This plant is very variable in size, from a large shrub to a tall tree of more than 15 metres in height. The bark is pale grey and smooth in young trees but becomes darker brown and somewhat flaky in mature specimens. Strychnos henningsii is easily recognized by the simple opposite leaves that have three to five prominent veins arising from their bases (a characteristic feature). The leaves are bright green and glossy. In spring and early summer small yellow flowers are produced along the branches. Flowers are followed by the bright orange glossy fruits. The fruit pulp is edible but the seeds are extremely bitter and poisonous.