LIGNOPHYTA

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

EXTANT SEED PLANTS/SPERMATOPHYTA

Plant woody, evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins derived from (some) sinapyl and particularly coniferyl alcohols, thus containing p-hydroxyphenyl and guaiacyl lignin units, (lignins derived from p-coumaryl alcohol, i.e. S [syringyl] lignin units); true roots present, apex multicellular, xylem exarch, and branching endogenous; arbuscular mycorrhizae +; shoot apical meristem multicellular, interface specific plasmodesmatal network; stem with ectophloic eustele, endodermis 0, xylem endarch, branching exogenous; vascular tissue in t.s. discontinuous by interfascicular regions; vascular cambium + [xylem ("wood") differentiating internally, phloem externally]; wood homoxylous, tracheids and rays alone, tracheid/tracheid pits circular, bordered; mature sieve tube/cell lacking functioning nucleus, plastids with starch grains; phloem fibres +; stem cork cambium superficial, root cork cambium deep seated; leaves with single trace from sympodium ["nodes 1:1"]; stomata ?; leaf vascular bundles collateral; leaves megaphyllous [determinancy evolved first, then ad/abaxial symmetry], spiral, simple, lamina with vein density up to 5 mm/mm² [mean for all non-angiosperms 1.8]; axillary buds associated with at most some leaves; prophylls [including bracteoles] two, lateral; plant heterosporous, sporangia eusporangiate, on sporophylls, sporophylls aggregated in indeterminate cones/strobili; true pollen [microspores, i.e. no distal pore for release of gametes] +, grains mono[ana]sulcate, exine and intine homogeneous; ovules unitegmic, crassinucellate, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development first endo- then exosporic, tube developing from distal end of grain, to ca 2 mm from receptive surface to egg, gametes two, developing after pollination, with cell walls, with many flagellae; female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large", first cell wall of zygote transverse, embryo straight, endoscopic [suspensor +], short-minute, with morphological dormancy, white, cotyledons 2; plastid transmission maternal; two copies of LEAFY gene, PHY gene duplications [three - [BP [A/N + C/O]] - copies], nrDNA with 5.8S and 5S rDNA in separate clusters; mitochondrial nad1 intron 2 and coxIIi3 intron and trans-spliced introns present.

MAGNOLIOPHYTA

Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, [cyanogenesis in ANITA grade?], S [syringyl] lignin units common, positive Maüle reaction [syringyl:guaiacyl ratio more than 2-2.5:1], and hemicelluloses as xyloglucans; root apical meristem intermediate-open; root vascular tissue oligarch [di- to pentarch], lateral roots arise opposite or immediately to the side of [when diarch] xylem poles; origin of epidermis with no clear pattern [probably from inner layer of root cap], trichoblasts [differentiated root hair-forming cells] 0; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, with gelatinous fibres; starch grains simple; primary cell wall mostly with pectic polysaccharides, poor in mannans; tracheid:tracheid [end wall] plates with scalariform pitting, wood parenchyma +; sieve tubes enucleate, sieve plate with pores (0.1-)0.5-10< µm across, cytoplasm with P-proteins, cytoplasm not occluding pores of sieve plate, companion cells from same mother cell that gave rise to the sieve tube; sugar transport in phloem passive; nodes unilacunar [1:?]; stomata with ends of guard cells level with pore, paracytic, outer stomatal ledges producing vestibule; leaves petiolate, lamina [formed from the primordial leaf apex], development of venation acropetal, 2ndary veins pinnate, fine venation reticulate, veins (1.7-)4.1(-5.7) mm/mm², endings free; most/all leaves with axillary buds; flowers perfect, pedicellate, polysymmetric, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P not sharply differentiated, with a single trace, outer members not enclosing the rest of the bud, often smaller than inner members; A many, filament not sharply distinguished from anther, stout, broad, with a single trace, anther introrse, tetrasporangiate, sporangia in two groups of two [dithecal], ± embedded in the filament, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally by action of hypodermal endothecium, endothecial cells elongated at right angles to long axis of anther; tapetum glandular, binucleate; microspore mother cells in a block, microsporogenesis successive, walls developing by centripetal furrowing; pollen subspherical, tectum continuous or microperforate, ektexine columellar, endexine thin, compact, lamellate only in the apertural regions; nectary 0; G free, several, ascidiate, with postgenital occlusion by secretion, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, dry [not secretory]; ovules few [?1]/carpel, marginal, anatropous, bitegmic, micropyle endostomal, outer integument 2-3 cells across, often largely subdermal in origin, inner integument 2-3 cells across, often dermal in origin, parietal tissue 1-3 cells across [crassinucellate], nucellar cap?; megasporocyte single, hypodermal, megaspore tetrad linear, functional megaspore chalazal, lacking sporopollenin and cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; P deciduous in fruit; seed exotestal; pollen binucleate at dispersal, trinucleate eventually, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing at 80-600 µm/hour, with pectic outer wall, callose inner wall and callose plugs, growing between cells, penetration of ovules via micropyle [porogamous] within ca 18 hours, distance to first ovule 1.1.-2.1 mm, tube moves between nucellar cells; double fertilisation +, endosperm diploid, cellular [micropylar and chalazal domains develop diffently, first division oblique, micropylar end initially with a single large cell, divisions uniseriate, chalazal cell smaller, divisions in several planes], copious, oily and/or proteinaceous, embryo cellular ab initio, minute; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)_n]; whole genome duplication, ndhB gene 21 codons enlarged at the 5' end, single copy of LEAFY and RPB2 gene, knox genes extensively duplicated [A1-A4], AP1/FUL gene, paleo AP3 and PI genes [paralogous B-class genes] +, with "DEAER" motif, SEP3/LOFSEP and three copies of the PHY gene, [PHYB [PHYA + PHYC]].

Evolution. Possible apomorphies for flowering plants are in bold. Note that the actual level to which many of these features, particularly the more cryptic ones, should be assigned is unclear. This is because some taxa basal to the [magnoliid + monocot + eudicot] group have been surprisingly little studied, there is considerable homoplasy as well as variation within and between families of the ANITA grade in particular for several of these characters, and also because details of relationships among gymnosperms will affect the level at which some of these characters are pegged. For example, if reticulate-perforate pollen is optimized to the next node on the tree (see Friis et al. 2009 for a discussion), it effectively makes the pollen morphology of the common ancestor of all angiosperms ambiguous... For other features such as details of sugar transport in the phloem, their placement on the tree is frankly speculative. Finally, for features such as parietal tissue/a nucellus only one (Nymphaeales) to three cells thick above the embryo sac and a stylar canal lacking an epidermal layer, although plesiomorphous for basal grade angiosperms (Williams 2009), I am unsure where on the tree a thicker nucellus and a stylar epidermal layer are acquired.

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

[AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: ethereal oils in spherical idioblasts [lamina and P ± pellucid-punctate]; tension wood 0; tectum reticulate-perforate [here?], nucellar cap + [character lost where in eudicots?]; 12BP [4 amino acids] deletion in P1 gene.

[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]] / MESANGIOSPERMAE: benzylisoquinoline alkaloids +; outer epidermal walls of root elongation zone with cellulose fibrils oriented transverse to root axis; P more or less whorled, 3-merous [possible position]; carpels plicate; embryo sac bipolar, 8 nucleate, antipodal cells persisting; endosperm triploid; ?germination.  Back to Main Tree

Evolution. Divergence & Distribution. Bell et al. (2010: note, Chloranthaceae sister to Magnoliidae + everything else, but not monocots) suggest ages of (140-)140(-128) or (135-)127(-119) million years depending on the method used, while Davies et al. (2011: 95% credibility intervals) suggested a somewhat older age of (179-)152(-133) million years. Some other age estimates are substantially older, ranging from (200-)174(-153) million years (with eudicot calibration) to (210-)184(-160) million years (without: Smith et al. 2010).

Chemistry, Morphology, etc. For the distribution of isoquinoline alkaloids, alternatively known as 1-benzyltetrahydroisoquinoline alkaloids, 1-btiq alkaloids, see Waterman 1999, 2007). The betalains of core Caryophyllales have biosynthetic similarities with these alkaloids. For the orientation of cellulose fibrils in the outer epidermal walls of root elongation zone, see Kerstens and Verbelen (2002); I do not know what happens in the ANITA grade and in gymnosperms, and magnoliids and eudicots are very poorly sampled. This is perhaps the best place to put triploid endosperm on the tree; the other would be as a synapomorphy for all angiosperms, but in that case it would subsequently be lost twice, or lost once and then regained.

Phylogeny. Relationships between the lineages immediately above the basal pectinations in the main tree, the ANITA grade (Amborellales, Nymphaeales and Austrobaileyales here), have only recently been clarified. The topology of the main tree in this area thus differs somewhat from that in A.P.G. II (2003). The optimisation of benzylisoquinoline alkaloids on the tree is unclear. They appear to occur in Chloranthaceae, the magnoliids, and eudicots, so if there is a clade [Chloranthaceae + magnoliids] [monocots [Ceratophyllaceae + eudicots]], as is provisionally recognized in this site, they may be best optimised here. For further information, see especially the discussion immediately preceding the Magnoliales, i.e. the magnoliid clade, eudicots, and monocots are the other clades involved.

[CHLORANTHALES [[MAGNOLIALES + LAURALES] [CANELLALES + PIPERALES]]]: sesquiterpenes +; seed endotestal.

Evolution. Divergence & Distribution. Moore et al. (2010: 95% highest posterior density) estimate an age of (141-)136(-129) million years for this node; Davies et al. (2011: 95% credibility intervals) suggested a somewhat older age of (176-)149(-128) million years.

Although Soltis et al. (2008) suggest ages for a number of branching points in this clade, they are based on the topology [monocots [Chloranthaceae, magnoliids [Ceratophyllaceae + eudicots]]]. Doyle and Endress (2010) suggest that the Pennipollis plant, from ca 120-115 million years ago in Portugal and originally linked to the monocots (Petersen et al. 2000b), is sister to Chloranthaceae, but they consider that family to be sister to all angiosperms apart from the ANITA grade.

The character, "endotesta palisade, crystaliferous", could perhaps be placed at this node.

CHLORANTHALES Martius  Main Tree, Synapomorphies.

Branching from the current flush; neolignans ?+; nodes often swollen; leaves opposite, joined by sheath, lamina margins toothed, teeth with lateral vein and others [hydathodal]; stipules +; flowers very small, monosymmetric by reduction, parts whorled; P 0, A 1, abaxial; G 1, ± inferior, ascidiate, postgenital fusion by secretion; ovule 1/carpel, apical, pendulous, straight; antipodal cells proliferating; fruit fleshy; endotesta palisade, lignified, crystalliferous; (endosperm starchy, grains clustered). - 1 family, 4 genera, 75 species.

Includes Chloranthaceae.

Synonymy: Chloranthineae Thorne & Reveal - Chloranthanae Doweld - Chloranthidae C. Y. Wu

CHLORANTHACEAE Sims, nom. cons.   Back to Chloranthales

Evergreen; wood storied; (vessels 0); primary stem with vascular cylinder; rays 6-10-seriate; nodes 1:1, 1:2, or ± 3:3, 2 traces from the central or all gaps, (+ split laterals); (sclereids - Hedyosmum); cuticle wax crystalloids 0; stomata variable, laterocytic, etc.; branching from current flush; lamina vernation conduplicate [Chloranthus], teeth with clear persistent swollen cap into which proceed higher order veins as well as secondaries or tertiaries; stipules small, paired, interpetiolar, usually on rim of sheath; (plants dioecious); flowers sessile; staminate flowers: A ± latrorse, lobed, or connective produced or not; pistillode 0; carpellate flowers: (P + - Hedyosmum, ± connate); staminode 0; stigma ± expanded or not, dry ?or wet; ovules with outer integument 4-8 (2 - Ascarina) cells across, inner integument (3-)7-10 cells across, (micropyle bistomal), parietal tissue 6-8 cells across, nucellar cap +/0; fruit baccate or drupaceous, (bracts accrescent and succulent), (P persistent); coat ± tanniniferous, (mesotesta lignified - Chloranthus), tegmen ± crushed, (exo- and mesotegmen fibrous), endotegmen initially subpalisade; n = 8, 14, 15, chromosomes 1-4(-10: Hedyosmum) µm long.

4[list]/75: Hedyosmum (45). Tropics and subtropics, not Africa (Madagascar - Ascarina only) (map: from Verdcourt 1986; Todzia 1988). [Photo - Leaf, Flower.]

• Chloranthaceae are aromatic plants that may be recognised by their opposite, serrate leaves with more or less sheathing stipules and often strongly swollen nodes that may collapse on drying. The flowers are very small and are often borne on branched inflorescences; the fruits are fleshy. The wood is soft.

Evolution. Divergence & Distribution. Estimates of the time of divergence of stem Chloranthaceae are (168-)131(-126) million years before present, however, estimates of the age of crown group diversification are much more recent, being mostly within the last 60-29 million years, and that of the genera still more recent (Zhang & Renner 2003b; Soltis et al. 2008). However, Antonelli and Sanmartín (2011) suggested ages of only (112-)111(-110) or thereabouts for the crown group diversification, with all genera having separated by ca 90 million years (from fossil data). Diversification within Hedyosmum was again much later and could be dated to (57.1-)43.3(-30.1) or (43-)35.6-(25.9) million years ago depending on the method used, and was in part associated with the Andean uplift, although the family as a whole shows a pattern of gradual extinction over time (Antonelli & Sanmartín 2011). Zhang et al. (2011) provide another series of age estimates, some of which are dramatically older than the others depending on their calibration and the analytical methods used.