Botanical Survey of India | Flora of India

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42. Trigonostemon Blume, nom. cons.

Shrubs or small trees, with simple hairs, monoecious. Leaves alternate, often falsely whorled and then often separated by bare internodes, penninerved or sometimes triplinerved at base, long or short petioled; stipules short or obsolete. Inflorescences axillary or terminal, occasionally cauli- or ramiflorous, unisexual or bisexual, variously cymose (often abbreviated or even reduced to a solitary flower), thyrsiform, racemiform or pseudoracemose, rarely withconspicuous foliaceous bracts. Male flowers: shortly pedicelled; sepals 5, imbricate, sometimes dorsally gibbous; petals 5, free, exceeding the sepals, mostly brightly coloured; disc glands 5, often connate; stamens 3 (- 4) or 5 or very rarely 13; filaments connate or rarely somewhat free or rarely lacking; anthers 2-loculed, extrorse, vertical to horizontal; connectives broad, often produced and horn-like; pistillode absent. Female flowers: pedicels initially short, gradually elongating; sepals 5, imbricate, rarely fringed with capitate glands; petals 5, free, coloured as in males, caducous; disc glands free or united; ovary 3-locular, glabrous or pubescent; each locule 1-ovuled; styles 3, bifid or occasionally simple or quadrifid, erect or spreading. Fruits tricoccous capsules, often depressed, smooth or verruculose; seeds trigonous, orbicular or ovoid; endosperm fleshy; cotyledons flat, broad.

Sri Lanka, S. & NE. India to China and Malesia, ca 90 species; 5 species in India.

Literature. BALAKRISHNAN, N. P. & T. CHAKRABARTY (1991). A revision of Trigonostemon Bl. (Euphorbiaceae) for Indian subcontinent. Candollea 46: 601 - 637, ff. 1 - 12.


1a. Leaves clearly trinerved at base; inflorescences bisexual 5. Trigonostemon viridissimus
b. Leaves solely penninerved, never trinerved at base; inflorescences unisexual 2
2a. Female inflorescences with a few conspicuous foliaceous bracts 1. Trigonostemon aurantiacus
b. Female inflorescences without such foliaceous bracts 3
3a. Inflorescences reduced, short, up to 3.5 cm long 3. Trigonostemon semperflorens
b. Inflorescences not reduced, much longer 4
4a. Petioles bistipellate at apex with glandular appendages below the lamina on both sides; sepals often conspicuously dorsally gibbous; anthers sessile with thecae separated from one another and partially embedded on somewhat triquetrous fleshy coherent connectives, forming a globose mass as a whole on the receptacle 2. Trigonostemon nemoralis
b. Petioles not bistipellate at apex; sepals not gibbous; anthers not as above, but subtended by a connate column of filaments 4. Trigonostemon villosus

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