Flora of Thailand Euphorbiaceae

 

18. Chaetocarpus

 

P.C. van Welzen

 

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Genus description

Species description

Thwaites, Hooker's J. Bot. Kew Gard. Misc. 6: 300. 1854; Baill., Étude Euphorb.: 323. 1858; Müll.Arg. in DC., Prod. 15.2: 1121. 1866; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.iv: 7. 1912; Airy Shaw, Kew Bull. 26: 231. 1972; Whitmore, Tree Fl. Malaya 2: 76. 1973; G.L.Webster, Ann. Missouri Bot. Gard. 81: 65. 1994; Welzen, Rheedea 4: 94. 1994; Thai For. Bull. 28: 56, Fig. 3. 2000; Radcl.-Sm., Gen. Euphorbiacearum: 116. 2001; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 152. 2005; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 103, fig. 21. 2014.— Regnaldia Baill., Adansonia 1 (1860) 187.

Trees or shrubs, dioecious. Indumentum of simple hairs, glabrescent. Stipules very asymmetric, obovate, early caducous. Leaves simple, distichous, blade (a)symmetric, coriaceous, punctate; base broadly attenuate; margin entire; apex acuminate; both surfaces without glands, (sub)glabrous; venation pinnate, looped and closed at the margin, indistinctly reticulate. Inflorescences dense axillary clusters of flowers. Flowers actinomorphic; sepals 4, imbricate, outer 2 different from inner 2; petals absent (to a single, clawed one); disc annular, toothed, teeth in pistillate flowers more numerous and narrower. Staminate flowers: stamens 8 (Thailand), united in an androphore from which the filaments branch alternately. Pistillate flowers: pistil 3- (or 4)-locular; ovules one per locule. Fruits rhegmas, subglobose, densely echinate with glochidiate hairs outside, glabrous inside. Seeds ovoid, covered in upper third by a thin aril.

    Pantropical, 10 or 11 species, one in Thailand. Classification: Subfam. Acalyphoideae, tribe Chaetocarpeae.

Chaetocarpus castanocarpus (Roxb.) Thwaites, En. Pl. Zeyl.: 275. 1861; Müll.Arg. in DC., Prod. 15, 2: 1122. 1866; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.iv: 8. 1912; Gagnep. in Lecomte, Fl. Indo-Chine 5: 471, fig. 59: 12-16. 1826; Airy Shaw, Kew Bull. 26: 231. 1972; Whitmore, Tree Fl. Malaya 2: 76. 1973; Welzen, Rheedea 4: 98. 1994; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 153, fig. 33, plate VIII: 1.1, 1.2. 2005.— Adelia castanicarpa Roxb., Fl. Ind. 3848. 1832.— Gaedawakka castanocarpa (Roxb.) Kuntze, Rev. Gen. 2: 606. 1891, nom. superfl.

(Shrubs to) trees up to 45 m high. Stipules 3—6.5 by 0.6—2.2 mm. Leaves: petiole 3—17 mm long; blade ovate (to elliptic), 3.5—18.5 by 1.5—8 cm, length/width ratio 1.8—3.5, nerves 7—9 per side. Inflorescences densely hirsute. Flowers greenish yellow to white-yellow to yellow, slightly fragrant, sweet; pedicels 3.3—5 mm long, woolly; sepals ovate to rounded, 1.5—3 by 1.5—3.3 mm; disc pink to red. Staminate flowers 2.2—3.7 mm in diameter; stamens: androphore 2.8—5 mm long, hairy, white; filaments 0.4—1 mm long; anthers 0.5—1.2 by 0.4—0.6 mm, yellow. Pistillate flowers up to 7.5 mm in diameter; ovary ovoid, 1—1.3 mm high; styles 3, 0.3—1.2 mm long; stigma lobes 1—2 mm long. Fruit 8—18 by 80—18 mm, yellow turning reddish brown, glochidiate hairs c. 3 mm long. Seeds 5.2—5.5 by 3.5—5 by 2.7—3.5 mm; aril red. Embryo ovoid, flattened, c. 4.3 by 3 mm.

    T h a i l a n d.— NORTHERN: Chiang Mai, Lampang; NORTH-EASTERN: Udon Thani; EASTERN: Chaiyaphum, Nakhon Ratchasima; CENTRAL: Saraburi; SOUTH-EASTERN: Prachin Buri, Chon Buri, Rayong, Chanthaburi, Trat; SOUTH-WESTERN: Kanchanaburi, Prachuap Khiri Khan; PENINSULAR: Chumphon, Ranong, Surat Thani, Phangnga, Krabi, Phuket, Nakhon Si Thammarat, Trang, Songkhla, Satun, Narathiwat.

    D i s t r i b u t i o n.— Sri Lanka, India (type), Assam, Andaman Islands, Myanmar, Cambodia, Vietnam, Thailand, Malay Peninsula, Sumatra, and Borneo.

    E c o l o g y.— Often common, but scattered in (hilly) primary and secondary lowland forest, mixed Dipterocarp forest, coastal peat-swamp forest (kerangas), seasonally swampy forest, Schima-bamboo forest, along beaches and river banks, and in submontane scrubs; soil: yellow, brown or black sandy soil, sandy loam, sandstone, yellow clay, clay-loam, rocky coral, or granite. Altitude: sea level up to 500 m.

    V e r n a c u l a r.— Mak khwai (หมักควาย) (Nakhon Phanom); khi non (ขี้หนอน) (Central); samphao (สำเภา) (Central, Chon Buri); chi (ชี่), si (ซี่) (Prachin Buri); sanan (สนัน) (Trat); a kang (อะกาง), ba-tu (บาตู) (Malay-Narathiwat); dang khao (ดังข้าว) (Phangnga); dang khao mao (ดังข้าวเม่า) (Trang), ma uek khang (มะอึกค่าง) (Surat Thani); padang khao (ปะดังขาว) (Satun); khi non khao (ขี้หนอนขาว) (Peninsular).

    Uses.— In N.E. Malaysia (Kelantan and Trengganu) the young leaves are cooked and eaten as spinach or chopped up with rice. The wood is used as a non-construction timber by the Iban, Sarawak, Borneo; for building purposes in Sri Lanka, and for sampans and columns in Indochina. The wood is said to be light red, moderately hard, close-grained, pores small, scanty, in short radial lines, medullary rays very fine, very numerous, narrow wavy concentric bands fairly regular and prominent.