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*A medium-sized to large tree up to 50 m tall with bole up to 145 cm in diameter, buttresses up to 2.5 m high; leaves .*Leaves broadly ovate to suborbicular, thickly leathery, 10-20 cm × 9-16 cm, with 7-9 pairs of secondary veins, glabrous; stamens .*Stamens 15, anthers subglobose, with long, slender appendages, stylopodium indistinct; larger .*Larger fruit calyx lobes up to 16 cm × 3.5 cm.  ''S. pachyphylla'' occurs locally gregariously in mixed peat-swamp forest especially near the coast. The density of the wood is 530-1010 kg/m³at 15% moisture content.