Flora of Thailand
Euphorbiaceae
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Blume, Bijdr. 17: 1168. 1826/27; Hook., Hooker's Icon. Pl. 9: t. 844. 1852; Hook.f., Fl. Brit. Ind. 5: 344. 1887; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.xv: 312, fig. 26. 1922; Gagnep. in Lecomte, Fl. Indo-Chine 5: 542. 1927; Backer & Bakh.f., Fl. Java 1: 473. 1963; Airy Shaw, Kew Bull. 27: 271. 1972; Radcl.-Sm., Bot. J. Linn. Soc. 94: 54, fig. 7. 1987; G.L.Webster, Ann. Missouri Bot. Gard. 81: 54. 1994; Radcl.-Sm., Gen. Euphorbiacearum: 77. 2001; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 122. 2005; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 89. 2014; Welzen, Blumea 61 (2016) 273.— Microelus Wight & Arn., Edinburgh New Philos. J. 14: 298. 1833, n.v.— Stylodiscus Benn., Pl. Jav. Rar.: 133. 1840.
Tree, dioecious, deciduous (flowering when in young leaf), latex red. Indumentum simple hairs, only very locally present. Stipules falcate, early caducous. Leaves alternate, 3-foliolate (to 5-imparipinnate), usually crowded at end of branchlets, petiole long; leaflets symmetric, basally attached, margin serrate with sharp teeth, without glands, surfaces smooth, glabrous; venation pinnate, nerves seemingly looped and closed near margin, veins indistinctly reticulate. Inflorescences axillary to pseudoterminal racemes (B. racemosa) or panicles (B. javanica), pendulous in fruit; flowers single per bract; bracts early caducous. Flowers actinomorphic; sepals 5, free; petals and disc absent. Staminate flowers: pedicel with subbasal abscission zone; sepals hooded around stamens when young, reflexing, valvate; receptacle torus-like, with stamens attached below pistillode; stamens 5, episepalous, filament short, anthers large, latrorse, thecae two, connective narrow; pistillode 5-lobed, infundibuliform. Pistillate flowers: pedicel with abscission zone in ± middle; sepals imbricate, flat; staminodes absent or early caducous, small, strap-like; ovary 3(4)-locular, globose; ovules 2 per locule; style short, stigmas long, apically entire, upper surface with stigmatic tissue. Fruits drupes, (sub)globose, smooth, mesocarp fleshy, endocarp woody. Seeds obovoid, rather crescent-moon-shaped, smooth, naked.
Two species, one locally in China, the other from India to the Pacific. Ones species in Thailand. Classification: Subfam. Phyllanthoideae, tribe Bischofieae.
Bischofia javanica Blume, Bijdr. 17: 1168. 1826/27; Hook.f., Fl. Brit. Ind. 5: 345. 1887; Gagnep. in Lecomte, Fl. Indo-Chine 5: 542, fig. 66: 15-18; fig. 67: 6-10. 1927; Backer & Bakh.f., Fl. Java 1: 474. 1863; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 124, fig. 26, plate V: 2. 2005; in Welzen & Chayam., Fl. Thailand 8, 2: 610, Fig. 1. 2007; Welzen, Blumea 61 (2016) 273, fig. 1, map 1.— Andrachne trifoliata Roxb., Fl. Ind. ed. 1832: 728.1832.— Microelus roeperianus Wight & Arn., Edinburgh New Philos. J. 14: 298. 1833, n.v.— Stylodiscus trifoliatus (Roxb.) Benn. & R.Br., Pl. Jav. Rar.: 133, t. 29. 1840.— Bischofia roeperiana (Wight & Arn.) Decne. in Jacquem., Voy. Inde 4: 153. 1844.— Bischofia cummingiana Decne. in Jacquem., Voy. Inde 4: 153. 1844.— Andrachne apetala Roxb. ex Wall., Numer. List: 7956A. 1847, nomen nudum.— Bischofia trifoliata (Roxb.) Hook., Hooker's Icon. Pl. 9: t. 844. 1852.
Tree up to 40 m high, dbh up to 2 m; buttresses often present. Outer bark thin, slightly cracked to usually flaking with fibrous, thin strips or scaling, pale reddish to usually dark brown; inner bark pink to light reddish to cream inside, soft; sapwood white to light red, soft to hard; heartwood dark beefy red. Stipules c. 5 by 1.7 mm. Leaves 3-foliolate; petiole 5.5-16.5 cm long, petiolules up to 6.5 cm long, especially central one longe; leaflets mainly elliptic, 5-18 by 2.8-10 cm, length/width ratio 1.4-2.3, base cuneate, occasionally with two glandular teeth at point of petiole insertion on upper surface, apex acuminate, upper surface dark green, lower surface light green; nerves in 7-8 pairs. Inflorescences up to 32 cm long in fruit. Staminate flowers c. 2.5 mm in diameter; red in bud, yellowish when open; pedicel c. 2.6 mm long; sepals almost circular, c. 1.2 by 1.1 mm, light green, apex rounded, slightly hairy; torus c. 0.5 mm high; filaments 0.5-0.6 mm long, light green, anthers c. 1 by 0.8 mm, yellow-green to light yellow. Pistillate flowers quickly developing into fruits; pedicel in fruit up to 11 mm long; sepals ovate, 2.1-4 by 0.8-1 mm, apex acute; staminodes up to c. 0.5 mm high; ovary green; style c. 0.7 mm long, stigmas 4.5-5 mm long, whitish. Fruits 8-10 by 7-10 mm, dark red to brown. Seeds c. 4.2 by 3.2 by 3 mm.
T h a i l a n d.— NORTHERN: Chiang Mai (Ban Bing Kong, Ban Mae Sae, Doi Chiang Dao, Doi Pui, Doi Suthep, Fang, Mae Pa Bo), Chiang Rai (Muang Pua), Lampang (Doi Khun Tan); EASTERN: Nakhon Ratchasima (Khao Laem); SOUTH-WESTERN: Kanchanaburi (Huai Banhau, Koeng Chada); CENTRAL: Saraburi (Phu Khae); SOUTH-EASTERN: Chon Buri (Khao Khiao), Chanthaburi (Khao Soi Dao); PENINSULAR: Krabi (Khao Sato).
D i s t r i b u t i o n.— India (Assam, Kerala), Bangladesh, China (Guangdong, Guizhou, Hainan, Hong Kong), Taiwan, Japan (Ryukyu Islands), Malay Peninsula, Sumatra, Java (type), Borneo, Philippines, Sulawesi, Lesser Sunda Islands, Maluku, New Guinea, Solomon Islands, E. Australia, New Caledonia, Vanuatu, Fiji, Tonga, Cook Islands. Note the absence in Indochina (Laos, Cambodia, Vietnam).
E c o l o g y.— In many different habitats: primary wet evergreen to dry evergreen to deciduous to disturbed forest, beach forest, riparian forest, degraded scrub forest, thickets, village commons; usually in wetter places, often along streams, forest margins, roads; on sand, loam, clay, limestone, coral reef. Altitutude: sea-level up to 1000(-2350) m. Fruits eaten by Oriolus birds.
V e r n a c u l a r.— Toem (เติม) (Northern); du som (ดู่ส้ม) (Kanchanaburi, Nakhon Ratchasima).
U s e s.— Medicinal use in China (Hainan); fruits eaten in Borneo (Sarawak); wood used for firewood in New Guinea and for fencing (grows!) in the Solomon Islands; in the latter the squeezed bark or the latex is used as a brown or black dye.