Strychnos pungens

Strychnos pungens is a tree which belongs to the Loganiaceae. Usually about tall, occurring in mixed woodland or in rocky places. Branches are short and rigid. Leaves are smooth, stiff, opposite, elliptic and with a sharp, spine-like tip. Occurring in South Africa on the Witwatersrand, Magaliesberg and further north to northern Namibia, northern Botswana and Zimbabwe.
The fruit is large, round and with a smooth hard shell, bluish-green in colour and turning yellow when ripe. The pulp of ripe fruit is rich in citric acid and is edible, but the seeds are mildly poisonous. The tree is a close relative of Strychnos nux-vomica, the source of strychnine.