The zoapatle II--botanical and ecological determinants

A collection of Montanoa (Cerv) specimens was conducted throughout Mexico. Twenty-one specimens were classified, some of them grown in the greenhouse and transplanted in an agricultural experimental field station in the Valley of Mexico. In vitro uterotonic potency was assayed and the results expressed as equivalents of oxytocine, by using estrogenized guinea pig uterine strips. A great variation of uterotonic potency was observed among the wild plants. A clear decrease and uniformity of uterotonic potency was found in plants grown in the experimental field. The study points out the importance of ecological variations in expression of the plant's biological activity.