Incipient Domestication of Mustards in Northwest Mexico

The leaves and hypocotyls of mustard (Brassica campestris) are highly prized as fresh and dried edible greens by the Tarahumara Indians of Chihuahua. The plant is collected as a weed in the summer and as a cultivated plant in the fall. The seeds are sown in animal corrals in September in order to produce mostly leaves and swollen hypocotyls; this practice appears to be based on the differences in biomass allocation in the plants under different photoperiods. In addition, the mustard sown plots are said to be less weedy during the following growing season; this may be based on the allelopathic nature of Brassica. Brassica campestris was probably introduced as a weed in wheat seed stock by the missionaries. The Tara humara have begun to domesticate the plant by selecting plants which primarily produce leaves and swollen hypocotyls under short daylight regimes of the fall months. It appears that this mustard may be replacing cultivated Cucurbita in their subsistence diet. The Tarahumara use of Brassica may reflect an extension of food preference for crucifers (such as Lepidium) which are commonly gathered or sown.