... present in Costus speciosus, Smilax menispermoidea, species of Paris, Trigonella, and Trillium, and many species of Dioscorea - D. althaeoides, colletti, futschauensis, gracillima, hispida ... , septemloba, and zingiberensis. Diosgenin is the precursor for the semisynthesis of progesterone which in turn was used in early combined oral ...