Ironwood cassia

Senna siamea, the kassod tree, ironwood cassia or Siamese cassia, is a medium-sized fast-growing evergreen tree of the family Fabaceae, native to Southeast Asia and now widely planted across the tropics for shade, firewood and soil improvement. It typically reaches 15 to 20 metres in height with a short straight trunk to about 30 centimetres in diameter, grey to greyish-brown bark and a dense spreading crown. The leaves are alternate, pinnately compound, 15 to 30 centimetres long, with six to twelve pairs of opposite oblong leaflets that are rounded at both ends, 2 to 7 centimetres long, dark green and glabrous above and slightly paler below. Flowers are produced in large terminal panicles of dense corymbose clusters, each flower bright yellow with five obovate spreading petals about 2 centimetres long, with ten unequal stamens. The fruit is a flat, straight, leathery to woody dark brown pod 15 to 30 centimetres long and 1.5 centimetres wide, conspicuously raised over each seed, splitting tardily to release twenty or more flat dark brown seeds. The heartwood is dense, dark and resistant to termites, accounting for the common name 'ironwood cassia'.