A stately Moreton Bay Chestnut at the Queens Garden, Townsville.

A truely iconic tree of the Australian tropics and subtropics, the Black Bean or the Moreton Bay Chestnut is found in Australia and New Caledonia and is the only species in the genus Castanospermum. It is a stately tree and is now a popular ornamental tree locally and also overseas. The tree is also a source of timber.

The Black Bean is rather non-descript when not in flower. However, a very characteristic (and surprising) cucumber smell is emitted when the twigs are broken. After a while one also learns to recognize the dark glossy alternately-arranged pinnate leaves.

In flower this tree is mistakable, with attractive bunches of large orange pea flowers growing from the large branches (ramiflory) and even stems of the tree. The fruits are produced abundantly and are also very distinctive. These are large brown pods each containing 2 or more large chestnut-like seeds. Aborigines of the region routinely used the seeds of the Black Bean as a food plant. However, freshly collected seeds are extremely toxic and a lengthy process involving grating, leeching and baking was required before the seeds could be eaten.

The Chinese in some southeast Asian countries call the Black Bean the Lucky Bean Plant germinate the large seeds and sell the seedings in small ceramic pots as an auspicious plant during Chinese New Year.