Flora of Thailand



69. Paracroton


H.-J. Esser


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Genus description

Species description




Miq., Fl. Ind. Bat. 1, 2: 382. 1859; Müll.Arg. in DC., Prodr. 15, 2: 1112. 1866; Benth. in Benth. & Hook.f., Gen. Pl. 3: 299. 1880; Pax in Engl. & Prantl, Nat. Pflanzenfam. 3, 5: 85. 1890; in Engl., Pflanzenr. IV.147.iii: 12. 1911; Pax & K.Hoffm. in Engl. & Harms, Nat. Pflanzenfam. ed. 2, 19c: 155. 1931; N.P.Balakr. & Chakrab., Kew Bull. 48: 715. 1994; Radcl.-Sm., Gen. Euphorbiacearum: 318. 2001; Esser in Welzen & Chayam., Fl. Thailand 8, 2: 466. 2007; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 188. 2014.— Fahrenheitia Rchb.f. & Zoll. ex Müll.Arg., Linnaea 28: 599. 1856, nom. inval.; Müll.Arg. in DC., Prodr. 15, 2: 1256. 1866; Benth. in Benth. & Hook.f., Gen. Pl. 3: 299. 1880 (under Ostodes); Pax in Engl. & Prantl, Pflanzenr. IV.147.iii: 17. 1911; Airy Shaw, Kew Bull. 20: 409. 1967, Kew Bull. 26: 270. 1972; G.L.Webster, Ann. Miss. Bot. Gard. 81: 111. 1994; Radcl.-Sm., Gen. Euph.: 318. 2001.— Desmostemon Thwaites, Enum. Pl. Zeyl. 4: 278. 1861.


Trees, monoecious or dioecious, exuding a red sap. Indumentum distinct, consisting of stellate hairs. Stipules small, triangular. Leaves alternate, simple; petiole distinct, variable in length, eglandular; blade simple, symmetric, large, margin entire to serrate, pubescent to various degrees, often with a pair of basal glands above, eglandular below; venation pinnate, lowermost pair often slightly different but not really triplinerved, tertiary veinlets distinct, percurrent. Inflorescences terminal and subterminal, raceme-like with a long axis but flowers often in small groups on short side branches, elongate and drooping, pubescent; staminate and pistillate flowers in separate inflorescences, the staminate ones more distinctly compound; bracts triangular-ovate, glandular or eglandular; staminate flowers several per bract, pistillate ones 1 or few per bract. Flowers actinomorphic, pedicellate, pubescent outside; sepals 5, united at base; petals 5. Staminate flowers: petals free, glabrous; disc dissected; stamens c. 10-30, not inflexed in bud, the outer ones free, the inner ones with united filaments, filaments longer than the anthers, anthers 2-locular, basi-dorsifixed; pistillode absent. Pistillate flowers: petals large, deciduous; staminodes absent; ovary with 3 carpels, smooth, pubescent, with 1 ovule per locule; stigmas 3, apically bifid. Fruits 3-locular, large, nearly globose, smooth, distinctly pubescent, dry, regularly dehiscent. Seeds broadly ellipsoid, brownish, smooth, dry, ecarunculate.

    Three or four species in Asia from Sri Lanka to Burma, Malaysia and the Philippines, a species of doubtful affinity in New Guinea; 1 species in Thailand. Classification: Subfamily Crotonoideae, tribe Crotoneae.

    Note.— Long known as Fahrenheitia, the latter name is now considered to be invalid. The reason is that the authors published it with doubt (‘it seems to represent a new taxon’), and according to ICBN Art. 34 Fahrenheitia was thus not validly published.


Paracroton pendulus (Hassk.) Miq., Fl. Ind. Bat. 1, 2: 382. 1859; Müll.Arg. in DC., Prodr. 15, 2: 1113. 1866; Pax in Engl., Pflanzenr. IV.147.iii: 12. 1911; N.P.Balakr. & Chakrab., Kew Bull. 48: 723. 1994; Esser in Welzen & Chayam., Fl. Thailand 8, 2: 468, Fig. 52; Plate XXIV: 1. 2007.— Croton pendulus Hassk., Pl. Jav. Rar.: 266. 1848.— Fahrenheitia collina Rchb.f. & Zoll., Linnaea 28: 600. 1856; Müll.Arg. in DC., Prodr. 15, 2: 1256. 1866.— Tritaxis macrophylla Müll.Arg., Flora 47: 482. 1864.— Trigonostemon macrophyllus (Müll.Arg.) Müll.Arg., Linnaea 34: 213. 1865; in DC., Prodr. 15, 2: 1106. 1866.— Ostodes macrophylla (Müll.Arg.) Benth. ex Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.iii: 18. 1911; Ridl., Fl. Malay Pen. 3: 269, fig. 153. 1924.— Ostodes pendula (Hassk.) A.Meeuse, Bekn. Fl. Java 4c, fam. 112: 109. 1943; Blumea 5: 508. 1945; Backer & Bakh.f., Fl. Java 1: 493. 1963.— Fahrenheitia pendula (Hassk.) Airy Shaw, Kew Bull. 20: 410. 1967; Kew Bull. 26: 270. 1972; Whitmore, Tree Fl. Mal. 2: 97. 1973.




Trees up to 20 m tall, dbh 25 cm; bark smooth, grey-brown; apical branches distinctly pubescent. Indumentum creamish-brown, consisting of stellate-dendritic hairs, c. 0.2 mm in diam. with c. 8-15 radii. Stipules present as a pair of nearly spherical glands, c. 1 mm in diameter. Leaves: petiole 3-16 cm long, pubescent; blade obovate-elliptic, 16-46 by 7-17 cm, length/width ratio 2.3-2.7, chartaceous, base obtuse to slightly acute, margin serrate with teeth 5-15 mm apart, apex acuminate, both sides distinctly pubescent on midrib and side veins, sparsely pubescent otherwise, basal glands above spherical, c. 1 mm in diameter, sometimes absent, brighter below although not whitish, complete venation distinct, side veins 17-19, arching directly into the marginal teeth (craspedodromous), lowermost pair different and mostly on the basal leaf margin. Inflorescences 20-40 cm long panicles, side branches 1-2 cm long, distant at base and more crowded apically, distinctly pubescent throughout, with yellowish flowers; bracts of side branches c. 3 mm long, linear, often absent, but a pair of nearly spherical glands 1 mm in diameter usually present; side branches with few triangular, eglandular bracts, c. 2 mm long, each subtending several flowers. Staminate flowers densely pubescent outside; pedicels 2-3 mm long; sepals 3-4 by c. 2.5 mm, often with small dorsal appendices; petals c. 5 by 2.5 mm; disk lobed, pubescent with simple hairs. Pistillate flowers: sepals 3-5 by 2.5-3.5 mm, at least in fruit usually with knob-like dorsal appendices; petals c. 4 by 2 mm, glabrous. Fruits: pedicels 10-15 mm long; spherical, 20-21 by 21-22 mm, densely pubescent, brownish, hardly sulcate or carinate. Seeds c. 15 by 12 mm, broadly ellipsoid, flattened, brown with brighter and darker patches.

    T h a i l a n d.— PENINSULAR: Surat Thani (Khao Tha Phet, Ko Samui), Nakhon Si Thammarat (Laanmoomjui Fall, Thung Song), Phatthalung (Tamot Falls), Satun (Ko Tarutao), Songkhla (Boripat Falls), Narathiwat (Bala-Hala, Waeng).

    D i s t r i b u t i o n.— W. Malesia (Malay Peninsula, Singapore, Java (type), Borneo, Philippines), Thailand, not yet recorded for Burma; Desmostemon zeylanicus Thwaites, reduced to a subspecies of P. pendulus by Balakrishnan & Chakrabarthy (loc. cit.), occurs in Sri Lanka and India.

    E c o l o g y.— In shaded primary evergreen and mixed deciduous forest, on granite bedrock. Altitude: 25-200 m. Flowering Mar.-June, Oct., Dec., fruiting May, June, Aug.

    V e r n a c u l a r.— Cha san (จาสั้น) (Peninsular).

    U s e s.— Useful timber tree. On Sabah (Borneo) used medicinally. The red sap is irritating and painful.