Thai basil is a tropical variety of sweet basil that is distinguished by its purplish stems, reddish purple flower buds and deep green leaves. Thai basil has leaves that are smaller and not as circular as the Western variety. The plant has a characteristic scent of basil mixed with licorice or anise, but it is different from the Western strains of licorice basil or anise basil. Basil is native to India, Southeast Asia and Northern Africa. In herbal medicine, basil is used as a digestive, an antiseptic and an antidepressant.