I first became aware of the Peanut Butter Cassia (Senna didymobotrya) while I was living in KwaZulu-Natal. It is a very attractive bush which easily stands out thanks to its erect bright yellow flowers. I first identified it from a delightful book, The Wild Flowers of Southern Africa: Natal. A Rambler’s Pocket Guide by Dr. Winnifred G. Wright, which is filled with detailed black-and-white sketches. I used to colour them in once I had identified a plant and so it is that I see that I first noted the Peanut Butter Cassia in the suburb of Lincoln Meade in Pietermaritzburg in April 1973 and growing along the beach at Uvongo in October a year later. In July 2019 it was growing prolifically along the Transkei coast.
The scientific name has an interesting origin: Senna stems from the Arabic sana , a name covering species with leaves and pods that have both cathartic and laxative properties. Then comes didymobotrya which is made up of didymo (in pairs) and botrya (cluster). The common name (one among several) of Peanut Butter Cassia relates to the fact that when crushed, the leaves smell akin to peanut butter.
In those days I had no idea that it has been classified as an invader plant, the origins of which lie in tropical East and Central Africa, from the Congo east to Ethiopia and south to Namibia, Zimbabwe and Mozambique. Given its beauty, it was inevitably imported for ornamental use. The trouble is that the leaves are toxic to both humans and livestock. Given its prolific load of seed pods, it is quick to invade roadsides, wastelands, disturbed areas, urban open space, grasslands, savannas, woodlands and riparian vegetation.
Several of these evergreen shrubs are growing in some wasteland next to one of the schools in town. As pretty as they are:
It would make sense for the municipality to remove them, especially as they fall into the Category 1 section of invasive aliens in KwaZulu-Natal, Mpumalanga, Limpopo and the Eastern Cape.
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