Botanical Survey of India | Flora of India

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Claoxylon A.Juss.

Trees or shrubs, rarely herbs, dioecious or monoecious, evergreen. Leaves alternate, lower ones rarely opposite, often pellucid-dotted above in living plants with protruding points which become scabrous when dry, penninerved, rarely palmately 3-nerved at base, usually long-petioled; stipules small or minute. Flowers small, in axillary or lateral spikes or racemes, solitary or 2 together. Male flowers: 1 - many fascicled in each bract; calyx subglobose, closed in bud, splitting into 3 or 4 valvate segments; petals and disc absent; stamens 3 - 60 or more, free, inserted on or around a central flat, vaulted, convex or elevated receptacle, often intermixed with intrastaminal glands or long linear scales or hairs; filaments free, short; anthers erect; thecae distinct, connate at base, free above, extrorsely dehiscing; pistillode absent. Female flowers: solitary in each bract; sepals 3 (- 5), shortly connate at base; disc absent or consisting of petal-like hypogynous scales, glandular, enlarged, 2 - 3-lobed with elongate liguliform lobes alternating with the carpels; staminodes absent; ovary (2 -) 3 (- 4)-loculed; ovule solitary in each locule; styles same number as ovary-locules, coarsely papillose inside, often plumose; stigmas short, divided into fringed segments or rarely smooth. Fruits schizocarpic capsules, 2 or 3 (- 4)- locular, deeply or shallowly lobed, fleshy or coriaceous, dehiscing loculicidally and septicidally or indehiscent; seeds subglobose, with a fleshy outer and hard foveolate-reticulate crustaceous inner layer (testa), thinly arillate or not arillate; endosperm fleshy; cotyledons broad, flat.

Paleotropical, spread over Africa, Asia, Australia, extending eastwards to Pacific Islands, up to Society Islands, ca 113 species; 9 species in India.

Literature. PRAIN, D. (1911). A review of the genera Erythrococca and Micrococca. Ann. Bot. (Usteri) 25: 575 – 638. SAGUN, V. G. & P. VAN WELZEN (2002). Revision of the Malesian species of Micrococca (Euphorbiaceae). Blumea 47: 149 – 155. SUSILA RANI, S. R. M. & N. P. BALAKRISHNAN (1992). Claoxylon wightii Hook. f. (Euphorbiaceae) and its allies. J. Econ. Taxon. Bot. 16: 733 – 736. SUSILA RANI, S. R. M. & N. P. BALAKRISHNAN (1995). A revision of the genus Claoxylon Adr. Jussieu (Euphorbiaceae) in India. Rheedea 5: 113 - 141, ff. 1 - 8.

Notes. Following Prain (1911), Sagun & van Welzen (2002) treat Micrococca and Claoxylon as independent genera. However, they have not seen the paper by Susila Rani & Balakrishnan (l. c. 1995), nor have they studied Indian species of Claoxylon. Micrococca Benth. is based on certain differentiating characters, i. e. the herbaceous nature, the opposite lower leaves, interrupted racemes, lesser number (3 - 20) of stamens, plumose styles, loculicidally and septicidally dehiscing capsules with thinly arillate seeds. However, analysis of all Indian species of Claoxylon indicated that these characters are variable and often becomes intermediate. There are two species endemic to India, C. beddomei and C. wightii, which show a bridge between Micrococca and Claoxylon. The herbaceous nature of M. mercurialis continues into Claoxylon where the species are subshrubs, shrubs or trees. The lower leaves are sometimes opposite in C. anomalum and they are subopposite in C. wightii. The interrupted racemes occur in both genera but only in varying degrees. The stamen number varies from 3 to 10 in Micrococca and from 20 to 60 or more in Claoxylon. M. mercurialis itself shows regional variation with 3 stamens in Asia and 9 stamens in Africa. C. beddomei and C. wightii show 5 - 20 stamens. The disc lobes are present in female flowers of both genera; only the length versus breadth varies showing different lengths in Indian species, sometimes becoming minute and indistinct. In C. anomalum, the female disc is annular with three lobes and each lobe triangular and appressed to the ovary. In C. indicum, C. beddomei and C. wightii, the female disc consists of 3 oblong-ligulate lobes each 1 – 2 mm long. The capsules of C. indicum dehisce both loculicidally and septicidally. In other species, there are no records to show whether both types of dehiscence occur or not, a feature that only careful field observation will show. At the same time, there are certain dependable and invariable characters common to both these genera, i. e. the constantly 3-sepaled male flowers, the divaricate anther-thecae which are connate at base and free above, the stamens mixed with ciliate scales or glands, the presence of pits over seeds, etc., which indicate commonality and propinquity of these genera. Therefore, keeping them separately is not justified by facts. It is also not practical to differentiate them by any decisive character. Therefore, they are combined and treated here as a single genus, as was done by Mueller Argoviensis (1866) and J. D. Hooker (1887).


1 a. Stamens (3 -) 5 - 12 (- 20) 2
b. Stamens 20 - 60 or more 4
2 a. Male receptacle without interstaminal glands, with extra-staminal glands outside the stamens 2. Claoxylon beddomei
b. Male receptacles with interstaminal glands, without extra-staminal glands 3
3 a. Annual herbs or sometimes perennial subshrubs; racemes bisexual, equal to or longer than leaves 7. Claoxylon mercurialis
b. Perennial shrubs; racemes unisexual, shorter than leaves 9. Claoxylon wightii
4 a. Male receptacle elevated, eglandular and glabrous in between the stamens, with a ring of pilose hairs below the stamens 1. Claoxylon anomalum
b. Male receptacle convex or flat, not elevated, glandular and often with scales or hairs intermingled with stamens, without a ring of pilose hairs below the stamens 5
5 a. Capsules flattened, inflated at middle, 2-locular, 2-lobed, cuneate at base, conspicuously beaked at apex 8. Claoxylon rostratum
b. Capsules globose, 3-locular, 3-lobed, not cuneate at base, nor beaked at apex 6
6 a. Interstaminal glands on receptacle mixed with minute hyaline scales, not mixed with tufts of hairs 4. Claoxylon khasianum
b. Interstaminal glands on receptacle mixed with hyaline scales and also a tuft of long hairs 7
7 a. Petioles glandular at apex; male racemes 20 - 40 cm long; stamens 20 - 40, rarely more 3. Claoxylon indicum
b. Petioles eglandular at apex; male racemes 8 - 18 cm long; stamens 35 - 60 8
8 a. Capsules shallowly 3-lobed, thinly puberulous, smooth 5. Claoxylon longifolium
b. Capsules deeply 3-lobed, covered with hirsute prickles 6. Claoxylon longipetiolatum

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