EMBRYOPSIDA Pirani & Prado (crown group)
Gametophyte dominant, independent, multicellular, thalloid, with single-celled apical meristem, showing gravitropism; flavonoids + [absorbtion of UV radiation]; protoplasm dessication tolerant [plant poikilohydric]; cuticle +; cell walls with (1->4)-ß-D-glucans [xyloglucans], lignin +; rhizoids unicellular; several chloroplasts per cell; glycolate metabolism in leaf peroxisomes [glyoxysomes]; centrioles in vegetative cells 0, metaphase spindle anastral, predictive preprophase band of microtubules, phragmoplast + [cell wall deposition spreading from around the spindle fibres], plasmodesmata +; antheridia and archegonia jacketed, stalked; spermatogenous cells monoplastidic, centrioles develop de novo, associated with basal bodies of flagellae, multilayered structure +, proximal end of basal bodies lacking symmetry, stellate pattern associated with doublet tubules of transition zone; spermatozoids with a left-handed coil; male gametes with 2 lateral flagellae; oogamy; diploid embryo initially surrounded by haploid gametophytic tissue, plane of first division horizontal [with respect to long axis of archegonium/embryo sac], suspensor/foot +, cell walls with nacreous thickenings; sporophyte multicellular, sporangium +, single, with polar transport of auxin, dehiscence longitudinal; meiosis sporic, monoplastidic, microtubule organizing centre associated with plastid, cytokinesis simultaneous, preceding nuclear division, sporocytes 4-lobed, with a quadripolar microtubule system; spores in tetrads, sporopollenin in the spore wall, wall with several trilamellar layers [white-line centred layers, i.e. walls multilamellate]; spores trilete [?level]; close association between the trnLUAA and trnFGAA genes on the chloroplast genome.
Note that many of the bolded characters in the characterization above are apomorphies in the streptophyte clade along the lineage leading to the embryophytes rather than being apomorphies of the embryophytes.
Abscisic acid, ?D-methionine +; sporangium with seta, seta developing from basal meristem [between epibasal and hypobasal cells], sporangial columella + [developing from endothecial cells]; stomata +, anomocytic, cell lineage that produces them with symmetric divisions [perigenous]; underlying similarities in the development of conducting tissue and in rhizoids/root hairs; polar transport of auxins and class 1 KNOX genes expressed in the sporangium alone; MIKC, MI*K*C* and class 1 and 2 KNOX genes, post-transcriptional editing of chloroplast genes; gain of three group II mitochondrial introns.
[Hornworts + Polysporangiophyta]: archegonia embedded/sunken in the gametophyte; sporophyte long-lived, chlorophyllous, nutritionally largely independent of the gametophyte; sporophyte-gametophyte junction interdigitate, sporophyte cells showing rhizoid-like behaviour; spores trilete.
Sporophyte well developed, branched, free living, sporangia several; spore walls not multilamellate [?here]; apical meristem +.
EXTANT TRACHEOPHYTA / VASCULAR PLANTS
Photosynthetic red light response; water content of protoplasm relatively stable [plant homoiohydric]; control of leaf hydration passive; (condensed or nonhydrolyzable tannins/proanthocyanidins +); vascular tissue +, sieve cells + [nucleus degenerating], tracheids +, in both protoxylem and metaxylem; endodermis +; root xylem exarch [development centripetal]; stem with an apical cell; branching dichotomous; leaves spirally arranged, blades with mean venation density 1.8 mm/mm2 [to 5 mm/mm2]; sporangia adaxial on the sporophyll, sporangia derived from periclinal divisions of several epidermal cells, wall multilayered [eusporangium]; columella 0; stellate pattern split between doublet and triplet regions of transition zone; placenta with single layer of transfer cells in both sporophytic and gametophytic generations, embryo with roots arising lateral to the main axis [plant homorhizic].[MONILOPHYTA + LIGNOPHYTA]
Branching ± monopodial; lateral roots +, endogenous, root apex multicellular, root cap +; tracheids with scalariform-bordered pits; leaves with apical/marginal growth, venation development basipetal, growth determinate; sporangia borne in pairs and grouped in terminal trusses, dehiscence longitudinal, a single slit; cells polyplastidic, microtubule organizing centres not associated with plastids, diffuse, perinuclear; male gametes multiflagellate, basal bodies staggered, blepharoplasts paired; chloroplast long single copy ca 30kb inversion [from psbM to ycf2].
Plant woody; lateral root origin from the pericycle; shoot apical meristem multicellular; branching lateral, meristems axillary; cork cambium + [producing cork abaxially], vascular cambium bifacial [producing phloem abaxially and xylem adaxially].
EXTANT SEED PLANTS/SPERMATOPHYTA
Plant 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 [hence with p-hydroxyphenyl and guaiacyl lignin units, so no Maüle reaction]; root with xylem and phloem originating on alternate radii, vascular tissue not medullated, cork cambium deep seated; arbuscular mycorrhizae +; shoot apical meristem interface specific plasmodesmatal network; stem with vascular cylinder around central pith [eustele], phloem abaxial [ectophloic], endodermis 0, xylem endarch [development centrifugal]; wood homoxylous, tracheids and rays alone, tracheid/tracheid pits circular, bordered; mature sieve tube/cell lacking functioning nucleus, sieve tube plastids with starch grains; phloem fibres +; stem cork cambium superficial; branches exogenous; leaves with single trace from vascular sympodium [nodes 1:1]; stomatal pore with active opening in response to leaf hydration, control by abscisic acid, metabolic regulation of water use efficiency, etc.; leaves with petiole and lamina, development basipetal, blade simple; axillary buds +, not associated with all leaves; prophylls two, lateral; plant heterosporous, sporangia borne on sporophylls; microsporophylls aggregated in indeterminate cones/strobili; true pollen +, grains mono[ana]sulcate, exine and intine homogeneous; ovules unitegmic, parietal tissue 2+ cells across, megaspore tetrad linear, functional megaspore single, chalazal, lacking sporopollenin, megasporangium indehiscent; pollen grains landing on ovule; male gametophyte development first endo- then exosporic, tube developing from distal end of grain, gametes two, developing after pollination, with cell walls; female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large" [ca 8 mm3], but not much bigger than ovule, with morphological dormancy; embryo cellular ab initio, endoscopic, plane of first cleavage of zygote transverse, suspensor +, short-minute, embryo axis straight, so shoot and root at opposite ends [plant allorhizic], white, cotyledons 2; plastid transmission maternal; ycf2 gene in inverted repeat, whole nuclear genome duplication [zeta duplication], 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.
Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, 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, exodermis +; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, associated gelatinous fibres [g-fibres] with innermost layer of secondary cell wall rich in cellulose and poor in lignin; 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 cell and sieve tube from same mother cell; sugar transport in phloem passive; nodes 1:?; stomata brachyparacytic [ends of subsidiary cells level with ends of pore], outer stomatal ledges producing vestibule, reduction in stomatal conductance to increasing CO2 concentration; lamina formed from the primordial leaf apex, margins toothed, development of venation acropetal, overall growth ± diffuse, venation hierarchical-reticulate, secondary veins pinnate, veins (1.7-)4.1(-5.7) mm/mm2, endings free; most/all leaves with axillary buds; flowers perfect, pedicellate, ± haplomorphic, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P +, members each with a single trace, outer members not sharply differentiated from the others, not enclosing the floral bud; 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, endothecium +, endothecial cells elongated at right angles to long axis of anther; tapetum glandular, cells binucleate; microspore mother cells in a block, microsporogenesis successive, walls developing by centripetal furrowing; pollen subspherical, tectum continuous or microperforate, ektexine columellate, endexine thin, compact, lamellate only in the apertural regions; nectary 0; carpels present, superior, free, several, ascidiate, with postgenital occlusion by secretion, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, carinal, 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, functional megaspore lacking cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; supra-stylar extra-gynoecial compitum +; ovule not increasing in size between pollination and fertilization; pollen grains landing on stigma, bicellular at dispersal, mature male gametophyte tricellular, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing between cells, growth rate 20-20,000 µm/hour, outer wall pectic, inner wall callose, with callose plugs, penetration of ovules via micropyle [porogamous], whole process takes ca 18 hours, distance to first ovule 1.1-2.1 mm; male gametes lacking cell walls, flagellae 0, double fertilization +, ovules aborting unless fertilized; P deciduous in fruit; seed exotestal, becoming much larger than ovule at time of fertilization; endosperm diploid, cellular [micropylar and chalazal domains develop differently, 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; embryogenesis cellular; dark reversal Pfr -> Pr; Arabidopsis-type telomeres [(TTTAGGG)n]; 2C genome size 1-8.2 pg [1 pg = 109 base pairs], whole nuclear genome duplication [epsilon duplication]; protoplasm dessication tolerant [plant poikilohydric]; 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]].
[NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]]: wood fibres +; axial parenchyma diffuse or diffuse-in-aggregates; pollen monosulcate [anasulcate], tectum reticulate-perforate [here?]; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.
[AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]: vessel elements with scalariform perforation plates in primary xylem; essential oils in specialized cells [lamina and P ± pellucid-punctate]; tension wood +; tectum reticulate; anther wall with outer secondary parietal cell layer dividing; carpels plicate; nucellar cap + [character lost where in eudicots?]; 12BP [4 amino acids] deletion in P1 gene.
[[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]] / MESANGIOSPERMAE: benzylisoquinoline alkaloids +; sesquiterpene synthase subfamily a [TPS-a] [?level], polyacetate derived anthraquinones + [?level]; outer epidermal walls of root elongation zone with cellulose fibrils oriented transverse to root axis; P more or less whorled, 3-merous [possible position]; pollen tube growth intra-gynoecial; embryo sac bipolar, 8 nucleate, antipodal cells persisting; endosperm triploid.
[CHLORANTHALES [[MAGNOLIALES + LAURALES] [CANELLALES + PIPERALES]]]: sesquiterpenes +; seed endotestal.
[[MAGNOLIALES + LAURALES] [CANELLALES + PIPERALES]] / MAGNOLIIDS / MAGNOLIANAE Takhtajan: (neolignans +); vessels solitary and in radial multiples, (with simple perforation plates in primary xylem); (sieve tube plastids with polygonal protein crystals); lamina margins entire; A many, spiral [possible position here], extrorse; G connate by congenital intercarpellary fusion [possible position]; ovules with hypostase, nucellar cap +, raphal bundle branches at the chalaza; antipodal cells soon die.
[[CANELLALES + PIPERALES]: flavonols, aporphine alkaloids +; nodes 3:3; G whorled.
Age. Magallón and Castillo (2009: note topology) offer estimates of ca 201 and 128 m.y. for this node; an age suggested by Magallón et al. (2013) is around 137.9 m.y..
Evolution. Divergence & Distribution. Sokoloff et al. (2013d) optimised congenital intercarpellary fusion to this node.
Chemistry, Morphology, etc. Doyle (2007) noted that the venation of members of this group was poorly differentiated and of low rank.
CANELLALES Cronquist Main Tree.
Neolignans?, drimane-type sesquiterpenes +; indumentum 0; primary stem with continuous vascular cylinder; sieve tube plastids with starch and protein crystalloids and/or fibres; petiole bundle(s) arcuate; leaf cuticle waxes as tubules, nonacosan-10-ol the main wax; foliar sclereids +, branched; branching from previous innovation; flowers of moderate size; K and C distinct; fruit indehiscent, fleshy. - 2 families, 9-13 genera, 75-105 species.
Age. Magallón and Castillo (2009) offer estimates of around 128 and 125 m.y. for crown group Canellales, Wikström et al. (2001) ages of (111-)105, 99(-93) m.y., Bell et al. (2010: note topology) ages of (111-)80, 77(-50) m.y., Xue et al. 2012) an age of ca 101.3 m.y., and Magallón et al. (2013) an age of around 122.8 m.y..
Note: Possible apomorphies are in bold. However, the actual level at which many of these features, particularly the more cryptic ones, should be assigned is unclear. This is partly because many characters show considerable homoplasy, in addition, basic information for all too many is very incomplete, frequently coming from taxa well embedded in the clade of interest and so making the position of any putative apomorphy uncertain. Then there is the not-so-trivial issue of how ancestral states are reconstructed...
Chemistry, Morphology, etc. Drimane-type sequiterpenoids are practically restricted to Canellales; they are quite diverse in Canellaceae but are relatively uncommon in Winteraceae (Bastos et al. 1999).
For nodal anatomy, see Sugiyama (1979), for general vegetative anatomy, see Metcalfe (1987), and for a comparison of general embryology and seed coat anatomy, see Tobe and Sampson (2000).
Phylogeny. For relationships in the order, see e.g. Massoni et al. (2014).
Includes Canellaceae, Winteraceae.
Synonymy: Winterales Reveal - Winterineae Shipunov - Winteranae Doweld - Winteridae Doweld
CANELLACEAE Martius Back to Canellales
Vessel elements with scalariform or reticulate perforations; true tracheids +; sieve tube plastids with peripheral protein fibrils; leaves spiral or two-ranked; inflorescence variable; receptacular cortical vascular system +; flowers red; K 3, C (4-)5-12, free (connate); A 6-12(-many), connate, (connective little produced), wall epidermis persistent; pollen (trichotomosulcate), ektexine microreticulate to psilate granular [Cinnamosma intectate]; G [2-6], also occluded by secretion, compitum +, placentation parietal, style short, stigma lobed; ovules 2-many/carpel, campylotropous, micropyle bistomal, zig-zag, outer integument 4-8 cells across, parietal tissue?, nucellar cap 0; fruit a berry, K persistent; seeds ruminate or not; exotesta sclerosed, rest undistinguished, (?pachychalazal - Cinnamosma); endosperm development?; n = 11, 13, 14.
5[list]/13. Tropics; U.S.A. (S. Florida), Antilles, South America, E. Africa, Madagascar (map: from Jackeline Salazar Lorenzo). [Photo - Flowers]
Evolution. Ecology & Physiology. For vascular flow in Canellaceae, see Hudson et al. (2010) and Feild et al. (2011: Canella winterana is a little odd).
Chemistry, Morphology, etc. Are the sepals "really" bracts - perhaps unlikely? - or bracteoles (for the latter, see Hiepko (1964). There has been discussion on the insertion of the petals, whether spiral or whorled, and if whorled, the number of whorls; Wilson (1966) also noted that the sepals have two traces and the petals three, although inner petals may have only a single trace. A vestigial aril has been reported from some genera (Igersheim & Endress 1997).
Some information is taken from Kubitzki (1993b); for chemistry, see Hegnauer 1964, 1989, 1990 - the last under Winteraceae), also Bastos et al. (1999: drimane-type sequiterpenoids).
Phylogeny. For a phylogeny of Canellaceae, see Salazar and Nixon (2008); Cinnamomodendron is polyphyletic.
WINTERACEAE Lindley Back to Canellales
(Plant Al accumulator); vessels 0; rays 10+-seriate; (petiole bundles complex); leaves spiral, lamina vernation supervolute; inflorescence cymose (fasciculate); "K" 2, connate and forming calyptra, (calyptra splitting early), with 2+ traces, "C" with 1-3 traces, (outer members connate); A spiral, 3-many, (subintrorse), filaments stout, expanding during anthesis, (connective prolonged), both secondary parietal cell layers dividing, endothecium biseriate [fibrous outer layer of middle wall layer]; pollen in tetrads, acalymmate [each grain has separate exine], (monads), monoporate (trichotomocolpate), semitectate-coarsely reticulate; stigma bilobed, (not decurrent); ovules (1-)5-many/carpel, nucellar cap 2-3 cells across; endostome persistent, cells thick-walled, outermost enlarged; K deciduous in fruit; seed with palisade exotesta, (tegmen subfibrous).
5[list]/60-90 - two groups below. Montane tropics, not mainland Africa (map: from Vink 1993; Marquínez et al. 2009 [New World]: for fossil localities outside the range of extant members of the family, see Doyle 2000b - mauve = early Cretaceous, green = late Cretaceous to Tertiary [not in the sea]).
Age. Although some estimates of the divergence of Takhtajania from other Winteraceae are only (53-)46, 41(-34) m.y. (Wikström et al. 2001), Marquínez et al. (2009) suggested that Takhtajania diverged ca 120 m.y.a. , while the comparable age in Bell et al. (2010: note topology) is (27-)18.5(-11) m.y.
Fossils assigned to Winteraceae have a much wider distribution than that of the family today (Doyle 2000b, see map above). Pollen tetrads about 122.5 m.y. old from Gabon have been assigned to Winteraceae, while other slightly younger, common, and more widespread pollen types are less certainly associated with the family (e.g. Doyle et al. 1990a; Doyle 1999). The earlier Cretaceous records are of calymmate tetrads, that is, the ectexine forms a continuous covering over the tetrad, that have fine ornamentation, and grains of this type (e.g. Walkeripollis, see Schrank 2013 and references) have been placed sister to Winteraceae in a constrained morphological analysis (Doyle & Endress 2010). Fossil wood has been reported from the end-Cretaceous Maastrichtian of California (see Vink 1993, for literature).
1. Taktajanioideae Leroy
Lignification in stem diffuse; reaction wood 0; flowers red; "K" with four more members; anther thecae transverse; G , collateral, placentation parietal, placentae subapical, oblique to horizontal, compitum +; outer integument 4-5 cells across, (inner integument 4 cells across), parietal tissue 5-6 cells across; fruit ?"septifragally" dehiscent; n = 18.
1/1: Takhtajania perrieri. Madagascar.
Synonymy: Takhtajaniaceae J.-F. Leroy
2. Winteroideae Arnott
Sesquiterpene dialdehyde cinnamates +; (tracheid walls vestured); sieve tubes with non-dispersive protein bodies; (petiole bundles numwerous, arrangement complex); stomatal apertures often occluded by wax-cutin plugs; flowers ± white; "K" with 0-4 more members, "C" 2-13; (anther thecae transverse); G (1-)5-many, free (connate); outer integument 3-4 cells across, inner integument 2(-3) cells across, parietal tissue 2-5 cells across, hypostase +; fruit berrylet (follicle); cotyledons convolute [Drimys]; n = 13, (19 43).
3-6/60-90. New Guinea to New Zealand and New Caledonia, few Borneo and the Philippines and South America, usu. not lowlands in the tropics. [Photo - Flower.]
Synonymy: Drymidaceae Baillon
Evolution. Divergence & Distribution. Feild et al. (2012: suppl.) estimated divergence began within Tasmannia (T. lanceolata splitting from other Australian and New Guinean species) at 59.1-49.2 m.y.a.. There has been a major radiation of the genus in New Guinea in particular (ca 40+ species), with morphologically and ecologically very distinctive species growing together yet showing at most uncommon hybridisation, and there are more species in in Borneo and Australia at least..
Evolution. Ecology & Physiology. The occlusion of the stomatal apertures that is common in Winteroideae seems to prevent these apertures from being wetted (Feild et al. 1998, 2000a); most Winteraceae grow in moist, cool environments. For vascular flow in Winteraceae in conditions where freezing may occur, see Feild et al. (2002); their tracheids are relatively immune to freezing-induced xylem embolism, particularly compared to the vessel-containing wood of Canella. Drimys (= Tasmannia) cordata is a rather odd vessel-less liana (Feild et al. 2012).
Pollination Biology & Seed Dispersal. The flowers of some Winteraceae show thermogenesis (Seymour 2001), and pollination is by a diversity of small insects, including thrips. In New Caledonia adults of the primitive jawed moths, Sabatinca (Micropterigidae, sister to all other Lepidoptera), eat the pollen of Zygogynum; the tetrads are covered by much oily pollen-kitt which makes them stick to the moths. Sabatinca also uses the flowers as a place of assembly prior to mating (Thien et al. 1985: see also Nothofagaceae). Adults of other jawed moths eat the pollen and spores of a variety of other plants, including asterids and ferns (Imada et al. 2011 and references). Tasmannia is usually dioecious.
Genes & Genomes. The substitution rate of ITS rDNA seems to have been notably slow (Suh et al. 1993).
Chemistry, Morphology, etc. Takhtajan (1997) suggests there are no alkaloids; Cronquist (1981) claims that there are at least some. Sesquiterpene dialdehyde cinnamates are known only from Winteroideae, and prenylated flavanones have recently been found in Pseudowintera (Larsen et al. 2007).
Compression wood has been reported from Drimys (Westing 1965). Keating (2000a) found that the leaf traces may sometimes have paired vascular bundles. The pericyclic sclerenchyma is of various origins (Metcalfe 1987). The petiole vasculature is often quite complex (Keating 2000a and references). For the stomatal morphology of Takhtajania, see Baranova (2004a), but c.f. Keating (2000a: brachyparacytic).
Deroin (2000) noted that there are no cortical bundles in the flower. Doust (2000) described the complexity of phyllotactic patterns in the perianth; he also described the sepals as being lateral in position, and he did not mention bracteoles. Petals of Drimys s.l. and some other taxa have either one or three vascular bundles at the base (see also Canellaceae), as have the sepals, but only a single trace leaves the stele (Endress et al. 2000). The carpels of Tasmannia may be plicate. For the fruit anatomy of Takhtajania, see Deroin (2000).
See also Nast (1944) and Tucker (1959: both floral vasculature, variation in vascularization of the corolla), Bailey and Nast (1945: comparative studies), Bhandari (1963) and Bhandari and Venkataraman (1968), both embryology, Hegnauer (1973, 1990: chemistry), Vink (1985, 1993: general), Svoma (1998b: ovules), papers not otherwise cited in Ann. Missouri Botanical Gard. 87(3). 2000, all focusing on Takhtajania, Doust (2000: floral morphology), Floyd and Friedman (2000: endosperm development), Ehrendorfer and Lambrou (2000: chromosome numbers), and van der Ham and van Heuven (2002) and Sampson (2007), both pollen, for further information.
Phylogeny. For the phylogeny of Winteraceae - Drimys s.l. is paraphyletic and the limits of Zygogynum are to be extended - see Suh et al. (1993), Karol et al. (2000), Doust (2003), Doust and Drinnan (2004) and Marquínez et al. (2009). Morphological analyses by Endress et al. (2000) suggested that Takhtajania, which they thought might be polyploid, was more or less associated with Pseudowintera within Winteraceae.
Classification. Is Drimys piperita the only species in Malesia, with Drimys also in S. America, or should there be two genera - Drimys (flowers perfect: South America), and Tasmannia (plant dioecious: Australia-Malesia)? A generic distinction between the Old and New World taxa is strongly supported (see above).