Ammi visnaga is a species of flowering plant in the carrot family known by many common names, including bisnaga, toothpickweed, and khella. It is native to Europe, Asia, and North Africa, but it can be found throughout the world as an introduced species. This is an annual or biennial herb growing from a taproot erect to a maximum height near 80 centimeters. Leaves are up to 20 centimeters long and generally oval to triangular in shape but dissected into many small linear to lance-shaped segments. The inflorescence is a compound umbel of white flowers similar to those of other Apiaceae species. The fruit is a compressed oval-shaped body less than 3 millimeters long. This and other Ammi species are sources of khellin, a diuretic extract. Khella was used in Ancient Egypt as a herbal remedy for renal colic.
Visnagin, which is found in Ammi visnaga, has biological activity as a vasodilator and reduces blood pressure (by inhibiting calcium influx into the cell). Traditionally A.visnaga tea has been used for kidney stones. Tests on rats have been promising. Ancient Egyptian and Indian writings describe vitiligo treated with psoralen-containing plants such as Ammi majus and exposed to sunlight. There have been a number of European research papers investigating this ancient folk use of the plant.