Also known as Ant Bush, senna is a member of the pea family (Fabaceae), which is understandable because it has long thin pods that contain the seeds. Originating from Arabic the word, senna, has been used since medieval times or even earlier for medicinal plants that belong to the large Cassia genus. In the first century Dioscorides used the name Cassia for one of the senna plants but it originated from the Hebrew word qase'ah, which might have referred to an unrelated plant.
Senna has long been known as a laxative, which is an action caused from compounds called anthraquinones that are found in almost the whole plant but are quite concentrated in the seeds. When taken in excess anthraquinones are toxic so any overuse of preparations made from senna should be avoided.
The herb is probably the most ancient herbal remedy still used in Western pharmacy that has mostly synthetic drugs. Laxative products made from senna probably come from different species with common names that reflect their different locations, the most likely being Tinnevelly senna (Cassia angustifolia) and Alexandrian senna (Cassia acutifolia). Other senna plants include Aleppo senna, Mecca senna, Tripoli senna, Senegal senna, and Bombay senna. An exception to this tradition is coffee senna, which is native to the Americas.
Description and Habitat
The herb is an annual, shrubby plant that grows up to two metres high and has pinnate leaves
that are made up of three to five pairs of pointed leaflets that are 3 - 5 centimetres long and ovate. Short sprays of cup-shaped yellow flowers terminate the branches and appear in summer. They are about 2 centimetres across and give way to thin cylindrical pods.
Although it's native to tropical and North America coffee senna can be found well naturalised in waste ground and disturbed areas in many subtropical and tropical areas of the world including Australia where it's mostly confined to the coastal regions of the Northern Territory, northwestern Australia, and Queensland.
Uses and Properties
Dried green pods and leaves are used as laxatives and can be taken in the form of syrups, tinctures or infusions.
Excessive or too frequent doses can cause symptoms of liver damage. There have been reports of senna poisoning cattle. Do not take this herb in cases of abdominal pain of unknown origin, appendicitis, intestinal obstructions, inflammatory bowel disease, or during pregnancy or lactation.
Proprietor, author, and tutor of The Home Herbalist Online Course.