Cassia fistula (Leguminosae) grows wild and as a roadside tree in India. The leaves and pods of this plant contain the commercially important laxative sennoside B rhein. Both sennoside and rhein contents in the leaves and the pods show seasonal variation. Plants growing at different localities of India have also been found to contain different amount of sennoside B in leaves and pods and also differ in chromosome morphology. No relation between chromosome morphology and sennoside content, however could be established. Although sennoside content in this species is lower than in the official drug senna (C. angustifolia), this plant may be considered as an alternate source of sennoside B.