Dichapetalum Thouars

Lianas, lianescent shrubs, shrubs, or small trees with sympodial growth. Stems often with intruding phloem; branches solid or hollow, often distinctly lenticellate, the lenticels in vertical rows or scattered. Stipules caducous or persistent, simple, entire, or variously lobed or divided. Leaves spirally arranged on the orthotropic shoots, but pseudo-distichous on the plagiotropic shoots, strongly reduced to absent on orthotropic shoots in lianas, shortly-petioled, pinnatinerved, margins entire; orbicular, usually flat glands nearly always present on the leaf-blade, mostly beneath. Inflorescences axillary, sometimes arranged on leafless axillary or terminal shoots, cymose, distinctly branched or subglobose, sessile or pedunculate; peduncle free or adnate to the petiole; bracts and bracteoles usually small; pedicel articulate, the upper part (the true pedicel) variable in length, absent to very distinct Flowers small, actinomorphic, 5-merous, bisexual in African species. Receptacle flat or slightly concave. Sepals unequal to subequal, imbricate, free or shortly united, rarely forming a tube. Petals whitish to pale yellow, equal, alternating with the sepals, ± spathulate in outline, at base usually as wide as the filaments and adnate to them, rarely the petals entirely free, bilobed to entire, the lobes flat or concave. Stamens 5, equal, episepalous; anthers introrse, opening by longitudinal slits, usually with a strongly thickened connective. Staminodes 5, epipetalous, variously shaped, sometimes united into a disk-like lobulate ring or cupula. Pistil 2–3(–4)-merous; obturator often present; styles free or coherent. Fruit with 1–3(–4) pyrenes, subglobose or deeply lobed, usually yellow to orange at maturity; exocarp dehiscent or indehiscent; mesocarp fleshy; endocarp indehiscent, with a distinct apical, and usually partly ventral, suture, leathery or bony, often hairy inside. Seeds exalbuminous, usually with a rather thin testa; cotyledons planoconvex, often grooved on the convex sides.

The Malaysian species are mostly confined to the substage of the rain-forest, ascending to c. 1800 m altitude. Only one species (D. timoriense) is growing in part of its area under semi-arid (seasonal) climatic conditions in SE. Java and the Lesser Sunda Islands.None of the species plays a predominant role in the forest vegetation and as a matter of fact the genus is on the whole inconspicuous and scarce. No data worthy of note are available on pollination or dispersal.In most species the 'lobes' of the drupes show a marked marginal lengthwise 'suture' suggesting a line of dehiscence; however, no dehiscence has been observed.

Uses. No useful plants of any repute are among Malaysian Dichapetalum. In Africa some species are very poisonous by a most remarkable toxic compound (acetic fluor, ch2 F COOH), unique in the plant kingdom. See R. PETERS ( R. PETERS Endeavour 13 1954 147 ).