gene, PHY gene duplication, 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 [ANITA grade?], 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, development in general centripetal, numbers unstable, P not differentiated, outer members not enclosing the rest of the bud, A many, with a single trace, introrse, filaments stout, anther ± embedded in the filament, tetrasporangiate, dithecal, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally by action of hypodermal endothecium, endothecial cells elongated at right angles to long axis of anther, tapetum glandular, binucleate, microspore mother cells in a block, microsporogenesis successive, pollen subspherical, binucleate at dispersal, trinucleate eventually, tectum continuous or microperforate, exine columellar, endexine thin, compact, lamellate only in the apertural regions, pollen germinating in less than 3 hours, tube elongated, growing at 80-600 µm/hour, with callose plugs and callose-based walls, penetrating between cells, siphonogamy, penetration of ovules within ca 18 hours , 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; 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.

ASTERIDS - Sympetalae redux?  Back to Main Tree

Nicotinic acid metabolised to its arabinosides, caffeic acid derivatives +, (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; endosperm cellular.

See the Dilleniales page for discussion on the relationships of the asterids, which have no firm position as yet; Caryophyllales may be their sister group.

The age of the stem group asterids may be ca 128 million years before present, mid Early Cretaceous, the Cornales and Ericales diverging soon afterwards, and the other asterid orders all diverging over 100 million years before present (K. Bremer et al. 2004); Wikström et al. (2003) suggest a crown group age of 117-107 million years before present, while Anderson et al. (2005: asterids other than Cornales and Ericales not sampled) suggest figures of ca 112 million years before present for the stem group, ca 109 million years before present for the crown group.

Iridoids, common in asterids, have been implicated in herbivore preferences, detering some and attracting others (e.g. see discussion under Plantaginaceae, Scrophulariaceae, etc.: Bowers 1980, 1988); iridoids have a bitter taste and are emetics for vertebrates, at least. Iridoids are sometimes sequestered by the insect and used in its defence against predators (Nishida 2002 for a summary). Thus Uraniidae (moths) are found on Dipsacales, Lamiales, Gentianales - and also Daphniphyllaceae (an iridoid-containing member of Saxifragales - see Lees & Smith 1991), while larvae of Nymphalidae-Melitaeini butterflies are also almost restricted to asterids, although in this case they also quite common on Asteraceae and Acanthaceae, which, although asterids, lack iridoids; Melitaeini distinguish between plants with route I secoiridoids, which they eat, and route II decarboxylated iridoids (iridoid glycosides), which they do rarely eat (Wahlberg 2001).

In the asterids, compound leaves are relatively uncommon, and the leaflets are often not articulated and/or distinct. Taxa with stipules are also fairly uncommon, as are those with apetalous flowers and arillate seeds. Sympetalae of older studies were defined largely by their sympetalous corolla; monosymmetry may have arisen some fifteen times in the asterids, with reversal in Lamiales and Dipsacales (Jabbour et al. 2008: see also Donoghue et al. 1998; Ree & Donoghue 1999). Such flowers may have one, or rarely two, spurs (Jabbour et al. 2008). Lee et al. (2004) suggest that the CRABS CLAW gene is expressed in the rather different nectaries in the rosids (receptacular nectary) and asterids (gynoecial nectary) that they sampled; Bernadello (2007) surveys nectary variation in asterids.

Albach et al. (2001a) discuss iridoid distribution, etc., in the asterids, as do Soltis et al. (2005b), Mølgaard and Ravn (1988) and Rønsted et al. (2002) outline the systematic utility of caffeic acid derivatives; chlorogenic acid, an ester of caffeic and quinic acid, is especially common in asterids, but also occurs elsewhere (see also also Lamiales and Boraginaceae in particular for other derivatives). Characteristic of the whole clade - although with numerous exceptions (derived), is the Baileyan wood anatomical syndrome of predominantly solitary vessels, scalariform perforation plates, mainly opposite vessel pitting, very long vessel elements and fibers at least 800 and 2190 µm long respectively, non-septate fibers with distinctly bordered pits, and diffuse to diffuse-in-aggregates and scanty paratracheal axial parenchyma (Lens et al. 2008). K. Bremer et al. (2001) suggest some morphological synapomorphies for groupings. Some characters common in asterids probably have functional and logical linkages that also must be taken into account. Thus the presence of a tenuinucellate nucellus is linked with that of unitegmic ovules, the development of an endothelium (Kapil & Tiwari 1978), and a simple exotestal seed type (Netolitzky 1926); that of sympetalous monosymmetric flowers with epipetalous stamens, etc.

Some families here included in the asterids seem to be polypetalous, but developmental studies like those of Erbar (1991) may show they have a ring primordium very early on (see, for example, Reidt & Leins 1994). The position of early initiation of the corolla tube on the tree is quite uncertain. Apiales + Asterales + Dipsacales have many members with such initiation (see Apiales page for further discussion), as do both Oleaceae and Rubiaceae, "basal" or almost so in their orders in asterid I group, and so do some Cornales. Sampling leaves a great deal to be desired, but the condition of early initiation could conceivably be a synapomorphy for the asterids (see Erbar & Leins 1996b; Leins & Erbar 2003b for details); it is, however, only in Ericales and other asterids that the mature flower may have a corolla tube, hence the corolla tube apomorphy in asterids and in [Ericales + other asterids]. Note that a tube-forming hypanthium is rare in asterids, cf. rosids. In general, where many characters are to be placed on the tree depends on resolution of relationships within Ericales and Cornales, and the pattern of gain-loss of some of these features is liable to be rather complex; even the relative position of these two clades within asterids needs further support.

Ericales and Cornales in particular show much variation in the degree of sympetaly, stamen number, adnation of stamens to corolla, and in ovule morphology and anatomy; some of this variation is like that found in rosids, Dilleniales, etc., and unlike that in the asterids. They may also have ellagic acid, which has a rather similar distribution (but cf. iridoids). For further discussion of this variation, see the asterids.

The monophyly of the asterids is well established (e.g. Olmstead et al. 1992, 1993, 2000; P. Soltis 1999); Albach et al. (1998) suggest the four main groupings recognised here. A phylogeny proposed by K. Bremer et al. (2001) is based on an analysis of 2 genes + morphology, one by Albach et al. (2001b) on four genes; relationships suggested by these studies are largely congruent. Differences are almost entirely in taxa not assigned to orders by A.P.G. (1998), although many of these may be assignable if the relationships suggested in the still provisional Bayesian analyses of Lundberg (2001b, d) hold. B. Bremer et al. (2002) provide a recent comprehensive phylogeny of the clade, although with minimal sampling within families, using three coding and three non-coding chloroplast markers. Both B. Bremer et al. (2003) and Olmstead (2000) suggest that there is strong support for Cornales being the sister to all other asterids; see also Albach et al. (2001) and Soltis et al. (2003). However, Hilu et al. (2003) reverse the positions of Cornales and Ericales, but the matK gene alone was sequenced. Note that in their study, Caiophora (Loasaceae) appears in Asterales, far separate from the other members of the family in the analysis - perhaps mistaken identity?

The distinction between the other angiosperms and the asterids partly corresponds to the distinction between the crassinucellate and tenuinucellate groups of Young and Watson (1970, based on phenetic analyses). There are also substantial differences, for example, Young and Watson included Apiaceae-Araliaceae in their crassinucellate group. Philipson (1974) further emphasized the distinction between the crassinucellate and tenuinucellate groups of Young and Watson, linking the two via Celastraceae, Grossulariaceae and Brexiaceae (here Celastrales, Saxifragales, and Crossosomatales); Theales, Primulales and Ebenales together made up a separate lineage (here part of Ericales). Later Philipson (1977) resurrected van Tieghem's (1901) names Unitegminae and Bitegminae for these two groups; integument number and nucellus condition are correlated.

CORNALES Dumortier   Main Tree, Synapomorphies.

Iridoids diverse, ellagic acid +, flavones 0; vessel elements with scalariform perforations; nodes 3:3; inflorescence cymose; (flowers 4-merous), C valvate, apparently free, tube formation early, A basifixed, G inferior, crowned with disc-like nectary, 1-2 apical ovules/carpel, ventral carpellary bundles in the carpel wall [transseptal bundles, i.e. vascular bundles to ovules go over the top of the septum and then down; there are no bundles running up the central axis of the gynoecium]; fruit drupaceous, with apical germination valve(s) in the stone, K persistent. - 7 families, 51 genera, 590 species.

Fruits of this small clade are well represented in the fossil record (Manchester et al. 2007) and are datable to the Maastrichtian, ca 70 million years before present (Nyssa) and Coniacian, ca 87 million years before present (Takahashi et al. 2002: Hironoia); Anderson et al. (2005) suggest figures of ca 109 million years before present for the stem group, 101-97 million years before present for the crown group.

The strands of apotracheal parenchyma are relatively long (at least 9 cells long) in Cornaceae s.l. (inc. Curtisiaceae) when compared with some of their putative relatives (Noshiro & Baas 1998). Spirally-thickened vessels holding the two halves of transversely-torn leaves together are quite common... Teeth of Nyssaceae and Hydrangeaceae have a clear apex with a foramen, higher order laterals are involved (Hickey & Wolfe 1975). The petals may be free, but corolla tube formation, when known, is early (e.g. Reidt & Leins 1994).

Takhtajan (1997) included Hydrangeales in Cornidae-Cornanae, but Loasales-Loasanae were part of his Lamiidae. 11/15 of the genera of Cornaceae s.l. have been placed in monotypic families, or the family has been circumscribed very broadly, as by Mabberley (1997). Molecular studies (e.g. Xiang et al. 1993) suggest a break-up of the family; the core is here. Relationships between genera in this core are unclear, but at least some aggregation of the families they represent is in order (e.g. Albach et al. 2001b; Xiang et al. 2002), indeed, relationships in Cornales as a whole are unclear. Although Cornus is sister to Mastixiaceae in some morphological trees (Murrell 1993), it is not close in rbcL trees (Xiang et al. 1993, 1997). For the relationships of Grubbiaceae and Hydrostachyaceae (placement of the latter is especially difficult), see especially Hempel et al. (1995), Xiang (1999), Soltis et al. (1997, 2000, 2007a), Savolainen et al. (2000b), Fan and Xiang (2003) and Xiang et al. (2002); the tree here is based largely on the last two papers. Note that the inclusion of Hydrostachys in analyses of Cornales considerably affects topologies and support values throughout the tree of the order. For other Cornales s.l., see e.g. Garryaceae (Garryales), Curtisiaceae (Solanales) and Griseliniaceae (Apiales).

This is the asterid IV group of some early phylogenetic studies.

For more details, see Faure (1924), Ferguson (1977: pollen), Sato (1976), Grayer et al. (1999: saponins), and Manchester et al. (2007: fossils and stone anatomy).

Includes Cornaceae, Curtisiaceae, Grubbiaceae, Hydrangeaceae, Hydrostachyaceae, Loasaceae, Nyssaceae.

Synonymy: Grubbiales Doweld, Hortensiales Grisebach, Hydrangeales Nakai, Hydrostachyales Reveal, Loasales Bessey - Cornanae Reveal, Loasanae Reveal - Cornidae Reveal

Cornaceae + Nyssaceae: (plants Al accumulators); route I secoiridoids, triterpenoid saponins +, tanniniferous; (mucilage +); hairs T-shaped, unicellular; flowers small, K notably small, pollen with complex endaperture [a pore joining two lateral thinnings parallel to the colpus], (archesporium multicellular), style short; (endosperm also nuclear).

It is not clear that these are sister taxa, nevertheless, they do have a number of features in common.

CORNACEAE Dumortier, nom. cons.   Back to Cornales

Trees and shrubs (stoloniferous subshrubs); flavonols, also route II decarboxylated iridoids, isoquinoline alkaloids +; (latex +); (vessel elements with simple perforation plates); sclereids +; petiole bundle arcuate, or D-shaped or annular (with medullary bundle); branching various; hairs (stellate), walls often with crystals; leaves opposite, bases joined by a line, spiral or two-ranked, conduplicate(-flat) or curved (both -plicate) or involute, margins entire (lobed), 2ndary veins pinnate or subpalmate; flowers 4(-10)-merous, K connate or not, stamens = and opposite sepals (-4x, anthers long - Alangium), pollen with H-shaped endapertures, often starchy, G [1-4] (1 loculus), ovules apotropous, (tenuinucellate - red-fruited Cornus), (style long, with long arms), stigma truncate to capitate, dry; fruit 1-2-seeded, stone walls of sclereidal cells; testa of elongated cells, much compressed (ca 6 cells thick, vascularized - Alangium); endosperm hemicellulosic, embryo green; n = 8-11.

2[list]/85: Cornus (65 spp). Scattered, not S. South America (Map: see van Steenis & van Balgooy 1966; Aubréville 1974; George 1984; Meusel et al. 1978; Hultén & Fries 1986). [Photos - Habit, [Photo: Cornus Inflorescence, Flower, Fruit.]

• Many Cornaceae are recognisable vegetatively by their T-shaped hairs and leaves often with entire margins and actinodromous venation, the lateral veins arching and proceeding towards the apex. The flowers are often small and aggregated into heads or other compact inflorescences; the flowers of one inflorescence open more or less together. The flowers have a small calyx, apparently free and valvate petals, an inferior ovary crowned by a disc and with 1-2 locules/carpel, and a 1-seeded drupaceous fruit.

Blue-fruited dogwoods have lost iridoids (Xiang et al. 1997). In nodes of Alangium the central vascular trace may immediately divide into three (nodes 3:5!). Mabberley (1997) describes Alangiaceae as having spiral leaves; they are often two-ranked. The floral organ diversity genes B and C are expressed in the large, white inflorescence bracts of Cornus (Maturen et al. 2005; see also Zhang et al. 2008 - extensive PI-like gene duplication). In Alangium there is a very little vascular tissue in the center of the ovary, while there is considerable variation in embryo sac development in Cornus in particular (Johri et al. 1992 for references).

For information, see Adams (1949: anatomy) and Eyde (e.g. 1968, 1988: flower and fruit in particular), Neubauer (1978: petiolar anatomy), Jensen et al. (1975a: iridoids), and Kubitzki (2004b: general). For relationships within Cornus, cf. Murrell (1993) and Xiang et al. (1993, 2006).

Synonymy: Alangiaceae Candolle, nom. cons.

NYSSACEAE Dumortier, nom. cons.   Back to Cornales

Trees and shrubs; route I secoiridoids +; (resin +); petiole bundles arcuate or with adaxial plate; leaves spiral (opposite), conduplicate [Nyssa], margins serrate or entire; plants andromonoecious, dioecious, etc., or flowers perfect; inflorescences various (capitate); flowers 4-5-merous; C ± imbricate, or valvate and inflexed at apex, or P 0, A 4-26 [often diplostemonous], G [5-10], (loculus and ovule 1), (styles +); endocarp fibrous; fruits 1-5-seeded, stone walls of fibrous cells [?an apomorphy]; (seed U-shaped - Mastixia), testa multiplicative, exotesta lignified; embryo long or short; n = 11, 13 [both Nyssa], 21, 22.

5/22. Mainly East Asia, also Indo-Malesia and E. North America (Map: see van Steenis & van Balgooy 1966; Matthew 1977). [Photo - Nyssa Flower, Fruit © H. Wilson.]

Fossils of Nyssaceae fruits are widespread in the northern hemisphere in the early Tertiary, some being 3- or 4-carpellate (Eyde 1997, for details), Mastixia was especially abundant in Europe 65-70 million years before present.

Davidia has flowers in capitula subtended by 2 large white bracts; it lacks a perianth and may have bitegmic ovules. Diplopanax has recently been placed in Mastixiaceae s. str. (Eyde & Quiyun 1990; cf. Xiang et al. 1997). It has five lobes on the disc opposite the corolla and a single-seeded fruit the embryo of which is C-shaped in transverse section (Ying et al. 1993), and it also contains petroselenic acid (Zhu et al. 1998 - they did not find it in Fatsia or Aucuba...). Petroselenic acid is found in a number of Apiales, and relationships between Cornaceae and some Apiales have been suggested in the past!

For the indole alkaloid camptothecin, see Lorence and Nessler (2004), for cytology, see He et al. (2004), for general information, see Kubitzki (2004b: as Cornaceae), for Mastixia, see Matthew (1976); embryological details are unknown for it and Diplopanax.

Synonymy: Davidiaceae H.-L. Li, Mastixiaceae Calestani

Hydrangeaceae + Loasaceae: similar route I secoiridoids and route II decarboxylated iridoids [e.g. deutzioside], flavonols +, ellagic acid 0; cork cambium deep-seated; hairs tuberculate, walls calcified, with basal cell pedestals; leaves opposite, with glandular teeth (lobed); A (initiated as antesepalous triplets), (2x C-)many, placentation parietal, gynoecium with axial/central vascular bundles, many tenuinucellate ovules/carpel, stigma dry; fruit septicidal, (persistent placental strands +); exotestal cells variously elongated, inner walls thickened; micropylar and chalazal haustoria +; mitochondrial coxII.i3 intron 0.

The androecium of both families is very variable in development (Hufford 1990, 1998). It is possible that diplostemony is plesiomorphic, with polystemony derived. The antisepalous androecial triplets sometimes found here are also found in Rosaceae and Zygophyllaceae (Hufford 2001b, see also Ronse Decraene & Smets 1996a). The embryology of the group is poorly studied.

HYDRANGEACEAE Dumortier, nom. cons.   Back to Cornales

Shrubs, vines, or herbs; (plants Al accumulators); kaempferol, myricetin, flavonols +, tanniniferous; (hairs stellate or branched); cork inner cortical or outer pericyclic; (vessel elements with simple perforation plates); true tracheids +; (stomata paracytic); leaves conduplicate or supervolute, bases joined by lines across the stem, (2ndary veins palmate); inflorescence cymose; flowers 4-5(-10)-merous, anthers with basal pit, nectary vascularised, G [(2-)3-5(-12)] to inferior, ovary ribbed, arrangement variable, placentation intrusive parietal, ovules apotropous, integument 5-7(-10 - Hydrangea) cells across, style or styles +, stigma linear to capitate; seed winged or not; endosperm moderate; n = 13-18.

17[list]/190 - divided into two subfamilies, and one subfamily into two tribes. Warm temperate, some species in tropics. [Photo - Flower] [Photos - Collection]

1. Jamesioideae Hufford

Nothing obvious! Leaf buttresses prominent after leaves fall; K valvate, C free, A 10, G (3-)4-5, style branches separate or almost so; endosperm nuclear [Fendlera]; n = 16.

2 (Jamesia, Fendlera)/ca 5. W. North America (Map: from Holmgren & Holmgren 1989).

2. Hydrangeoideae Burnett

Nodes also 5:5, 7(+):7(+); petiole bundles (arcuate [+ inverted bundles]) annular, often with medullary bundles; raphide sacs + (0); stomata variable; (hairs stellate); (filaments winged), cytokinesis simultaneous [Platycrater], pollen grains 2-celled, integument 3-5 cells across.

15/185. Warm temperate, esp. South East Asia and North America, S. to Chile and Malesia (Map: from Hu 1955; Zaikonnikova 1966; McClintock 1957; van Balgooy 1984; Mai 1985; Hong 1993).

2a. Philadelpheae

C imbricate, A initiation as five common primordia, embryo sac ± protruding from the nucellus, style single.

6/130: Philadelphus (65), Deutzia (60). Warm temperate, esp. South East Asia to the Philippines, SW North America, also Central America, one sp. in Europe.

Synonymy: Philadelphaceae Martynov

2b. Hydrangeeae

Raphides +; inflorescence often with conspicuous marginal flowers; C valvate, styles separate; fruits loculicidal, (baccate).

9/65. Warm N. temperate, S. to Chile and Malesia.

For floral morphology of Hydrangeae, see Hufford (2001). The base of the endosperm is lignified.

• Hydrangeaceae are usually rather robust herbs or shrubs with opposite leaves that are joined by a line across the stem. The flowers have free petals that are valvate in bud and at least twice as many stamens as petals; the ovary is more or less inferior.

In a number of taxa the embryo sac more or less protrudes into the micropyle or beyond (Maheshwari 1950; Hufford 2004). The presence of chalazal haustoria needs confirmation.

Philadelphus shows centrifugal androecial development. In Philadelphus, Dichroa and Deutzia the four carpels alternate with the sepals, or there are three carpels with the odd member adaxial; in Hydrangea the odd carpel is abaxial, while in Broussaisia the five carpels are opposite the sepals. Fendlera has nuclear endosperm (Johri et al. 1992). The endocarp of Hydrangea consists of large cells with digitate-interlocking anticlinal walls, as in Curtisia, but not in Cornus (Manchester et al. 2007).

For variation in the position of the carpels when the gynoecium is bicarpellate, see Eichler (1878; also Eckert 1966), for vegetative anatomy, Watari (1939), Styer and Stern (1979 and references) and Gornall et al. (1998), for floral anatomy, see Bensel and Palser (1975c), for seeds, Hufford (1995, 1997) and Nemirovich-Danchenko and Lobova (1998), for iridoids, Frederiksen et al.(1999), for androecial development, Gelius (1967) and Hufford (1998, 2001a), for some embryology, Ao (2008), and for general information, see Hufford (2004). For relationships within the family, see Hufford (1997b), Hufford et al. (2001: support for its monophyly is not overwhelming), and Soltis et al. (1995a), and for a classification of the family, see Hufford et al. (2001).

Synonymy: Hortensiaceae Berchtold & J. S. Presl, Kirengeshomaceae Nakai

LOASACEAE Jussieu, nom. cons.   Back to Cornales

Often coarse herbs (shrubs); myricetin, tannins 0; cork inside pericycle; vessel elements with simple perforation plates; petiole bundles arcuate or annular, with wing bundles; trichomes glochidiate (stinging), often silicified; leaves (spiral; compound; margins lobed), 2ndary veins pinnate-palmate; flowers (4-)5(-7)-merous; K connate, C with three traces, ?valvate, C-A synorganisation, C-A plate formed, filaments terete, tectum striate, G 5 (± superior), opposite sepals, ovules epitropous, tenuinucellate, integument very thick, style hollow, lobed, stigma narrow or clavate; (fruit a cypsela; spirally twisted); (testa with hypodermal layer thickened); endosperm copious to none.

14[list]/265 - five clades below. Mostly American, but also Africa and the Marquesas Islands (map: from Heywood 1978).

1. Eucnide

(C connate), A (adnate to C), centripetal, connate basally; fruit a septicidal capsule; n = (?19-)21.

1/15. S.W. North America. [Photo - Eucnide Flower © J. Reveal]

2. Schismocarpus

A 10, filaments shorter than the anthers, G opposite petals, stigma capitate.

1/1: Schismocarpus pachypus. Mexico.

Loasoideae [Mentzelioideae + Gronovioideae]: G [3-5], when [3], odd member adaxial.

There are some remarkable flowers here!

3. Loasoideae Gilg

Petals cymbiform, clawed, A centripetal and centrifugal, stamens in 5 groups opposite petals, pollen ?not striate, antesepalous staminodes + [outer whorl connate, as scales, inner whorl separate, more elaborated]; n = 6.

Nasa (105: see Weigend " Gottschling 2006 for pollination and revolver flowers). America, but also Africa (Kissenia) and the Marquesas Islands (Plakothira). [Photo - Flower, Flower, Flower, Fruit, Flower.]

The calyx and corolla are shed separately. The clade [Plakothira + Klaprothia + Kissenia] may be sister to all other Loasoideae, but with little support (Hufford et al. 2005), or they may be part of a major polychotomy (see also Weigend et al. 2004). Distribution of [Plakothira + Klaprothia + Kissenia] - Marquesas, South America, Africa...

For more on pollination, see Ackermann and Weigend (2006).

Mentzelioideae + Gronovioideae: loss of C-A synorganisation.

4. Mentzelioideae Gilg

K and C quincuncial, A centripetal, connate basally, (forked staminodes +); n = 7.

Mentzelia (60). [Photo - Flower © S. Wolf.]. America.

The calyx and corolla are shed as a unit.

5. Gronovoioideae M. Roemer

(Hypanthium +), C valvate, petals with a single vascular trace, A 5, opposite sepals (2, three staminodes), anthers bifacial, G 3, with 1 apical crassinucellate [Petalonyx, Gronovia] ovule, funicular obturator +; fruit a cypsela; testa none; endosperm haustoria 0.

[Photo - Gronovia Flower.]. America.

In some species of Petalonyx there is postgenital fusion of the corolla, this forces the stamens outside the corolla.

Synonymy: Cevalliaceae Grisebach, Gronoviaceae Endlicher

• Loasaceae are usually herbs that have barbed or glochidiate silicified and sometimes stinging hairs; at least the first pair of leaves is opposite. The flowers, which usually have separate, spreading petals, numerous, radiating stamens with long filaments, and an inferior ovary, are distinctive.

Strongly supported relationships suggested by Moody and Hufford (2000), Moody et al. (2001), Hufford et al. (2003) and Hufford (2003) are Eucnide [Schismocarpus [Loasoideae [Mentzelioideae + Gronovioideae]]]. Schenk and Hufford (2008) suggest dates for some of the main clade splits in the family.

For the complexities of androecial initiation, see Hufford (1990); antepetalous stamens arise from the flanks of primordia of antisepalous stamens. Hufford (2003) described staminode evolution in detail. The stigma is at least sometimes very long (Loasa triphylla - see Hanf 1935).

Additional information is taken from Vijayaraghavan and Kaur (1967), Thompson and Ernst (1967), Brown and Kaul (1981: floral morphology), Weigend (1996), Hufford (1988, 1989, 1990) and especially Moody and Hufford (2000) and Weigend (2004: general).

HYDROSTACHYACEAE Engler, nom. cons.   Back to Cornales

Annual to perennial submerged rosette herbs; primary root 0, adventitous roots +; kaempferol +, iridoids 0; vessels present, ?type; nodes ?; stomata 0; leaves deeply and complexly divided, surface with small enations, stipule single, intrapetiolar (two, lateral); inflorescence spicate, plants di(mon)oecious; P 0, nectary 0; staminate flowers: A 2, extrose, monothecal, pollen in tetrads, inaperturate; carpellate flowers: G [2], transverse, placentation parietal, many tenuinucellate ovules/carpel, styles separate, filiform; fruit a septicidal capsule; seeds minute, exotestal, outer cell walls much thickened, mucilaginous; endosperm scanty or 0, micropylar haustorium +; n = 10-12.

1[list]/20. C. and S. Africa, Madagascar (Map: from Rauh & Jäger-Zürn 1966b).

• Hydrostachyaceae are submerged, rosette-forming, aquatic herbs with complex leaves bearing enations, stipules that are usually intrapetiolar, dense, spicate inflorescence, and rather small flowers with extrorse anthers and free styles.

The caffeoyl ester chlorogenic acid is found here and in the Loasaceae-Hydrangeaceae clade (Rønsted et al. 2002). Another interpretation of the androecium is that is consists of one tetrasporangiate stamen. Vessels are reported (Jäger-Zürn 1998), but are not described. The integument is about5 cells thick; there seems not to be an endothelium.

For general information, see Erbar and Leins (2004a) and for chemistry, Rønsted et al. (2002).

Grubbiaceae + Curtisiaceae: leaves opposite, bases connected by a ridge; flowers small, one tenuinucellate ovule/carpel, style short; stone walls of sclereidal cells; endosperm copious.

The age of this clade is ca 90 my, suggesting that it is very much a relict in the Cape flora (Warren & Hawkins 2006), although fossil fruits of Curtisia have recently ben identified in the Eocene of southern England (Manchester et al. 2007).

For characters holding these two families together, see in part Xiang et al. (2002).

GRUBBIACEAE Endlicher, nom. cons.   Back to Cornales

Evergreen ericoid shrubs; iridoids 0?; hairs unicellular; cuticle waxes as long narrow platelets; leaf margins revolute; inflorescences axillary, capitate or cone-like; flowers also 6-merous, C 0, A 8, 12, anthers inverted, bisporangiate/monothecal, G [2], transverse, disc hairy, placentation axile at base, becoming free-central, ovule epitropous, integument "thick", style shortly 2-lobed; fruit a syncarp, seed [per fruit proper] 1, coat thin; endosperm ?type, micropylar and chalazal haustoria +; n = ?

1[list]/3. Cape Province, South Africa (Map: from Vester 1940).

• Grubbiaceae are ericoid shrubs with capitate or cone-like inflorescences lacking radiating inflorescence bracts; its fruits are closely aggregated (cf. Bruniaceae).

The family is poorly known. There is support for a sister group relationship to Curtisiaceae (e.g. Fan & Xiang 2001); Xiang et al. (2002) suggested that the two might be combined, but they are kept separate here because they are rather different in appearance. The inversion of the anther is very comprehensive in Grubbiaceae, and for some (e.g. Fagerlind 1947b) this has suggested relationships with Ericaceae. Carlquist (1978a) found Grubbiaceae to be anatomically identical to Bruniaceae (near Asterales here), cf. also Geissolomataceae (Crossosomatales).

Some information is taken from Schnizlein (1843-1870: fam. 18 - carpel orientation), Fagerlind (1948b: embryology), Dahlgren and van Wyk (1988: general) and Kubitzki (2004b: general).

Synonymy: Ophiraceae Arnott

CURTISIACEAE Takhtajan   Back to Cornales

Evergreen trees; route I secoiridoids +, ?ellagic acid; ?cork; ?nodes; petiole bundle annular, with medullary strands; leaves ± flat, margins serrate; inflorescence terminal; K small, stamens = and opposite sepals, pollen with H-shaped endapertures, G [2-4], stigma 4 lobed, gynoecium with axial/central vascular bundles; fruit 4-seeded; ?endosperm haustoria, embryo long; n = 13.

1/2. Southern Africa (Map: from Palgrave 2002). [Photo - Fruit]

Manchester et al. (2007) recognised fruits of Curtisia from the Eocene of southern England; the fossils were priginally described under Epacridaceae (= Ericaceae - Styphelioideae)!

Takhtajan (1997) described the hairs of the branchlets, petioles and inflorescences of Curtisia as being stellate (they are curled). The "plications" (Cullen 1978) in the young leaves are in fact only prominent veins. Curtisia is embryologically unknown, but it lacks transseptal bundles, having the "normal" central bundles.

For general information, see Kubitzki (2004b).