Causonis Raf., Raf., Med. Fl.

Trias-Blasi, Anna, Dee, R., Jimbo, Tiberius, Jackes, Betsy & Parmar, Gaurav, 2022, Taxonomic revision of Causonis (Vitaceae) in New Guinea, Edinburgh Journal of Botany 79 (1895), pp. 1-10 : 2-3

Causonis Raf., Raf., Med. Fl. 2: 122 (1830). – Type species: Causonis japonica (Thunb.) Raf.

Cayratia Juss. in Cuvier, Dict. Sci. Nat., ed. 2, 10: 103 (1818), nom. cons. pro parte. – Type species: Cayratia pedata (Lam.) Juss. ex Gagnep.

Columella Lour., Fl. Cochinch. 1: 85 (1790), pro parte. not Columella Vahl nor Columella Vell. – Type species: Columella pedata Lour.

Climbers, herbaceous; hermaphrodite; sometimes tuberous roots present; branchlets terete, with distinct longitudinal ridges; tendrils opposite to leaves, (1–)2–3(–8)-furcate, each branch subtended by a bract. Leaves alternate, pedately (4–)5(–7)-foliolate or trifoliolate; stipules 2, caducous; leaflets usually serrate at margin. Inflorescence a large compound dichasium, leaf-opposed or pseudoaxillary, rarely axillary. Flowers 4-merous; calyx cupuliform; corolla apex cucullate, valvate in aestivation; stamens inserted on the receptacle at the base of the floral disc, opposite to petals, filaments erect, anthers introrse; floral disc cupular and surrounding the ovary, 4-lobed; style conical, stigma minute and undivided.

Fruit a berry, usually globose to oblate, purplish black when mature, 1- to 4-seeded. Seeds triangular, triangular-obovoid or obovoid-elliptic in dorsiventral view, smooth or somewhat angular, convex on the back; beak usually more or less cylindrical; chalaza linear and protruding on surface extending c.1/2 to 2/3 of seed length from apex; raphal ridge distinct; without a distinct membrane covering the ventral infolds, ventral infolds inconspicuous or keel-shaped, cup-shaped or suborbicular in ventral view, horseshoe-shaped or concave in cross-section; endosperm ruminate, T- or m-shaped in cross-section. 2n = 30, 40, 60, 80, 120.