Vitex agnus-castus is a plant native of the Mediterranean region. It is one of the few temperate-zone species of Vitex, which is on the whole a genus of tropical and subtropical flowering plants. Theophrastus mentioned the shrub several times, as agnos (ἄγνος) in Enquiry into Plants. It has been long believed to be an anaphrodisiac – leading to its name as "chaste tree" – but its effectiveness for such action remains unproven.

Vitex is a genus of flowering plants in the sage family Lamiaceae. It has about 250 species. Common names include chaste tree or chastetree, traditionally referring to V. agnus-castus, but often applied to other species, as well.