1. Cassia angustifolia (Indian or Tinnevelly Senna) – Indigenous to Arabia, India and Somaliland, it is cultivated in Tamil Nadu, Andhra Pradesh, Gujarat and Rajasthan in India.
2. Cassia acutifolia (Alexandrian Senna or Cassia Senna) – Less commonly collected than Indian senna it is cultivated in Sudan, Egypt and northeast African countries.
3. Plantago ovata – The genus Plantago contains over 200 species with P. ovata and P. psyllium produced commercially in several European countries, the former USSR, Pakistan and India. About 10 species of Plantago are recorded in India of which P. ovata is the most important. Seeds of P. ovata (known as Isabgol, blonde psyllium or plantago seeds) are the largest exported plant drug from India cultivated in Gujarat (Sidhpur), Maharashtra, Punjab and Rajasthan.
4. P. psyllium seeds are called psyllium or flea seeds and are chiefly produced in Spain, France and Cuba. France was the leading producer of Ispaghula from psyllium seeds until 1890. However now India is the leading producer of Ispaghula products. P. arenaria is produced in the Mediterranean Europe and Egypt. Seeds of P. indica and P. afra (known in commerce as Spanish or French psyllium) along with other species of plantago are produced commercially in several European countries, former USSR, Pakistan and India.

Other purgative drugs of erstwhile importance such as aloes, cascara and rhubarb are no longer prescribed as purgatives because of their drastic mode of action and the severe griping that follows. Gums such as acacia, tragacanth, guar gum and sterculia as also other polysaccharide drugs are used as laxatives to a limited extent due their bulk-forming property. Buckthorn resembles cascara in its cathartic action and is commonly used in Europe in the form of a fluid extract.