Senna is the dried leaflets of Cassia angustifolia used as a laxative. It is mainly cultivated in parts of India like Tinnevelly, Madurai, and Ramnathpuram. Senna contains anthraquinone glycosides like sennoside A and B which are responsible for its purgative effects by increasing intestinal motility and reducing water absorption. The document details the pharmacognostic features, chemical constituents, extraction methods, uses, and adulterants of senna.