Volume 8 > Part 1 > Year 2005 > Page 81 > Euphorbiaceae

7. Aporosa Blume

Bijdr.: 514. 1825; Hook.f., Fl. Brit. Ind. 5: 345. 1887; Pax & K.Hoffm. in Engl., Pflanzenr. IV. 147. xv: 80. 1922; Gagnep. in Lecomte, Fl. Indo-Chine 5: 552. 1927; Airy Shaw, Kew Bull. 20: 380. 1966; Kew Bull. 26: 213. 1972; Whitmore, Tree Fl. Malaya 2: 58. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 30. 1975; G.L.Webster, Ann. Missouri Bot. Gard. 81: 51. 1994; Radcl.-Sm., Gen. Euphorb.: 65. 2001.

Accepted Name : This is currently accepted.

Synonyms & Citations :

Description : (Shrubs to) medium-sized trees, dioecious; latex absent. Indumentum simple hairs. Stipules persistent or caducous. Leaves alternate, simple; petiole reniform, pulvinate at both ends; blade symmetric, usually drying into typical colours, basally often two glands, margin entire to serrate or crenate, usually glands in margin and usually either within nerve arches or outside arches underneath; venation pinnate, nerves looped and closed near margin. Inflorescences simple, thyrsoid spikes, axillary (to ramiflorous), single to many together; staminate glomerules and pistillate flowers spirally arranged; bracts 1 per glomerule or pistillate flower, eglandular. Flowers unisexual (Thailand), small, pedicelled or not; sepals 3–6, imbricate; petals absent; disc absent. Staminate flowers grouped in glomerules; stamens 2–4, episepalous, not to strongly exserted; anthers with 2 thecae; pistillode absent or present. Pistillate flowers solitary; bracteoles small; 2- or 3(4)-locular; ovules 2 per locule; style absent; stigmas apically lobed to completely divided. Fruits dehiscent rhegmas, sometimes beaked and/or stiped, or with ridges along sutures. Seeds covered with a thin, fleshy, juicy, aril.

Eighty-two species and 8 possible species occur from Sri Lanka and S India (Kerala), and from N India east to S China and Indochina, throughout Malesia to the W Solomons; 20 species in Thailand.

Classification: subfam. Phyllanthoideae, tribe Antidesmae, subtribe Scepinae.

Notes: Airy Shaw (1972) often recognised different species than Schot (ms.). Problematic in Aporosa is the A. octandra complex (this roughly coincides with Airy Shaw’s A. dioica). Aporosa octandra is very variable in the northern half of Thailand and extremely difficult to distinguish from A. villosa. Aporosa wallichii, and A. yunnanensis. Several new records are noted for Thailand: A. duthieana (difficult to separate from A. microstachya), A. globifera, A. nervosa, A. penangensis, and A. serrata. Airy Shaw’s A. pseudoficifolia (Myanmar and Malay Peninsula) and A. incisa (a Prunus species) are omitted from this treatment.

The species concept in Aporosa is often difficult, especially in the A. octandra complex (A. octandra, A. villosa, A. wallichii, and A. yunnanensis), where many intermediates exist. The key will only identify the more common forms and ignore the very exceptional forms of which the identification will always remain dubious at most. The colour of the dry leaf is important, due to the accumulation of different metals in the leaves, the colour of dried leaves is often very typical per species (irregardless of the drying method).

E-version notes : The genus is now placed in the family Phyllanthaceae.