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.

ROSIDS: (nectary receptacular); (mucilage cells with thickened inner periclinal walls and distinct cytoplasm); embryo long; genome duplication; chloroplast infA gene defunct, mitochondrial coxII.i3 intron 0.

MALVIDAE = [GERANIALES + MYRTALES] [CROSSOSOMATALES [PICRAMNIALES [SAPINDALES [HUERTEALES [MALVALES + BRASSICALES]]]]]: ?

[CROSSOSOMATALES [PICRAMNIALES [SAPINDALES [HUERTEALES [MALVALES + BRASSICALES]]]]]: ?

PICRAMNIALES [SAPINDALES [HUERTEALES [MALVALES + BRASSICALES]]]: ovules 2/carpel, apical.

Chemistry, Morphology, etc. The position of the character of ovule number on the tree is unclear. However, taxa with one or two usually apical ovules/carpel are common in the rosid II clade.

Phylogeny. See the Dilleniales and the Saxifragales pages for further discussion on the relationships of the malvids in general and of Picramniales in particular.

PICRAMNIALES Doweld  Main Tree, Synapomorphies.

C₁₈ acetylenic tariric acid, petroselenic acid [both in seed oils], anthraquinones, anthracenone moieties linked to C₅-sugar derivatives +; vessel elements with simple perforations; staminate flowers: stamens = and opposite petals; ?seed coat; ?endosperm, ?embryo. - 1 family, 2 genera, 46 species.

Includes Picramniaceae.

Synonymy: Picramniineae Shipunov

PICRAMNIACEAE Fernando & Quinn

Trees; bark bitter or very bitter; leaves spiral, odd-pinnate, leaflets often ± alternate, vernation conduplicate, extrafloral nectaries on abaxial surface, stipules 0; plant dioecious, inflorescence racemose; flowers 3-5(-6)-merous, small, K connate basally (free); staminate flowers: pollen?; nectary +; pistillode minute; carpellate flowers: staminodes [?nectariferous] +; G [2-3], styles recurved, pointed; ovule with ?bistomal micropyle; endosperm ?development; n = ?

3[list]/49. Neotropical.

1. Picramnia

Ovules epitropous; fruit a berry; seed coat ca 6 cells across, vascularized, unlignified, or two subepidermal layers lignified, inner layers crushed; embryo minute.

1/41. S.E. USA, Central and South America, Caribbean (map: from Pirani 1990). [Photo - Fruit]

2. Nothotalisia

Anatomy?; staminate flower: androgynophore +; A extrorse, connective prolonged; nectary 0; fruit a berry; seed coat, etc.?

1/3. Panama and NW South America (map: green in the map below, from Thomas 2011).

3. Alvaradoa

Vascular tracheids +; staminate flowers: C usu. 0; carpellate flowers: staminodes opposite sepals; only 1 G fertile; ovules apotropous, basal; fruit a samaroid capsule; exotesta resinous, endotegmen as a resinous membrane; endosperm 0, cotyledons large.

1/5. Florida, Central America, Bahama, esp. the Greater Antilles, Bolivia to Argentina (map: red, from Thomas 1990). [Photo - Fruit]

• Picramniaceae are often rather small trees with bitter-tasting bark and spirally-arranged, compound leaves; the leaflets alternate along the rachis. The small flowers are born in a raceme, and the stamens are equal to and opposite the petals.

Evolution. Divergence & Distribution. Magallón and Castillo (2009) estimated ages of ca 107.9 and 108.4 million years for relaxed and constrained penalized likelihood datings for the age this clade, although it was placed as part of a basal polytomy in the malvid clade.

Chemistry, Morphology, etc. The bitter taste in the bark is probably caused by the presence of sugar-linked anthracenone derivatives (Jacobs 2003). Indeed, Jacobs (2003) emphasizes the distinctive nature of their secondary metabolites, these anthracenone moieties linked to C₅-sugar derivatives apparently being unknown in any other plants and the C₁₈acetylenic acid, tariric acid, is also unknown from other flowering plants (see also Bohlmann et al. 1973; Badami & Patil 1981). For some chemistry of Alvaradoa, see Villatoro et al. (1974).

The family is very poorly known, particularly the recently described Nothotalisia; I have seen only Picramnia in the field. Xylem parenchyma is rather scanty to absent. fibre tracheids dominate, but Alvaradoideae commonly have vascular tracheids (Webber 1936). Picramnia may have unilacunar nodes with three or more traces; the hairs are unicellular and have distinctive golden contents (M. Ogburn, pers. comm.).

For general information, see Fernando and Quinn (1995) and Kubitzki (2006b), for Nothotalisia, see Thomas (2011), and for chemistry, see Hegnauer (1973, 1990) and Stuhlfauth et al. (1985), both as Simaroubaceae, and especially Jacobs (2003). Rao (1970) briefly mentions the seed coat of Alvaradoa. Additional data are taken from seeds of Alvaradoa (Núñez et al. 83), Picramna sellowiana (Vásquez & Jaramillo 11419) and P. latifolia (Aguilar 5020).

Classification. Prior to version 10 of this site I had two subfamilies for the (then) two genera in Picramniaceae; even although there are now three genera in the family, a suprageneric classification within it seems altogether too much.

Previous Relationships. Picramniaceae were placed between Rosid I, which includes Surianaceae and Irvingiaceae (ex Simaroubaceae), and Rosid II, which includes Simaroubaceae themselves, by Fernando et al. (1995), but in the past they have usually been placed within Simaroubaceae (e.g. Cronquist 1981; Takhtajan 1997) with which they agree in their bitter bark, compound leaves and small flowers.