ThMicrodesmis

Flora of Thailand

Euphorbiaceae

62. Microdesmis

R. Pooma

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Microdesmis

Planch., Hook. Icon. Pl. 8. t. 758. 1848; Müll.Arg. in DC., Prodr. 15, 2: 1041. 1866; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.iii: 105. 1911; Gagnep. in Lecomte, Fl. Indo-Chine 5: 458. 1926; Airy Shaw, Kew Bull. 26: 362. 1972; Whitmore, Tree Fl. Malaya 2: 118. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 222. 1975; G.L.Webster, Ann. Missouri Bot. Gard. 81: 68. 1994; Radcl.-Sm., Gen. Euphorbiacearum: 126. 2001; Pooma in Welzen & Chayam., Fl. Thailand 8, 2: 450. 2007; Welzen in Noot., Fl. Males. ser. 1, 20: 38. 2011; Kubitzki in Kubitzki, Fam. Gen. Vasc. Pl. 11: 271, Fig. 61a. 2014.

Shrubs or trees, dioecious. Indumentum simple hairs. Stipules small, persistent. Leaves distichous, simple; petiole short; blade eglandular, base unequal, margin entire or serrate, apex mucronulate, surface finely pellucid-punctate, venation penninerved. Inflorescences axillary or supra-axillary fascicles, sometimes on a short peduncle, staminate ones many-flowers, pistillate ones with fewer flowers to solitary; bracts minute. Flowers shortly pedicellate; calyx 5-lobed, lobes imbricate; petals 5, larger than calyx, imbricate or contorted; disc absent. Staminate flowers: stamens 10, in two rows, outer alternipetalous, inner shorter, epipetalous (Thailand), filaments free, anthers basifixed, longitudinally dehiscent; pistillode columnar (Thailand). Pistillate flowers slightly larger and stouter than male ones; ovary 2- (or 3)-locular (Thailand); one ovule per locule; stigmas short, bifid. Fruits drupaceous, subglobose, wrinkled and verrucose when dry, pericarp fleshy, endocarp bony. Seeds subovoid, without caruncle, shiny; endosperm fleshy.

About 10 species, 8 in Africa, 2 in Asia, of which one species in Thailand. Classification: Subfam. Acalyphoideae; tribe Galearieae.

Microdesmis caseariifolia Planch., Hook. Icon. Pl. t. 758. 1848, in adnot.; Hook.f., Fl. Brit. Ind. 5: 380. 1887; Airy Shaw, Kew Bull. 26: 362. 1972; Whitmore, Tree Fl. Malaya 2: 119. 1973; Pooma in Welzen & Chayam., Fl. Thailand 8, 2: 450, Fig. 45. 2007; Welzen in Noot., Fl. Males. ser. 1, 20: 39, fig. 8a–g; map 5. 2011.— Microdesmis philippinensis Elmer, Leaflets Philipp. Bot. 4: 10. 1911.

Shrubs or small trees up to 10 m tall; twigs puberulous when young. Leaves: petiole 3-10 mm long, pubescent; blade elliptic, oblong or slightly ovate-oblong, 4-15 by 1.5-5 cm, length/width ratio 1.7-3, base cuneate, slightly asymmetric, margins serrate, at least the upper half, apex long acuminate to caudate, up to 1.5 cm long, almost glabrous on both surfaces except for the puberulous midrib beneath; nerves 4-7(-10) pairs, strongly curved, arching and looping near margin, venation disting on both sides, veins scalariform-reticulate, midrib slightly sunken to raised above, prominent beneath. Inflorescences with up to 25 flowers when staminate and few-flowered when pistillate. Flowers white to yellowish. Staminate flowers: pedicel 1-5 mm long; sepals ovate, c. 1 mm long, pubescent, petals 0.6-1 mm long, apically round, pilose outside, yellowish; stamens 10, outer 5 longer, filaments c. 0.5 mm long, sparsely hairy, anthers c. 0.3 mm long; connective shortly, acutely elongated. Pistillate flowers: pedicel shorter and stouter than in staminate flowers; sepals ovate, c. 1 mm long, pubescent; petals elliptic, 1.5-2 m long, pubescent; ovary ovoid, ca. 1 by 0.7 mm, glabrous. Fruits 4-7 by 5-8 mm, greenish to white turning orangish yellow. Seeds 2 (or 3).

T h a i l a n d.— NORTHERN: Nakhon Sawan, Uthai Thani; NORTH-EASTERN: Udon Thani, Nong Khai; EASTERN: Nakhon Ratchasima (Khao Yai); SOUTH-EASTERN: Chachoengsao, Chon Buri (Sri Racha), Rayong, Chanthaburi, Trat; CENTRAL: Saraburi; SOUTH-WESTERN: Prachuap Khirikhan; PENINSULAR: Chumphon, Surat Thani, Phangnga, Phuket, Krabi, Nakhon Si Thammarat, Trang, Pattani, Yala, Narathiwat.

D i s t r i b u t i o n.— From S. China, Myanmar and Indochina to Malay Peninsula (type), Sumatra, Borneo and Philippines.

dots = Microdesmis caseariifolia Planch. (stars = M. magallanensis (Elmer) Steenis)

E c o l o g y.— Common in evergreen forest, especially along streams, up to 400 m. Flowering and fruiting throughout the year.

V e r n a c u l a r.— Chan chamot (จันชะมด) (Chanthaburi); salot pa (สลอดป่า) (Trat); mueai (เมือย) (Trang); tana tua mia (ตานาตัว), lamduan dong (ลำดวนดง) (Phuket).