A reinvestigation of Kenyan Senecio ruwenzoriensis reported to contain two alkaloids of unknown structures, ruwenine and ruzorine, resulted in the isolation of the pyrrolizidine alkaloid isoline, accompanied by what appeared to be bisline, two alkaloids previously described as constituents of Senecio othonniformis from South Africa. Senecio othonniformis and S. ruwenzoriensis are the same, and it seems highly probably that ruwenine is the alkaloid now known as isoline, while ruzorine may be bisline. © 1992.