Senna siamea 铁刀木

Senna siamea (Thai:ขี้เหล็ก, khilek), also known as Siamese cassia, kassod tree, cassod tree and Cassia tree, is a legume in the subfamily Caesalpinioideae. It is native to South and Southeast Asia, although its exact origin is unknown.

It is a medium-size, evergreen tree growing up to 18 m with beautiful yellow flowers. It is often used as shade tree in cocoa, coffee and tea plantations. In Thailand it is the provincial tree of Chaiyaphum Province and some places in the country are named after it.