Phytovation uses the dried seed pods of senna which is a semi-desert plant from a large genus of flowering plants in the legume family Fabaceae. In accordance with the British and European Pharmacopoeias pods sourced from India are from the variety Cassia angustifolia Vahl and pods sourced from Sudan are from the variety Cassia senna L.

Senna has been known and used for its laxative properties since Egyptian times and the word senna is thought to be derived from the Arabic sanā. Senna has been used in western medicine since the middle ages and was typically used by making a tea from a small quantity of leaves or pods. Senna is now mostly presented in tablet form but capsules, granules and liquid presentations are also available in some markets.

The active part of the senna consists of a series of hydroxyanthracene glycosides and related compounds. These are broken down by the gut flora to produce a smaller molecule rhein which then irritates the wall of the large intestine provoking peristaltic action and also the ingress of water to the intestine promoting bowel movement.