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*''Isoptera sumatrana'' v. Slooten ex Thorenaar (1926), *''Isoptera borneensis'' King non R. Scheffer ex Burck.

*A medium-sized to large tree with bole up to 115 cm in diameter and prominent buttresses; leaves .*Leaves elliptical-oblong, about 16.5 cm × 7.5 cm, with 10 pairs of secondary veins sharply prominent beneath; petals .*Petals narrow, stamens 25; fruit .*Fruit calyx lobes unequal, developed into woody parts forming a spreading rosette around the nut.  ''S. sumatrana'' is closely related to ''S. seminis'' and typically occurs along banks of slow-flowing rivers. The density of the wood is 630-1120 kg/m³at 15% moisture content.