Recent investigations into the toxicity of known and unknown poisonous plants in the Union of South Africa IX

Abstract

The toxicity of thirty-three plants was investigated. According to the available literature the following ten plants were proved for the first time to be toxic: Lotononis laxa, Cotyledon coruscans, Cotyledon campanulata, Asaemia axillaris, Zygophyllum Morgsana, Urginea sp., Hymenocylus Smithii, Drosanthemum sp. probably D. hispidum, Chironia baccifera and Senecio sp. ab. Kraamwinkel, Settlers, July, 1937. It was also established that Dimorphotheca caulescens and Dichrostachys nyassana contain hydrocyanic acid. It is interesting to note that according to our present knowledge we can divide the poisonous species of cotyledon into three groups according to the symptoms caused by them, viz (A) those species (C. decussata, C. ventricosa, C. obovata, C. Wallichii, etc., containing cotyledontoxin), which cause “Krimpsiekte" (cotyledonosis), (B) those species (C. campanulata) which contain hydrocyanic acid, and (C) those species (C. coruscans) which cause pronounced gastrointestinal irritation (haemorrhagic enteritis). The active principle responsible for the severe irritation is unknown. The species of Cotyledon coruscans tested by us, however, also contained a small quantity of cotyledontoxin, but not in such quantities as to cause ''krimpsiekte''.