11. Another plant that contains substances readily convertible to progesterone is " Dioscorea pseudojaponica " native to Taiwan. 12. You are referring to the air potato, " Dioscorea bulbifera ", a native of the tropics. 13. Among the more notable of these are " Dioscorea villosa " and " Dioscorea polygonoides ". 14. Among the more notable of these are " Dioscorea villosa " and " Dioscorea polygonoides ". 15. In Japan, this species is sometimes mistakenly called Japanese mountain yam, which refers to the native Dioscorea japonica. 16. "Dioscorea mexicana " ranges from the state of San Luis Potos?in northeastern Mexico south to Panama. 17. Figure 2 : Major synthetic steps leading to dioscorine from trigonelline precursor in "'Dioscorea hispida "' 18. Many other " Dioscorea " species of the yam family contain steroidal substances from which progesterone can be produced. 19. "Dioscorea floridana " is a perennial vine twining over other vegetation and spreading by means of yellow underground rhizomes. 20. Yams are in the genus Dioscorea and are an important food source in the tropics but are seldom grown in the United States.
