Osanyin is the orisha of leaves and of the medicinal knowledge attached to them, and his significance is structural: since Yoruba ritual almost invariably requires plant preparations — washes, infusions, packs, soaps, powders — and since Osanyin owns the leaves, no other orisha's work proceeds without him. He is depicted as radically asymmetrical, with one leg, one arm, one eye and a shrill piping voice, and his emblem is a wrought-iron staff topped with a bird surrounded by smaller birds. The story most often told about him concerns his knowledge being scattered by a wind Oya sent, so that no single person now holds all of it. The practical consequence is that Yoruba herbalism, onisegun practice, and the religious system are one continuous body of knowledge rather than a religion with a folk-medicine annexe — and that the incantation spoken while gathering a leaf is regarded by practitioners as pharmacologically necessary, not decorative.