Eusideroxylon zwageri Teijsm. & Binn., Natuurk. Tijdschr. Ned. Ind. 25 (1863)
Named after J. Zwager [1824-?], a Dutch governor in Borneo.
Eusideroxylon borneense Fern.-Vill.
Salgada lauriflora Blanco
Mid-canopy tree up to 40(-50) m tall and 150(-220) cm dbh. Stipules absent. Leaves
alternate, simple, penni-veined, glabrous to slightly hairy below. Flowers ca.
2.6 mm diameter, white-yellow, placed in panicles. Fruits ca. 84 mm long,
grey-green, stony drupes.
An evergreen tree of up to 40(-50) m tall; bole straight, branchless for up to 20 m but usually
less, sometimes slightly fluted at the base, up to 150(-220) cm in diameter; buttresses many,
small, rounded, giving the base an elephant-foot like appearance, in moist places the base often
characteristically set with a mattress of slender rootlets; bark surface red or grey-brown with
thin cracks, debarking in small scab-like subquadrangular pieces which are turned up at the lower
side; exudate absent; crown dense, globular; twigs smooth, slightly angular, tomentellous. Leaves
arranged spirally, simple, entire, leathery, elliptical to ovate, 14-18 cm x 5-11 cm, base
rounded-subcordate, the apex obtuse to shortly acuminate, upper surface glabrous, lower surface
hairy on the larger veins; petiole 6-15 mm; stipules absent. Inflorescence axillary, paniculate,
dense, drooping, 10-20 cm long, densely short-hairy. Flowers bisexual, actinomorphic, on a 3-11 mm
long pedicel; perianth tube shallow, tepals 6, in 2 whorls, imbricate, caducous, 3-3.5 mm long,
greenish, yellow or purplish, puberulous outside; stamens without glands, in 4 whorls, in the
outer 2 whorls staminodial and petaloid, 1.5 mm long, yellowish with a purple tip, ciliate, those
of the third whorl fertile, thick, with minute red or white anthers with a pink hue, anther cells
4, in 1 horizontal row, the central 2 extrorse, the lateral 2 sublatrorse, stamens of the inner
whorl staminodial, subulate, small; ovary superior, sessile, unilocular, with a single ovule,
tapering into the subulate style; stigma small, discoid. Fruit drupaceous, on a thick pedicel,
1 or 2 in each panicle, completely included in and adnate to the accrescent perianth tube,
ellipsoid to ovoid or globular, 7-16 cm x 5-9 cm, glossy black at maturity, containing a single
seed. Seed very large, seed-coat very hard, furrowed, brittle, pale bony; embryo very small.
Seedling with hypogeal germination; cotyledons often partly fused, succulent but tough and long
persistent; internodes sparsely adpressed pubescent; leaves all arranged spirally, conduplicate
or induplicate when young, provided with a lateral branch in each axil. [from PROSEA]
Ulin is a constituent of primary or old secondary tropical rain forest. It thrives in a climate
with an average annual rainfall of 2500-4000 mm. It prefers well-drained soils in valleys or on
hillsides or even low ridges when soil moisture is sufficient. It is found from sea-level up to
500(-625) m altitude. Ulin generally occurs on sandy soils of Tertiary origin, on clay-loam soils
or on sandy silt-loam soils, but large specimens have also been found on limestone. Ulin occurs
scattered or gregarious and is often the dominant canopy species. It sometimes forms almost pure
stands. In Sumatra the 'ironwood forest' is recognized as a distinct forest type characterized
by an exceptionally low species diversity. Ulin occurs also in mixed dipterocarp forest and has
been found associated with Koompassia, Shorea, and Intsia species. Capable of regeneration
via sprouts when cut. Tendency to dominate forest stands. Seed dispersal is apparently often
by water; rich pockets of ulin forest are often found at places where the fruits wash ashore
in large quantities along rivers. Procupines may also disperse the seeds.
Ulin is one of the heaviest and most durable timbers of South-East Asia. As such, it is
preferably used in marine constructions such as pilings, wharfs, docks, sluices, dams and ships
(keels, ribs and decking), or in heavy constructions such as bridges, power line poles, masts,
piles and house posts. Ulin is also used for the traditional houses ('longhouses') of the Dayak
in Borneo. Another major use of ulin is for roof shingles ('sirap') which are reported to last
50 years to more than a century. Less important is the use of ulin as frame, board, for heavy
duty flooring, floodgates, road pavement and foundations, railway sleepers, fencing, printing
blocks, vehicle bodies, sleds for log skidding, furniture, chopsticks, blowpipes, poles (in
pepper cultivation) and survey pegs. The wood is not suitable for plywood or particle board
production. The large fruits are poisonous and pulverized fruits have been used medicinally
Eastern and southern Sumatra, Bangka, Belitung, Borneo and the Sulu archipelago and Palawan
Borneo: Belian, Belian timun, Betian, Talion bening, Tebelian geriting, Telianoii,
Teluyan, Ulin, Ulin bening, Ulion.
English: ironwood, billian.
French: Bilian, bois de fer.
Indonesia: belian (general), onglen (Sumatra), tulian, tebelian (Kalimantan).
Malaysia: belian (Sarawak, Sabah), tambulian (Sabah), im muk (Cantonese, Sabah).
Philippines: tambulian, sakian, biliran (Sulu).