Flora of Thailand

Euphorbiaceae

 

23. Claoxylon

 

P.C. van Welzen

 

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Genus description

Identification key

Species descriptions

 

Claoxylon

 

A.Juss., Euphorb. Gen. Tent.: 43. 1824; Müll.Arg. in DC., Prodr. 15, 2: 775. 1866; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii: 100. 1914; Airy Shaw, Kew Bull. 26: 233. 1972; Whitmore, Tree Fl. Malaya 2: 27. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 69. 1975; G.L.Webster, Ann. Missouri Bot. Gard. 81: 88. 1994; Radcl.-Sm., Gen. Euphorbiacearum: 217. 2001; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 159. 2005; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 120. 2014 Erithrocilus Reinw. ex Blume, Bijdr.: 614. 1826 Quadrasia Elmer, Leafl. Philip. Bot. 7: 2656. 1915.

 

Subshrubs to small trees, dioecious. Indumentum of simple hairs, villose or sericeous, glabrescent. Stipules small, triangular, caducous. Leaves alternate, simple; petiole often with apical glands adaxially, not pulvinate; blades symmetric, papery, usually rough, margin (laxly) dentate with teeth ending in small glands, apex acuminate to cuspidate, other glands absent, nerves pinnate, veins usually scalariform, veinlets reticulate. Inflorescences solitary, unbranched racemes, staminate ones with groups of flowers per node, pistillate ones with single flowers per node; bracts ovate, small; bracteoles minute; flowers actinomorphic; sepals 3-5, valvate, less hairy to glabrous inside; petals absent. Staminate flowers pedicelled; disc lobes among stamens, strap-like, apically with tuft of hairs; stamens 20-50, filaments thin, anthers 2-locular, locules separate, diverging, basally attached to small connective; pistillode absent. Pistillate flowers pedicelled; sepals ovate; disc lobes flat, 5-lobed, sometimes larger than sepals, sepaloid; ovary 3(4)-locular, 1 ovule per locule; stigmas sessile, not forked, broadly papillate above, resembling Selaginella. Fruits loculicidally dehiscing capsules, somewhat ribbed on sutures, usually densely tomentose; column slender. Seeds globose, completely covered by an arillode.

    Paleotropical genus of c. 75 species, ranging from Madagascar through S. and S.E. Asia, Malesia to Melanesia and Hawaii; four species in Thailand. Classification: subfam. Acalyphoideae, tribe Acalypheae, subtribe Claoxylinae.

 

Key to the species

 

1a.

Lower leaf surface hairy to touch (hairs patent, velutinous);  blade length/ width ratio < 2.

1. C. indicum

1b.

Lower leaf surface glabrous or rough to touch (hairs absent or appressed, sericeous); blade length/width ratio >2.

2

2a.

(At least some) petioles apically with adaxial glands, up to 3.5 cm long. Blades rather smooth, obovate, drying (bluish/purplish) greenish. Staminate inflorescences up to 3.5 cm long (petioles and inflorescences short). Fruits rather glabrous.

3. C. oliganthum

2b.

Petioles usually without glands, seldom with. Blades (rather) rough to touch, elliptic (to some obovate), either drying green and then petioles and staminate racemes up to 12.5 cm or drying purplish and then petioles up to 7 cm long and staminate racemes up to 20 cm long. Fruits densely tomentose (unknown for C. putii).

3

3a.

Leaves drying green. Petioles up to 12.5 cm long. Staminate inflorescences up to 12.5 cm long.

2. C. longifolium

3b.

Leaves drying purplish. Petioles up to 7 cm long. Staminate inflorescences up to 20 cm long (rare plant, only known for Chiang Mai).

4. C. putii

 

1. Claoxylon indicum (Reinw. ex Blume) Hassk., Cat. Hort. Bog.: 235. 1844; Hook.f., Fl. Br. India 5: 410. 1887; Gagnep. in Lecomte, Fl. Gén I.-C. 5: 422. 1926; Airy Shaw, Kew Bull. 26: 233. 1972; Whitmore, Tree Fl. Malaya 2: 78. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 71. 1975; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 160, plate VIII: 2. 2005.— Erytrochilus indicus Reinw. ex Blume, Bijdr.: 615. 1825 Erytrochilus mollis Blume, Bijdr.: 615. 1825 Erytrochilus minor Blume, Bijdr.: 616. 1825 Croton halecum Roxb., Fl. Ind. ed. 2, 3: 683. 1832 Claoxylon parviflorum Hook. & Arn., Bot. Beech. Voy.: 212. 1841 Claoxylon macrophyllum Hassk., Pl. Jav. Rar.: 251. 1848 Claoxylon minus (Blume) Hassk., Pl. Jav. Rar.: 251. 1848 Claoxylon molle (Blume) Miq., Fl. Ned. Ind. 1, 2: 386. 1859 Claoxylon polot auct. non Burm.f.: Merr., Interpr. Rumph.: 220. 1917; Backer & Bakh.f., Fl. Java 1: 480. 1963.

 

       

 

Shrubs or trees up to 8 m tall, flowering branchlets up to 12 mm thick, mainly villose all over, glabrescent. Stipules minute, triangular, c. 0.5 by 0.3 mm. Leaves: petiole up to 8 cm long, usually with 2 glands, hardly adaxially longitudinally grooved; blade ovate (to elliptic), 13-25 by 7-15 cm, length/width ratio 1.7-2, rough to touch, base emarginate to attenuate, above less hairy than underneath, nerves 9-12 per side, ending open near margin. Staminate racemes up to 33 cm long, yellow-green; flowers in groups of up to 8; bracts c. 2 by 1 mm. Staminate flowers c. 4.5 mm in diameter, green to white; pedicel 2-3 mm long; sepals 3 (or 4), ovate, 2.3-2.5 by 1.2-1.3 mm; disc lobes c. 0.4 mm high; stamens c. 20, filaments 1.4-1.5 mm long, anthers 0.4-0.5 mm long. Pistillate racemes up to 7.5 cm long, dull light green; bracts c. 1.4 by 1.4 mm. Pistillate flowers c. 2.7 mm wide, green; pedicel 2-3.8 mm long; sepals 3 or 4(5), 1.3-1.8 by 0.9-2 mm; disc lobes smaller than sepals; ovary 3- or 4-locular, c. 2 by 2.7 mm wide; stigmas c. 1.1 mm long. Fruits 8-9.5 by c. 5 mm, dull light green to bluish green, densely whitish tomentose; column c. 4 mm long. Seeds 3-3.8 mm in diameter, arillode red.

    T h a i l a n d NORTHERN: Mae Hong Son, Nan, Tak, Phitsanulok; NORTH-EASTERN: Khon Kaen; EASTERN: Nakhon Ratchasima; SOUTH-WESTERN: Kanchanaburi, Phetchaburi, Prachuap Khiri Khan; CENTRAL: Saraburi; SOUTH-EASTERN: Prachin Buri, Chon Buri, Chanthaburi; PENINSULAR: Chumphon, Ranong, Surat Thani, Trang, Yala).

    E c o l o g y Evergreen forest, disturbed hill evergreen forest, open areas with secondary growth, roadside clearings; soil: limestone, granitic. Altitude:80-1650.

    V e r n a c u l a r Khang namphueng (้างน้ึ้ง), ngun phueng khao (้น้ึ้ง) (Northern); chap paeng  (บแ้ง) (Uttaradit); phak wan bai yai (านญ่) (Chanthaburi); hu khwai () (Nakhon Si Thammarat); kha ka ai (้า), phak wan chang khlong (าน้างลง) (Peninsular).

 

2. Claoxylon longifolium (Blume) Endl. ex Hassk., Cat. Hort. Bog.: 235. 1844; Hook.f., Fl. Br. India 5: 441.1887; Gagnep. in Lecomte, Fl. Indo-Chine 5: 421. 1926; Back. & Bakh., Fl. Java 1: 481. 1963; Airy Shaw, Kew Bull. 26: 234. 1972; Whitmore, Fl. Malay Penins. 2: 79. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 72. 1975; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 161, fig. 35. 2005.— Erytrochilus longifolius Blume, Bijdr.: 16. 1825 Claoxylon papyraceum Airy Shaw, Kew Bull. 23: 77. 1969 (only type specimen).

 

Claolong-habit.gif (92876 bytes)    Claolong-male.gif (33864 bytes)    Claolong-female.gif (54050 bytes)    Claolong-fruit.gif (51084 bytes)    Claolong-seed.gif (5251 bytes)

 

Undershrub to treelet, up to 5(-15) m tall, flowering branchlets up to 5 mm thick, only sericeous when young. Stipules triangular, 1-3.5 by 0.6-1 mm. Leaves: petiole up to 12.5 cm long, seldom with glands, adaxially longitudinally grooved; blade elliptic (to obovate), 7.5-22 by 2.5-10 cm, length/width ratio 2-3.6, rough to touch, base broadly to narrowly attenuate, decurrent, only midrib below sericeous when older, nerves 8 or 9 per side, only apically looped and closed near margin. Staminate racemes up to 12.5 cm long; flowers in groups of up to 6; bracts c. 0.8 by 0.7 mm. Staminate flowers c. 4 mm in diameter; pedicel c. 4 mm long, yellow-green; sepals 3(-5), ovately elliptic, often unequal, 2.1-2.8 by 1-3 mm, yellow-green to white; disc lobes c. 1.2 mm long; stamens c. 40, filaments c. 2 mm long, light yellowish below, whitish above, anthers c. 0.2 mm long. Pistillate racemes up to 7 cm long. Pistillate flowers c. 3.5 mm wide; pedicel 2.5-3 mm long; sepals 3 or 4, 1-1.2 by 0.8-1.5 mm; disc lobes partly united, 3 larger than sepals; ovary 3-locular, c. 4 by 3.5 mm wide; stigmas 1.5-1.8 mm long. Fruits c. 11 by 8 mm, green to brownish, densely tomentose; column 5-6 mm long. Seeds 4.5-5 mm in diameter.

    T h a i l a n d SOUTH-WESTERN: Kanchanaburi (Kao Ri Yai); PENINSULAR: Surat Thani (Kao Naung), Phangnga (Ao Luk, Kan Bow Koranee Cascade, Khao Phra Mi), Phuket (Kamala, Ton Sai Waterfall), Krabi (Khao Pra, Nai Chong), Nakhon Si Thammarat (Khao Luang, Kiriwong), Trang (Khao Chong), Satun (Koh Tarutao, Nam Tok Baripath); Songkhla (Dton Nga Chang Park), Pattani (Kao Kalakiri), Yala (Tarn To), Narathiwat (Bacho).

    D i s t r i b u t i o n N.E. India to S.E. Asia and W. Malesia up to Borneo and Java (type) and possibly New Guinea.

    E c o l o g y Evergreen forest, gallery forest; soil: granitic rock, sandstone, limestone; Altitude: 50-950 m.

    V e r n a c u l a r Phak wan chang (าน้าง) (Peninsular).

 

3. Claoxylon oliganthum Airy Shaw, Kew Bull. 32: 71. 1977; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 161. 2005.— Claoxylon kingii auct. non. Ridl.: Airy Shaw, Kew Bull. 26: 234. 1972.

 

Shrub to treelet, up to 2 m tall; flowering branches up to 5 mm thick, only sericeous when young. Stipules not seen. Leaves: petiole 0.7-3.5 cm long, usually (at least some leaves) with glands, adaxially somewhat longitudinally grooved; blade obovate, 12.5-25 by 5-10 cm, length/width ratio c. 2.5, rather smooth to the touch, base cuneate, (sub)glabrous when old, sericeous when young, nerves 8-10 per side, looped and closed near margin. Staminate racemes up to 3.5 cm long. Staminate flowers: pedicel c. 2 mm long; sepals 3, ovate; stamens 25-30, anthers cream. Pistillate racemes up to 2 cm long. Pistillate flowers seen in young stage; pedicels 0.5-3.5 mm long; sepals 3, 1.2-1.5 by c. 1.2 mm; disc lobes inconspicuous, much smaller than sepals; ovary 3-locular, c. 1.5 by 1.8 mm; stigmas 1.3-2.5 mm long. Fruits c. 12 by 5 mm, glabrous to subsericeous, green. Seeds c. 5 mm in diameter, arillode orange.

    T h a i l a n d EASTERN: Nakhon Ratchasima (Pak Thong Chai); PENINSULAR: Ranong (Khao Pawta Luang Kaeo), Phangnga (Khao Bangto, Khao Phra Mi).

    D i s t r i b u t i o n Endemic (type: Kao Bangto, Phangnga, KERR 17205, holotype K, isotye BK).

    E c o l o g y Evergreen hill forest; Altitude: 500-1300 m.

    V e r n a c u l a r Phak wan phangnga (านพังงา) (Phangnga).

    N o t e Leaves usually drying a bit purplish.

 

4. Claoxylon putii Airy Shaw, Kew Bull. 25: 519. 1971; Kew Bull. 26: 234. 1972; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 163. 2005— Claoxylon papyraceum auct. non Airy Shaw: Airy Shaw, Kew Bull. 23: 77. 1969 (excl. type).

 

Treelet, only sericeous when young. Stipules not seen. Leaves: petiole up to 7 cm long; blade elliptic, 15-25 by 5-8 cm, length/width ratio c. 3, rough to touch?, drying purplish, base cuneate, only midrib below sericeous when older, nerves c. 8 per side. Staminate racemes up to 20 cm long; flowers in groups of 3-5. Staminate flowers pedicelled; sepals 4, densely sericeous outside; disc lobes purplish; stamens 45-50; filaments purplish. Pistillate racemes and fruits unknown.

    T h a i l a n d NORTHERN: Chiang Mai (Pang Tawn).

    D i s t r i b u t i o n Endemic (type: Pang Tawn, Chiang Mai, PUT 3860, holotype K).

    V e r n a c u l a r Phak wan pang tong (าน) (Chiang Mai).

    N o t e Only known from the type specimen. This could well be a very local form of C. longifolium, the length of the petioles overlaps and only the colour of the (dried) leaves and the length of the staminate inflorescences is different.