Kaakmachi or Black nightshade (Solanum nigrum, family: Solanaceae) is a perennial herb with soft stem and many branches. It is native to Eurasia and introduced to the tropical and sub-tropical regions of the world.
Fruit is a berry, smooth, 5-7 cm in diametre; green and bitter when raw and black or purplish black. In Bangladesh and Indian subcontinent another variety is found with berries that turn yellowish red when ripe. Ripe berries are attractive but poisonous.