Malesian Euphorbiaceae Descriptions

42. ELATERIOSPERMUM (Euphorbiaceae)

Hoang Van Sam & P.C. van Welzen. 2004. Revision of Annesijoa, Elateriospermum and the introduced species of Hevea in Malesia (Euphorbiaceae). Blumea 49: 425–440.

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Genus description

Species descriptions

Excluded species

Elateriospermum Blume

    Elateriospermum Blume, Bijdr. (1825) 620; Müll.Arg. in A.DC., Prodr. 15, 2 (1866) 1130; Benth., Hooker’s Icon. Pl. 13 (1879) pl. 1294; Hook.f., Fl. B. Ind. 5 (1887) 381; Boerl., Handl. Fl. Ned. Ind. 3, 1 (1900) 226; J.J.Sm., Meded. Dept. Landb. Ned.-Indië 10 (1910) 571; Pax in Engl., Pflanzenr. IV.147.i (1910) 17; Ridl., Fl. Malay Penins. 3 (1924) 252; Corner, Wayside Trees Mal. 1 (1940) 249; Backer & Bakh.f., Fl. Java 1 (1964) 496; Airy Shaw, Kew Bull. 16 (1963) 371; Meijer, Bot. News Bull. Forest Dept., Sabah 7 (1967) 25; Airy Shaw, Kew Bull. 26 (1972) 258; Whitmore, Tree Fl. Malaya 2 (1973) 91, f. 6; Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 108; Kew Bull. 36 (1981) 292; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 102; Radcl.-Sm., Gen. Euphorbiacearum (2001) 286; Hoang Van Sam & Welzen, Blumea 49 (2004) 429; in Chayam. & Welzen, Fl. Thailand 8, 1 (2005) 254; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014) 161, Fig. 37. — Lectotype (designated by Webster, 1994): Elateriospermum tapos Blume.

Tree, monoecious. Latex white (to yellowish), sticky, usually abundant, in non-articulated laticifers. Indumentum mainly absent, simple hairs in young parts and inflorescences. Stipules small, early caducous. Leaves simple, alternate, crowded at end of the twigs; petiole relatively long, basally slightly pulvinate, apically pulvinate with 2 disc-like glands adaxially; blade coriaceous, bright red when young, margin entire; venation penninerved, veins and veinlets reticulate. Inflorescences bisexual, axillary to terminal, long-peduncled, cymose panicles, with dichasial terminal branches, central flower of each cyme usually pistillate, rarely staminate. Flowers: pistillate ones larger than staminate ones; sepals in 2 whorls, strongly imbricate, free; petals absent; disc present, densely pilose, with stamens or staminodes inserted in excavations. Staminate flowers: sepals 4 or 5, puberulous; disc thick, fleshy, lobulate, with long white hairs; stamens 10–20(–22), free, filaments short, anthers narrowly obovate, 2-celled, basifixed, opening introrsely with a longitudinal slit, connective apiculate with a gland, thecae parallel; pistillode minute, hairy, or absent. Pistillate flowers: sepals 4–6(–7); staminodes numerous, minute, subulate, ovary ovoid, 2–4-locular, villose; ovules single per locule; style very short; stigmas bend horizontally, apical part split, both parts vertical, one descending, broad and scale-like, the other ascending, triangular. Fruit a large capsule, splitting septicidally and usually partly loculicidally, leaving bivalved cocci; wall rather thick, exocarp somewhat fleshy, endocarp woody. Seeds large, usually 3 per fruit, obovoid with a thin crustaceous chestnut brown testa, ridged ventrally and dorsally, ecarunculate; endosperm scarce; embryo large, white.

    Distribution — Monotypic, as the species.

Elateriospermum tapos Blume

    Elateriospermum tapos Blume, Bijdr. (1825) 621; Müll.Arg. in A.DC., Prodr. 15, 2 (1866) 1131; Benth., Hooker’s Icon. Pl. 13 (1879) pl. 1294; Hook.f., Fl. B. Ind. 5 (1887) 382; Boerl., Handl. Fl. Ned. Ind. 3, 1 (1900) 227; J.J.Sm., Meded. Dept. Landb. Ned.-Indië 10 (1910) 572; Pax in Engl., Pflanzenr. IV.147.i (1910) 17; Merr., J. Straits Branch Roy. Asiat. Soc., Special number (1921) 344; Ridl., Fl. Malay Penins. 3 (1924) 252; K.Heyne, Nutt. Pl. Ned.-Ind., ed. 2, 2 (1927) 942; Burkill, Dict. Econ. Prod. Malay Penins. 1 (1935) 905; Corner, Wayside Trees Mal. 1 (1940) 249; Backer & Bakh.f., Fl. Java 1 (1964) 497; Airy Shaw, Kew Bull. 16 (1963) 371; Meijer, Bot. News Bull. Forest Dept., Sabah 2 (1964) 17; Bot. News Bull. Forest Dept., Sabah 7 (1967) 25; Medway, Biol. J. Linn. Soc. 4 (1972) 131; Airy Shaw, Kew Bull. 26 (1972) 258; Whitmore, Tree Fl. Malaya 2 (1973) 91, f. 6; Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 108; Kew Bull. 36 (1981) 293; Smitinand, Thai Pl. Names, revised ed. (2001) 215; Hoang Van Sam & Welzen, Blumea 49 (2004) 430, fig. 2, map 2; in Chayam. & Welzen, Fl. Thailand 8, 1 (2005) 254. — Lectotype (designated by Hoang Van Sam & Welzen, 2004): Blume 2127 (L), Indonesia, Java, Bantam.

Tree, up to 27(–50) m high, dbh up to 56 cm, bole up to 10 m high, sometimes shortly fluted or with buttresses up to 2 m high, 1.2 m wide and 15 cm thick; crown deeply conical, hemispherical, multilayered, monopodial. Outer bark dirty white to (grey-)brown, c. 1 mm thick, hard, smooth to finely fissured and slightly scaly with c. 1.5 cm long flakes; inner bark red to pale brownish to partly pale yellowish, c. 10 mm thick, fibrous, firm; sapwood white to light yellow; heartwood dark brown. Stipules triangular, 2–3 mm long. Leaves: petiole 1–8 cm long, flat or somewhat hollow adaxially; blade elliptic to obovate, 5–24 by 2–7.5 cm, length/width ratio 2.5–3.2, base obtuse to cuneate, apex abruptly acuminate to cuspidate, upper and lower surface smooth, dark green above, paler beneath; venation raised especially below, nerves 7–17 per side, looped and closed near the margin. Inflorescences up to 19 cm long, hairy, cymules 0.5–6 cm long, bracts triangular, 1–1.4 by 0.7–1 mm, peduncle 2–9 cm long. Flowers white to pale yellow, fragrant with unpleasant scent; buds white. Staminate flowers 2.4–3.5 mm diam.; pedicel 2–7 mm long, hairy; sepals ovate, 2.5–6 by 2.2–5 mm, apex rounded, puberulous outside, glabrescent; disc 0.8–1.3 mm high; stamens yellow, filaments 0.3–2 mm long, orange at base, anthers 0.8–1.2 by 0.2–0.4 mm. Pistillate flowers 3.2–5.3 mm diam.; pedicel 1.3–4.2(–50 in fruit) mm long, hairy; sepals ovate, 4.5–8 by 3.2–5.5 mm; disc 1–1.3 mm high; ovary ovoid, 2.5–4 by 2–2.6 mm, densely hairy, light green; style and stigma thick, 0.3–0.5 mm long. Fruits oblong-ellipsoid, longitudinally 3-grooved, 3.2–5.3 by 2.2–4.5 cm, glabrous, exocarp changing from green via red to turning dark brown (to black), endocarp yellowish. Seeds 3.2–3.6 by 1.4–2.2 cm, brown-grey to dark brown, smooth.

    Distribution — S Peninsular Thailand, Malay Peninsula, Sumatra, Java, Borneo.

    Habitat & Ecology — In hilly primary (mixed dipterocarp) and secondary forest, kerangas forest, forest edges, along logging roads; soil usually deep and yellow-coloured, mainly clay, clay-loam, sandy clay, loam, sometimes sandstone or (silty) laterite. Altitude: sea level up to 600 m. Flowering and fruiting throughout the year. The flowers are visited by dammar bees.

    Uses — A tree of ornamental value. Its flowering indicates the start of the rice season. The seeds are mainly used, but they are usually poisonous (cyanide) when fresh (though a few races are without cyanide). The seeds can be eaten cooked or roasted, but too much may cause dizziness. On Sumatra a paste is made of the seeds (pounded with some water) and used to flavour some kinds of sambal; jungle tribes (Sakai) in Malaysia bury the paste packed in a bag or in bamboo in wet earth for a month or more, the result is a fermented paste with a strong flavour, which is highly appreciated with meals. The fermented paste is also used as fish bait. The oil is seldom pressed from the seeds, pale yellow, nearly odourless and with a nice taste, to be used for cooking or as lamp oil. The wood is usually considered as excellent. The sapwood is white, the heartwood with beautiful dark brown flames. However, it is mainly used as firewood or for small items like handles of rubber tapping knives, because it takes a nice polish. It could have been a good construction timber, but only the sapwood is durable, the heartwood rots easily or is attacked by termites unless treated with preservatives. The seeds make nice toys for children, they are used as toy beetles or threaded together in a game called ‘conquerors’. The latex is used on Sumatra to shield dirty wounds, because it dries quickly; the Bidayuh in Sarawak apply fresh latex once per day to crack wounds on the soles of their bare feet. The latex is also used to polish blowpipes to a glossy dark sheen (Malay Peninsula). Partly after Heyne (1927) and Burkill (1935).

    Vernacular names — Thailand: Kra, pra (Thai); pi-ra (Bidayuh-Malay) (Smitinand, 2001). Malay Peninsula: (Buah) perah, perah kokong (Burkill, 1935; Whitmore, 1973); gua pra, ple prah (Sakai); piah, suing (Semang). Sumatra: Asiloem (Karo); daun tepoes, kajoe si marsang-sang, kedoei, tapoes. Java: Tap(p)os (Sundanese) (Blume, 1825). Borneo: Bramban; kelampai (Iban-Sarawak); layang layang; paha; perah, perah ikan (Malay); rampeh, rapi (Bidayuh).

Excluded species

    Elateriospermum tokbrai Blume, Bijdr. (1825) 621. (= Mallotus tokbrai (Blume) Müll.Arg.) = Blumeodendron tokbrai (Blume) Kurz.