0 Yam, wild yam ( Dioscorea villosa )

Wild yam is a vine with a tuberous rootstock that is native to North America. Its roots yield an alkaloid which is a muscle relaxant, and it was used to treat abdominal cramps and bilious colic's during the American civil war. Wild Yam is believed to be helpful to the liver and endocrine system. It regulates the female system, particularly during menstrual distress and menopause,as well as used in treating infertility. Used with chaste berry and dandelion it is an effective treatment for morning sickness[citation. 
In a study carried out on a four year period, wild yam was found to be an effective oral contraceptive, but without the side effects of the pill.
One particular species of wild yam, D,vitata has been found to contain up to 40% diosgenin,a glycoside that can easily be converted to the hormone  progesterone.