Volume 8 > Part 1 > Year 2005 > Page 283 > Euphorbiaceae > Euphorbia

16. Euphorbia ridleyi Croizatwfo-0000964432

Gard. Bull. Singapore 9: 147. 1937.

Accepted Name : This is currently accepted.

Synonyms & Citations :

Description : Erect shrub, up to 60 cm high (to 1.5 m high fide Croizat, loc. cit.), unbranched, with thick, slightly succulent stem (to 8 mm diam.); glabrous. Stipules irregularly triangular, 0.3–0.5 mm long, undivided, Leaves petioles to 10–15 mm long (Croizat: to 35 mm long); alternate, often absent in lower part; blades obovate, 9–13 by 4–6.5 cm (Croizat: to 21 by 7 cm), slightly succulent, base narrowly acute and narrowed into the petiole, margin entire, apex rounded to subacute, slightly brighter below; midrib thick but additional venation very indistinct, not triplinerved, side veins in ca 9 pairs. Cyathia solitary in the axils of upper leaves (sometimes in pairs fide Croizat), only staminate ones seen, green, with a peduncle of 2–4 mm; involucral bracts 2–2.5 mm long, yellow or pinkish; glands 4–5, transversely elliptic, ca 2 mm wide, dark yellow, without appendages. Pistillate flowers not studied, still undescribed. Fruits not studied, but described by Croizat (loc. cit.) as having a distinct pedicel (pedicel and peduncle together 8 mm long), 8 by 13 mm, sulcate, with stigmas completely divided. Seeds not studied, still undescribed.

Thailand : PENINSULAR: Surat Thani (Phanom), Nakhon Si Thammarat (Khao Luang, Khao Rum), Yala (Banang Sata).

Distribution : Malay Peninsula (excluding Singapore, type).

Ecology : Epilithic on stream sides, in evergreen forests along waterfall, or on rocky place near river in shaded primary evergreen forests, 50–400 m alt. Flowering: February, May, July, October, November.

Vernacular : Plao ka (เปล้ากา), rak luk ma (รักลูกหมา)(Peninsular).

Uses: Used as medicine for poulticing burns.

Notes: This species is mostly known as Euphorbia synadenium Ridl., when describing the species, was aware that the older name E. synadenia Baill. existed, but considered both name as distinct enough to be valid both. Croizat (l.c.) disagreed and published a new name (E. ridleyi). He mentioned that Baillon's name of Euphorbia synadenia, describing an African species, has been erroneously cited as ‘synadenium’ in the literature, and therefore the risk of confusion exists. The ICBN is quite vague on the matter of confusingly similar names (Art. 53.3), but I feel that use of Croizat’s name, E. ridleyi, avoids any doubts and is preferred here.