Flora of Thailand
Euphorbiaceae
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P.C. van Welzen, T. Djarwaningsih & W. Nanakorn
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Hassk., Verslagen Meded. Afd. Natuurk. Kon. Akad. Wetensch. 4 140. 1855; Hook.f., Fl. Br. India 5: 468. 1888; Pax in Engl., Pflanzenr. IV.147.v: 54. 1912; J.J.Sm., Bull. Jard. Bot. Buitenzorg II, 6: 100., 1924; Airy Shaw, Kew Bull. 25: 551. 1971; Whitmore, Tree Fl. Malaya 2: 124. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 186. 1975; Kew Bull. 35: 666. 1980; Kew Bull. 36: 339. 1981; Kew Bull. 37: 34. 1982; G.L.Webster, Ann. Missouri Bot. Gard. 81: 118. 1994; Radcl.-Sm., Gen. Euphorbiacearum: 350. 2001; Djarwaningsih, Blumea 49: 412. 2004; Welzen, Djarwaningish & Nanakorn in Welzen & Chayam., Fl. Thailand 8, 2: 507. 2007; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 191. 2014.— Stomatocalyx Müll.Arg. in DC., Prodr. 15, 2: 1142. 1866.— Carumbium Reinw. sect. Pimelodendron (Hassk.) Müll.Arg. in DC., Prodr. 15, 2: 1143. 1866.
(Shrubs to) trees, dioecious. Latex abundant, white, later yellow. Indumentum simple hairs, mainly absent. Stipules absent. Leaves alternate, simple, in terminal groups because of sympodial growth; petiole terete, slender, basally and apically pulvinate; blade elliptic to obovate, symmetric, coriaceous, margin serrulate to serrate, teeth not glandular, apex acute to cuspidate; venation penninerved. Inflorescences axillary (to sometimes ramiflorous when staminate), single (mainly pistillate) or when staminate groups of racemes (to panicles; not in Thailand), flowers single per bract; bracts triangular, often with two additional bracteoles. Flowers symmetric, pedicellate; petals and disc absent. Staminate flowers: buds flattened; calyx 2-lobed, lobes broadly reniform, imbricate; stamens 7-29, in 2 (Thailand) or 3 whorls, filaments free, short, anthers dorsifixed, latro-extrorse, 2-thecate; pistillode absent. Pistillate flowers: calyx 2- or 3-lobed; ovary 3-21-locular, ovules 1 per loculer; style absent to very short, stigmas entire, free or connate, flat to recurved. Fruits drupaceous, orbicular or pyriform, yellow/reddish, glabrous, thick-walled, soft and fleshy when fresh. Seeds globose to reniform, half-enclosed by a broad, shallow multilobulate aril.
A genus of 4, possibly 5 species, ranging from S.E. Asia main land troughout Malesia to the Solomon Islands and N.E. Australia (Queensland); a single species in Thailand. Classification: Subfamily: Euphorbioideae, tribe Stomatocalyceae, subtribe Stomatocalycinae.
Pimelodendron griffithianum (Müll.Arg.) Benth. in Benth. & Hook.f., Gen. Pl. 3: 331. 1880; Hook.f., Fl. Brit. Ind. 5: 468. 1888; Pax in Engl., Pflanzenr. IV.147.v: 56. 1912; Whitmore, Tree Fl. Malaya 2: 125. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 186. 1975; Kew bull. 32: 80. 1977; Djarwaningsih, Blumea 29: 415, fig. 1e, 2b, 3d, map 1. 2004; Welzen, Djarwaningish & Nanakorn in Welzen & Chayam., Fl. Thailand 8, 2: 507, FIg. 65, Plate XXVII: 3. 2007.— Stomatocalyx griffithianus Müll.Arg. in DC., Prodr. 15, 2: 1142. 1866.— Pimelodendron borneense Warb., Bot. Jahrb. Syst. 18: 199. 1894.— Pimelodendron acuminatum Merr., Philipp. J. Sci., Bot. 11: 74. 1916.— Pimelodendron papaveroides J.J.Sm., Bull. Jard. Bot. Buitenzorg III, 6: 104. 1924.
Trees up to 25 m tall. Outer bark light brown to reddish brown, smooth to rugose, thin, soft; inner bark light brown with pale yellow sap, c. 2 mm thick; sapwood pale yellow, soft. Leaves: petiole 1-9.5 cm long; blade elliptic (to obovate), 6.5-18 by 2.5-9 cm, length/width ratio 2-2.6, base attenunate, usually with a pair of glands abaxially, margin serrulate, apices of teeth apiculate, distance between teeth 1-2.1 cm, upper suface dull when dry; nerves 6-8 pairs. Flowers yellowish green, calyx greenish brown. Staminate inflorescences racemose, in groups of up to 4 per axil, up to 8 cm long; bracts c. 1 by 1 mm, bracteoles present, c. 0.25 by 0.25 mm. Staminate flowers 3.8-8.5 by 3-5.8 mm; pedicel 1.5-7.5 mm long; calyx lobes 2-5.5 by 1.5-3 mm, margin entire; stamens 6-10 in 2 whorls, filaments 0.25-1 mm long, anthers 0.25-1 by 0.25-1 mm. Pistillate inflorescences single or 2 per axil, up to 6 cm long; bracts without bracteoles, c. 1 by 1 mm. Pistillate flowers 7.5-12 by 3.8-6 mm; pedicel 3.2-6 mm long; calyx lobes 2-4 by 1.5-3 mm, with scattered glands where united; ovary c. 3 by 2 mm, 4-10-locular; stigmas free, straight. Fruits orbicular, 1.2-3 cm in diameter, glabrous; pedicel up to 3.5 cm long. Seeds reniform, 0.8-1.9 by 0.6- 1.2 cm.
T h a i l a n d.— PENINSULAR: Narathiwat (Sungai Kolok, Waeng).
D i s t r i b u t i o n.— Thailand, Malay Peninsula, Sumatra, and Borneo.
E c o l o g y.— Lowland evergreen forest, secondary forest, pole forest, semi-swamps, along logging roads or on hill slopes; soils dry to wet, sand or clay. Altitude: sea level to 900 m.