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Vines, typically herbaceous; rhizomatous or tuberous. Stems twining clockwise or counter-clockwise, branched or not, smooth or winged, polygonal or terete, glabrous or sometimes bearing prickles; some species producing bulbils (branches modified into small aerial tubers) in leaf axils. Leaves initiated in spiral pattern, modified in some species and appearing opposite or whorled. Inflorescences: staminate nodes at ultimate flowering spicate or paniculate, individual flowers grouped in bracteolate cymes of (1–)3(–8) sessile or pedicellate flowers; pistillate solitary or rarely fasciculate, 1 flower per node, sessile or subsessile, unbranched, subtended by pair of minute bracts. Flowers unisexual, staminate and pistillate flowers on different plants or rarely staminate and pistillate flowers on same plant; tepals glandular or not, 1–3(–30) mm; staminate flowers with filaments distinct (connate basally only in D. polystachya), gynoecium rudimentary; pistillate flowers with staminodes present or sometimes absent, ovary inferior, usually 2–3 times length of perianth, style 3-branched, branches 2-fid; pedicel, when present, not articulate. Fruits capsular, 3-winged, dehiscence loculicidal, perianth and styles generally persistent. Seeds (1–)2 per locule, compressed, usually winged unilaterally, bilaterally, or with wings expanded circumferentially; tannins, saponins present. x = 9, 10.
Tubers 1 or sometimes 2 or more, usually deeply descending into the soil, annually replaced, never poisonous though sometimes unpleasant to eat, chiefly from tannins and saponins. Stem twining to the right, usually armed, particularly at the base. Hairs usually absent, if present as stiletto hairs (Fig. 6) or dendroid hairs. Extra-floral nectaries of the deep kind. Leaves entire, opposed or alternate; on thin axes alternate, on axes thicker at origin opposite; petiole not auriculate at the base. Male flowers in spikes axillary or more generally cauliflorous. Flower fleshy, particularly the torus (Fig. 4e-g), the latter not enlarging into a cup, in some spp. of Celebes growing upwards; tepals incurved through anthesis so that the flower scarcely expands; outer tepals ovate, ¾-2 mm, inner ones narrower at the base and ± shorter and blunter. Filaments as long as the introrse anthers. Bract repressed against the axis and curving round the bud, not so in ♀ flowers; bracteole inserted within one margin of it. Female flowering axes decurved, 1 to 3 together from a leaf axil; flowers and capsules facing forward; wings of the capsules as broad as or broader than long; stipe growing proportionately with the ripening capsule. Seeds winged all round with a smoky brown, membranous wing conform to the loculus, of 2-3 cm diam.
Tubers descending into the soil, apparently not to a considerable depth, protected against herbivores in some spp. and probably in all by a poisonous saponin in addition to thorny roots on the surface of the tubers. Corm little developed for new tubers appear in the axils of scale leaves against the soil, as if misplaced bulbils. Hairs, when present, of the stiletto shape as in D. pyrifolia of § Enantiophyllum (Fig. 6d). Extrafloral nectaries of the deep kind exist, at least in D. piscatorum. Bulbils not recorded. Leaves entire, cordate, alternate, chartaceous. Male flowers one at a time along spreading flowering axes. Torus expanded into an infundibular tube from the rim of which the tepals become reflexed during anthesis. Female flowering axes decurved, carrying numerous pedicellate flowers which face forward; but after fertilization the pedicel lifts the capsule to a horizontal position (Fig. 5d). Style stout. Capsules horizontal when ripe or very slightly ascending, elongated, their sides parallel. Seeds with a triangular body and winged from it on the outer side and forward (in the Tonkin species also from the base).
Tubers renewed annually from a corm that is superficial in the soil, stalked or not, or in D. hispida as lobes on the corm, harmless or poisonous, sometimes very poisonous. Plants as a rule pubescent with characteristic hairs (Fig. 6b-c, e). In the Malaysian species the lower equidimensional cell of the hair is single; elsewhere it may be doubled. Sometimes both cells are coloured red, sometimes only the lower. Extrafloral nectaries superficial. Stems twining to the left, in most species prickly at the base. Leaves alternate palmately compound, usually with 3 or 5 leaflets, sometimes simple. The forerunner tip is not well-developed and in most species receives but a single nerve. Male flowers one at a time along the flowering axes; pedicellate (except in D. hispida), the pedicel growing out of the stem carries up the bract with the flower. The flower-carrying axes are assembled into large leafless inflorescences. Female flowers on downwardly directed axes and after pollination reflexed. Capsules rather longer than twice their breadth. Seeds winged towards the base of the cell.
wining vines; leaves simple, alternate or opposite, petiolate, usually cordate at base, acuminate, entire or lobate, glabrous or pubescent with simple hairs, not tendril-bearing, palmately veined, the secondary veins reticulate; flowers regular, unisexual (dioecious); perianth segments 6, similar, equal, ovate to linear-oblong, connate at base; stamens 6, or 3 (rarely alternating with 3 staminodia), borne on perianth segments or on a central disk, free or connate; anthers small, free, open-ing by longitudinal slits, introrse or extrorse; rudimentary ovary present or absent in the staminate flowers; pistillate flowers with or without minute staminodia; ovary inferior, linear or oblong, 3-celled; ovules 2 in each cell, superposed, pendulous, anatropous; styles 3, short; fruit a loculicidally dehiscent, 3-valved capsule; seed winged at base or all around.
Tuber annually replaced, solitary, produced close under the surface of the soil, swelling downwards from a rather thick attachment; in Asia and the East that attachment does not possess any length, but in Africa it makes a definite stalk; flesh poisonous in varying degree, the least poisonous being cultigens derived from D. bulbifera. Hairs as a rule absent, when present finger-like and of one cell. Extra-floral nectaries of the superficial kind. Leaves cordate, alternate. Male flowers in spikes or spike-like racemes which may be collected together into large inflorescences; torus without enlargement, tepals long and narrow. Female flowers on decurved axes and after pollination the ovary is reflexed. Capsules twice as long as broad or relatively longer. Seeds winged towards the base of the cell.
Tubers 4 to many, thrust downwards from a corm lying close to the surface of the soil, esculent, and protected in the wild plant by a formidable cheval-de-Frise of thorny roots, wherein the longest thorns are those directed upwards; but races of cultivation are largely without thorns. Plant abundantly hairy with T-shaped hairs (Fig. 6a). Extra-floral nectaries are of the deep kind (see family description). Bulbils absent. Leaves alternate, entire and cordate or broadly cordate. Male flowers almost always one at a time distributed along rather stiff axes which ascend from distal leaf-axils; if there be more than one flower the arrangement is cymose. Torus expanded into a saucer-shaped tube. Female flowers on decurved spikelike racemes; capsules reflexed.
Herbs twining. Rootstock rhizomatous or tuberous, variable in color, shape, chemical constituents, and depth in ground. Bulblets axillary or absent. Leaves alternate or opposite, petiolate, simple or palmately compound, basal veins 3--9. Flowers unisexual (plants dioecious, rarely monoecious), arranged spirally in axillary, usually elongate spikes or racemes, or in small cymules in ± spikelike thyrses, these often several together, sometimes gathered into a terminal or axillary panicle by reduction of subtending leaves. Male flowers: stamens 6, 3 sometimes reduced to staminodes or absent. Female spikes 3.5--10 cm, few flowered. Female flowers: staminodes 3, 6, or absent. Capsule 3-winged, dehiscent apically at maturity. Seeds with a membranous wing.
Underground a rhizome, often short; but there are species in which by report it may be 2 m long. Plant glabrous (in Malaysia), stems twining to the left. Bulbils only produced (rarely) in D. prazeri. Leaves alternate, simple but not always entire, invariably with large auricles at the base of the lamina making it cordate in varying degree. ♂ Flowers in cymes disposed racemosely on leafless flowering axes; cymes 2-4-flowered reduced to 1 distally. ♀ Flowers on decurved or pendent leafless axes, almost spicate; after fertilization the pedicel reflexes the capsule so that it faces upwards. Seeds at maturity of the capsule which dehisces from the upper end downwards winged all round, but not evenly.
Underground one or more descending tubers. Plants glabrous, stems twining to the left, apparently unarmed. Bulbils unknown. Leaves, it seems, always alternate, typically cordate, but not invariably (cf. D. stenomeriflora). Male flowers pedicellate, one at a time along leafless branches which are decurved in all the species except D. stenomeriflora; the pedicel carries a bracteole above mid-length and is reflexed in all the species except D. stenomeriflora so that the flower faces upwards. Stamens 6. Female flowers distinctly pedicellate, on decurved spike-like racemes similar to those of the male except that the pedicels do not become reflexed.
Dioecious; infls axillary; fls white to greenish-yellow, the pistillate solitary at each node of the short, interrupted spikes, the staminate in small glomerules or solitary at each node of the panicle; stamens 6; fr a 3-winged loculicidal capsule; seeds very flat, broadly winged. 600, mainly trop. and subtrop.
Stems sometimes bearing axillary bulbils. Fruit a 3-lobed capsule, dehiscing around the lobe margins. Seeds ovate, flat, winged.
