Physostigma coriaceum

Physostigma coriaceum is a woody climbing legume related to the Calabar bean, native to tropical West Africa. The genus Physostigma contains a small number of species, some of which produce seeds containing the alkaloid physostigmine, a potent acetylcholinesterase inhibitor with both toxic and medicinal properties. This species has thick, leathery leaves as its epithet suggests, growing in humid tropical forests.