The families of flowering plants
Including Decaisneaceae; excluding Sargentodoxaceae.
Habit and leaf form. Lianas (with striate branches), or shrubs (Decaisnea). Self supporting, or climbing (mostly); when climbing, stem twiners; Akebia, Stauntonia twining anticlockwise. Leaves alternate; petiolate; non-sheathing; compound; pulvinate; ternate, or pinnate (only in Decaisnea), or palmate. Leaflets pulvinate. Lamina pinnately veined, or palmately veined (usually); cross-venulate. Leaves usually exstipulate.
General anatomy. Plants with laticifers (Decaisnea), or without laticifers. The laticifers of Decaisnea only in the fruits.
Leaf anatomy. Abaxial epidermis usually papillose, or not papillose (Holboellia). Stomata present; anomocytic. Adaxial hypodermis present (usually), or absent (Holboellia). The mesophyll containing calcium oxalate crystals. The mesophyll crystals druses (rarely), or solitary-prismatic (usually). Minor leaf veins without phloem transfer cells (Holboellia).
Axial (stem, wood) anatomy. Young stems with solid internodes. Pith homogeneous (the peripheral cells sometimes thicker-walled). Cork cambium present; initially superficial. Nodes tri-lacunar. Primary vascular tissue comprising a ring of bundles; collateral. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays wide.
The wood diffuse porous. The vessel end-walls simple (usually), or scalariform and simple (Decaisnea). The vessels with spiral thickening, or without spiral thickening. The axial xylem without tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres; including septate fibres (rarely), or without septate fibres. The fibres without spiral thickening. The parenchyma very sparse or absent. Included phloem absent. The wood partially storied (VP, VPI).
Reproductive type, pollination. Unisexual flowers present. Plants monoecious, or dioecious, or polygamomonoecious (Decaisnea, Holboellia). Female flowers with staminodes (six, small), or without staminodes. Gynoecium of male flowers pistillodial to absent. Floral nectaries present, or absent. Nectar secretion from the perianth, or from the androecium (from the honey-leaves, when these present).
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in racemes (these often drooping). The ultimate inflorescence units racemose. Inflorescences axillary; solitary or fascicled racemes, often drooping, originating from scaly axillary buds. Flowers bracteolate, or ebracteolate; small; often fragrant; regular; 3 merous; cyclic (commonly P3+3, A3+3, G3 or more). Free hypanthium absent.
Perianth with distinct calyx and corolla, or sepaline; 3, or 6, or 9–12, or 12–50; isomerous. Calyx 3 (Akebia), or 6 (usually, rarely many, commonly petaloid, but small); 1 whorled (Akebia), or 2 whorled (mostly, rarely more?); polysepalous; regular; imbricate, or imbricate and valvate (the outer members sometimes valvate). Corolla when present, 6 (smaller than the sepals, in the form of nectariferous honey-leaves between P and A cf. Ranunculaceae); 2 whorled; polypetalous; regular.
Androecium 6. Androecial members free of the perianth; free of one another (Akebia, Holboellia), or coherent (usually, via connate filaments); when joined, 1 adelphous. Androecium of male flowers exclusively of fertile stamens. Stamens 6; alternisepalous (opposite the petals, when these present); opposite the corolla members (when C present); laminar (the sacs often more or less embedded in a laminar-thickened connective), or filantherous. Anthers adnate (or embedded); dehiscing via longitudinal slits; extrorse (or the thecae tilted upwards in Sinofranchetia); tetrasporangiate; appendaged (usually apiculate, by terminal prolongation of the connective), or unappendaged (muticous in Akebia). Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or decussate. Anther wall initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; (2–)3 aperturate; colpate, or colporate (col(por)oidate); 2-celled.
Gynoecium 3 carpelled, or 6–15 carpelled; apocarpous; eu-apocarpous (the divergent carpels in 15 whorls of three); superior. Carpel fully closed, or incompletely closed (e.g.in Akebia); more or less non-stylate (the stigma sessile or subsessile); apically stigmatic; (4–)10–100 ovuled (usually numerous). Placentation marginal (the ovules biseriate along the ventral suture, in Decaisnea), or dispersed (usually, the ovules inserted all over the carpel wall in separate alveolae). Stigmas wet type; non-papillate. Ovules orthotropous to anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral (Holboellia), or persistent. Synergids pear-shaped. Endosperm formation cellular.
Fruit fleshy; an aggregate. The fruiting carpel dehiscent, or indehiscent; a follicle (fleshy), or baccate. Seeds endospermic. Endosperm oily. Embryo well differentiated (small). Cotyledons 2; flat. Embryo straight.
Seedling. Germination phanerocotylar.
Physiology, phytochemistry. Sugars transported as sugar alcohols + oligosaccharides + sucrose (Holboellia). Not cyanogenic. Alkaloids absent (one species). Arbutin absent. Iridoids not detected. Saponins/sapogenins commonly present. Proanthocyanidins present, or absent; cyanidin (Holboellia). Flavonols present; kaempferol and quercetin. Ellagic acid absent (3 species, 2 genera). Aluminium accumulation not found. Sieve-tube plastids S-type.
Geography, cytology. Holarctic, Paleotropical, and Neotropical. Temperate to sub-tropical. Himalayas to Japan, Chile. 2n = 28, 30, 32.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Ranunculiflorae; Ranunculales. Cronquists Subclass Magnoliidae; Ranunculales. APG 3 core angiosperms; peripheral eudicot; Superorder Ranunculanae; Order Ranunculales.
Species 35. Genera 8; Akebia, Boquila, Decaisnea, Holboellia, Lardizabala, Parvatia, Sinofranchetia, Stauntonia.
Economic uses, etc. The fleshy follicles of Akebia spp. are edible.
Illustrations. • Technical details: Decaisnea, Holboellia, Lardizabala. • Technical details: Akebia (Goebel).
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 19th October 2013. http://delta-intkey.com’.