Elateriospermum tapos Blume, Bijdr. 621 (1826)

Synonyms
Elateriospermum rhizophorum Boerl. & Koord.

Diagnostics
Tree with white to yellowish, sticky latex. Vegetative parts glabrous. Stipules present. Petioles clearly swollen at base and top. Leaves alternate in whorls, young leaves bright red, upper leaf with two basal glands. Branched inflorescences with white-yellowis male flowers, female flowers greenish. Fruits a large capsule, splitting open when ripe.

Description
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, glabrous, 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. [from Flora Malesiana]

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. 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).

Distribution
Peninsular Thailand and Malaysia, Sumatra, Java and Borneo.

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