For example, the discovery of abnormal flowers—for example, flowers with leaves instead of petals, or flowers with staminoid pistils—furnished important evidence for the "foliar theory", the theory that all flower parts are highly specialised leaves.
Étienne Wolff (Auxerre, 12 February 1904 - Paris, 18 November 1996) was a French biologist, specialising in experimental and teratological embryology.