Smodingium argutum, the African poison ivy or pain bush,[1] is a southern African shrub or medium-sized tree in the Anacardiaceae, which has properties comparable to the American poison ivy,[2] as its sap contains heptadecyl catechols that are toxic to the skin.[3]
An immuno-chemical reaction is suspected as in other toxic anacardiaceous species.[2] It is monotypic in the genus Smodingium,[2] and was discovered in Pondoland by J. F. Drège during an 1832 expedition with the zoologist Andrew Smith.[2]
It resembles Rhus species in habit and foliage. It is very variable in size, sometimes a woody shrub barely 1–2 feet high, or otherwise a tree of up to 6m. During summer it produces small, creamy green flowers arranged in large sprays.[3] The Greek generic name, meaning "durated mark",[2] alludes to its hard, flattened seeds, which are fitted with papery wings.[3] The margins of the alternately arranged, trifoliolate leaves are toothed, as suggested by its specific name, argutum, which means "sharp".[2] The foliage assumes attractive autumn colours. When damaged the twigs exude a creamy, poisonous sap, which turns black when the catechols contained in it polymerize to a melanin.[2]
It occurs along the Mpumalanga escarpment, the uplands of Eswatini, the KwaZulu-Natal midlands, Pondoland and Transkei, southern Lesotho and the southern Free State.[3]