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.

[SABIACEAE + PROTEALES] [TROCHODENDRALES [BUXALES + CORE EUDICOTS]]]: (axial/receptacular nectary +).

Evolution. Estimates of the age of divergence within this clade (but as [Proteales [Sabiales [Buxales [Trochodendrales....]) range from (138-)125, 121(-110) million years (see Bell et al. 2010 for details), while Magallón and Castillo (2009) suggest ages of ca 122.8 and 123.6 (relaxed and constrained penalized likelihood ages) million years for the clade.

Chemistry, Morphology, etc. For the distinction between gynoecial (supposedly asterids only) and receptacular nectaries, see Smets (1988) and Smets et al. (2003); for a general survey of nectaries, see Bernadello (2007).

Phylogeny. The position of Sabiaceae has been unclear. Worberg et al. (2007: Ophiocaryon not included) found Sabiaceae to be sister to all other [eudicots minus Ranunculaceae], although with little more than 80% jacknife support; this position is temporarily adopted here. For further discussion see the Ranuculales page, and for an updated discussion on Sabiaceae and its relationships, see the Proteales page - I think that is where Sabiaceae will end up.

SABIALES Takhtajan  Main Tree, Synapomorphies.

P = K + C, pollen colporate, nectary a thin ± lobed disc; G connate, 1 or 2 pendulous campylotropous ovules/carpel, micropyle 0; seed with condyle [placental intrusion]; endosperm helobial, embryo long, curved. - 1 family, 3 genera, 100 species.

Includes Sabiaceae.

Synonymy: Meliosmales C. Y. Wu et al.

SABIACEAE Blume, nom. cons.   Back to Main Tree

Evergreen (deciduous) trees or lianes; pentacyclic triterpenoids +, tanniniferous, benzylisoquinoline alkaloids?; vessel elements with simple to scalariform perforation plates, bars few (-30); wood with broad rays (0 - Sabia), (true tracheids +; pits vestured - Meliosma); secondary phloem with broad or flaring rays; nodes complex unilacunar [Meliosma]; (sieve tube plastids also with protein crystalloids); cuticle wax crystalloids 0; stomata also paracytic; buds perulate or not; leaves spiral or two-ranked, simple to odd-pinnately compound, conduplicate [Meliosma], teeth ± spiny or 0; flowers poly- or obliquely monosymmetric, (3-)5-merous, K C A opposite each other, latter basally adnate to C, (2 A fertile, with 2 basal processes and opposing C small, 2-3 A staminodial - Meliosma, Ophiocaryon); A 5 (Sabia), disporangiate [?Ophioocaryon], dehiscence transverse or valvular; G [2-3], completely closed (also secretory canal), when 2, oblique or median, ovules apotropous, (Sabia - unitegmic, integument 6 cells across), styluli (marginal - Ophiocaryon) short, stigmas punctate, wet; fruit a (bilobed) ± drupelet to ± dry, dehiscent, (styluli excentric); seed coat ?; chalazal endosperm haustoria +, (embryo ± spiral or coiled), cotyledons usually folded; n = 12, 16.

3[list]/100: Meliosma (70). South East Asia to Malesia, tropical America (map: from van Beusekom 1973; Sinimbu, pers. comm. Rafael Sühs). [Photo - Flower] [Photo - Fruit]

• Sabiaceae are evergreen trees or lianes that may be recognised by the brochidodromous venation of their leaves or leaflets, their small flowers with the perianth whorls and stamens all opposite, and the more or less flattened and distinctly curved drupes; the surface of the latter is often distinctly venose.

Evolution. Fossils of Sabiaceae are known from the Cretaceous-Cenomanian (ca 98 million years before present, Insitiocarpus, c.f. Meliosma) and -Turonian (Sabia) of Europe (Knobloch & Mai 1986). Anderson et al. (2005) date stem group Sabiaceae to 122-118 million years before present, crown group Sabiaceae 119-91 million years before present, and Magallón and Castillo (2009: Sabiaceae part od the eudicot pectination) offer the figure of ca 123.2 million years for the stem age.

Sabiaceae are distinctive among members of the eudicot grade in that the perianth is differentiated into a calyx and corolla (Drinnan et al. 1994; Hoot et al. 1999) and there is a nectary that appears to be axial/receptacular. Meliosma has explosively dehiscent anthers that are held under tension by the complex staminodes, but there is also a kind of secondary pollination presentation in which pollen collects on the broad connective between the anthers sacs (Ronse De Craene & Wanntorp 2008 for discussion).

Chemistry, Morphology, etc. There have been arguments over the interpretation of the flower of Meliosma, especially of the nature of the perianth members; two sepals are smaller than the others and have been called bracteoles. According to Baillon (1874), the two carpels of Sabia are median; Wanntorp and Ronse de Craene (2007) illustrate those of Meliosma as being more or less collateral. Warburg (1896) drew the two carpels of Meliosma as being oblique to the vertical axis of the flowers, but median to the plane between the two bracteoles; van Beusekom and van der Water (1989) show the carpels as being oblique both to the vertical axis and to the plane between the bracteoles, and the flower could be called obliquely monosymmetric (for a careful study, see Wanntorp & Ronse de Craene 2007).

In Meliosma the integument does not grow over the apical part of the nucellus so there is no micropyle. Ophiocaryon paradoxum has a coiled embryo; it is known as the snake nut. For chemistry, see Hegnauer (1973, 1990), and for a general account, see Kubitzki (2006b).

Classification. For a revision of Sabia, see van de Water (1980).

Synonymy: Meliosmaceae Endlicher, Wellingtoniaceae Meisner