High climbing dioecious shrubs or lianas, sometimes with a robust stem, younger parts of the latter usually hairy and prickly, youngest parts slender and striate, sometimes rolled-in, and simulating tendrils, which are wanting. Leaves remotely spirally arranged, entire or palmately 3-7-lobed, subpalmately 3-7-nerved; petiole from a thickened and depressedly cup-like part of the stem, ± torted, never swollen basally or distally. ♂ Flowers in globose clusters, these either solitary at the end of an axillary peduncle, or several spaced and racemosely arranged then, or generally very numerous in long repeatedly branching spike-like racemes or panicles both axillary and/or stem-borne. Calyx segments 3-5, ± free. Petals 3-4, ± united below, valvate, alternating with the calyx lobes. Stamens 3-4 (rarely-6), finally exserted; filaments filiform, ± connate at base into a column which bears the hirsute rudiment of the ovary; anther cells ovate-elliptic, small. ♀ Flowers in large solitary either cauline or mostly axillary peduncled globose heads. Calyx segments 3-5, free to almost the base. Petals 3-4(-5) as in the ♂ flowers. Staminodes absent. Ovary subovoid-columnar, tapering to an equally thick and short columnar style with several 2-lobed stigmas which form a kind of funnel. Drupes numerous, collected in generally large, globose heads, each drupe tipped by the style, ± reversely setulose by brittle irritant hairs; exocarp thin, larger than the endocarp and ± hollow in the upper extended part at full maturity; endocarp rather thick, ligneous, pitted to deeply lacunose outside, smooth or warty inside. Seed 1, large, with a thin almost juicy coat which exudes a kind of clear gum; endosperm fleshy, strongly furrowed or lobulated; cotyledons very large, flat, foliaceous, double-folded or tortuous.
Scattered in primary and secondary lowland forest, occasionally up to 1200 m, also in open places, as rarely found on limestone rocks.
Uses. The wood has very large porous vessels which contain water, used by the natives, hence the generic name; for its anatomy see the comprehensive study made by TIMMERMANS Ann. Jard. Bot. Btzg 41 1931 65-104 t. 23-34 , and the review given by SLEUMER E. & P. Nat. Pfl. Fam. ed. 2 20b 1942 332-336 f. 90-93 .
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