Eusideroxylon zwageri LAURACEAE The belian seeds in the photo above were drift seeds, found on the sandy beaches of Pulau Maratua an island directly opposite the Berau River mouth at Tanjung Redeb in East Kalimantan.
EUSIDEROXYLON. [Greek, implies that this is the true ironwood] A genus of two species found in Borneo, eastern Sumatra, Bangka, S Philippines (E. zwageri in Tawi Tawi). Local names include belian, or sometimes tulian or tambulian. The preferred timber name is ulin.
Two species occur in Borneo;
Eusideroxylon zwageri is found all over Borneo. The leaves are very fragile and break up into separate little pieces when rubbed, the wood can be split for shingles, the twigs are round. In the flower, only the third whorl of stamens are fertile.
The second species is E. melagangai sometimes in literature in its own genus Potoxylon with nine fertile stamens It is known in Borneo as melagangai or belian-simpoh It is found to the east and north of Sibu town in Sarawak; the leaves are fibrous, the veins hold the pieces together when rubbed, the twigs are square. The wood is difficult to make into shingles The fruit is said to be larger than the other species.
Together, the two species contribute the most valuable timber of Borneo, and as might be expected they have been exhaustively exploited.
The text above is adapted from the excellent Trees of Tropical Asia by James LaFrankie (2010).