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FOC | Family List | FOC Vol. 11 | Euphorbiaceae

57. Trigonostemon Blume, Bijdr. 600. 1826.

三宝木属 san bao mu shu

Authors: Bingtao Li & Michael G. Gilbert

Enchidium Jack; Poilaniella Gagnepain; Prosartema Gagnepain.

Trees or shrubs, monoecious. Leaves simple, alternate, rarely opposite to nearly whorled; stipules small, persistent or deciduous; leaf blade unlobed, pinnately veined, sometimes stipulate at base, paired glands at apex of petiole. Flowers androgynous or anisogynous; inflorescences terminal or axillary, racemose or thyrsoid. Male flowers: sepals 5, free, imbricate; petals 5, exceeding calyx; disk cupular or annular, or shortly divided, or dissected, sometimes divided into 5 glands; stamens 3-5; filaments connate or only free at upper part; anther connective enlarged, often elongated, thecae adnate to thickened connectives; pistillode absent. Female flowers: pedicels usually prominently stronger than axil of inflorescence; sepals and petals as in male; disk annular or cupular, usually unlobed; ovary 3-locular; ovules 1 per locule; styles 3, free, connate at near base, bifid or unlobed at apex. Capsules 3-valved. Seeds not carunculate; testa dry; endosperm present; endosperm fleshy; cotyledon broad and flat.

About 50(-80) species: tropical Asia, extending from India and Sri Lanka to New Guinea; eight species (one endemic) in China.

See P. T. Li et al. (Harvard Pap. Bot. 11: 117-120. 2006) for a review of Trigonostemon in China.

1 Leaves usually in dense pseudowhorls at tips of branches; petiole less than 1 cm; inflorescences unbranched, racemelike   (2)
+ Leaves evenly spaced; petiole 1-11 cm; inflorescences branched   (4)
2 (1) Leaf blade abaxially glabrous; sepals uniform in size; petals yellow; ovary and fruits glabrous.   1 T. xyphophylloides
+ Leaf blade abaxially villous or hirsute; sepals unequal in size; petals purple-red; ovary and fruits densely hirsute   (3)
3 (2) Bracts leaflike, 10-25 mm; inflorescence less than 6 cm.   2 T. flavidus
+ Bracts linear or linear-lanceolate, 3-6 mm; inflorescence 15-25 cm.   3 T. howii
4 (1) Leaf blade glabrous, apex shortly acuminate to acuminate   (5)
+ Leaf blade pilose or pubescent, apex obtuse to caudate   (6)
5 (4) Leaf blade broadly elliptic, margins entire or obscurely serrulate; basal veins 3; petals white or yellowish white; stamens 3.   4 T. albiflorus
+ Leaf blade obovate, margins sparsely serrate; venation pinnate; petals yellow; stamens 5.   5 T. thyrsoideus
6 (4) Pedicels filamentous; petals elliptic.   6 T. bonianus
+ Pedicels more robust; petals obovate   (7)
7 (6) Sepals unequal in size; leaf blade adaxially densely tuberculate.   7 T. chinensis
+ Sepals uniform in size; leaf blade adaxially not tuberculate.   8 T. fragilis

Lower Taxa


Related Objects  
  • LI, P.T. et al. 2006. Notes on Trigonostemon (Euphorbiaceae) for the Flora of China
  • PDF
  • Trigonostemon.pdf
  • PDF

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