The families of flowering plants

L. Watson and M.J. Dallwitz

Sargentodoxaceae Stapf

~ Lardizabalaceae.

Habit and leaf form. Lianas. Climbing; stem twiners, or scrambling. Leaves deciduous; alternate; long petiolate; non-sheathing; simple (sometimes), or compound (usually); usually ternate. Lamina when simple dissected (usually), or entire (rarely); when simple-dissected, palmatifid (trilobed); palmately veined, or pinnately veined (?); cross-venulate. Leaves exstipulate. Vegetative buds scaly.

Axial (stem, wood) anatomy. Young stems with solid internodes. Pith parenchymatous, but with a group of sclerosed cells at the centre. Cork cambium present; initially deep-seated (in the inner pericycle). Nodes tri-lacunar. Primary vascular tissues comprising a ring of bundles (four large bundles, and eight smaller ones alternating with them towards the outside). Internal phloem absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring, or anomalous (?). Primary medullary rays wide.

The vessels up to 200 microns. The vessel end-walls simple. The axial xylem with tracheids; with fibre tracheids (these in radial rows, the pits circular with crossed apertures).

Reproductive type, pollination. Plants dioecious. Female flowers with staminodes (six). Gynoecium of male flowers vestigial. Floral nectaries present. Nectar secretion from the perianth (from the petals). Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence units racemose. Inflorescences axillary; drooping racemes, from scaly axillary buds. Flowers bracteate; minutely bi- bracteolate; small; regular; 3 merous; partially acyclic. The gynoecium acyclic. Floral receptacle not markedly hollowed (elongated and becoming swollen and fleshy). Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla (the calyx green, but petaloid in texture); 12; 4 whorled; isomerous; petaloid. Calyx 6; 2 whorled (3+3); polysepalous; regular; imbricate. Corolla 6; 2 whorled (3+3); polypetalous (the petals very small, scalelike, nectariferous); regular; green.

Androecium in both male and female flowers, 6. Androecial members free of the perianth; free of one another; 2 whorled (3+3). Androecium of male flowers, exclusively of fertile stamens. Stamens 6; shortly filantherous. Anthers basifixed, or adnate (? — the thecae separated by a broad connective); non-versatile; dehiscing via longitudinal slits; extrorse; oblong, bilocular; appendaged. The anther appendages apical (the connective prolonged into a short, terminal projection). Pollen grains aperturate; (2–)3 aperturate; colporate (colporoidate).

Gynoecium 25–100 carpelled (‘many’). Carpels increased in number relative to the perianth. Gynoecium apocarpous; eu-apocarpous (the carpels imbricate and spiralled on the elongated torus); superior. Carpel non-stylate (the style subulate); 1 ovuled. Placentation apical to marginal (subapical to ventral). Ovules funicled; pendulous; hemianatropous to anatropous.

Fruit fleshy; an aggregate. The fruiting carpel indehiscent; baccate (the stipitate ‘berries’ becoming black and pruinose when ripe, and the receptacle becoming elongated and fleshy). Fruit 1 seeded. Seeds copiously endospermic. Endosperm fleshy, oily (and starchy). Seeds with starch. Embryo well differentiated (but minute). Cotyledons 2. Embryo straight (excentric).

Physiology, phytochemistry. Aluminium accumulation not found.

Geography, cytology. Holarctic and Paleotropical. Temperate. Central China.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Ranunculiflorae; Ranunculales. Cronquist’s Subclass Magnoliidae; Ranunculales. APG III core angiosperms; peripheral eudicot; Superorder Ranunculanae. APG IV Order Ranunculales (as a synonym of Ladizabalaceae).

Species 1. Genera 1; only genus, Sargentodoxa (S. cuneata).

General remarks. Seemingly differing from Lardizabalaceae only in the more numerous, spiralled and one-ovuled carpels, and the deep-seated cork cambium.

Illustrations. • Sargentodoxa cuneata: Hutchinson. • Sargentodoxa cuneata: Makins (1937). • Sargentodoxa cuneata: Chittenden.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 15th April 2018.’.