The Breeding Systems of Lupinus, Group Micranthi

Lupinus section Micranthi is a group that contains many small flowered annual lupines and ranges from British Columbia to northern Mexico. They have the characteristic flower of the Pea family, and like many, if not most, of its members are self pollinated to a large degree, because of the floral structure, the keel containing both the stamens and style in close proximity. While studying the taxonomy of this group and growing some of its members for purposes of comparison, it was observed that in the greenhouse flowers of l. bicolor regularly set seed, but that those of L. nanur failed to do so. Were it not for the self pollinating mechanism this might have been attributed to the absence of insects. Preliminary investigation indicated a difference in the way that this mechanism operates and hence a difference in the variation pattern of the two species. The purpose of this investigation is to ascertain and clarify these differences. First the structure of the flower is carefully analyzed and thereafter follows a discussion of the insect relationship and how bees operate the pollination mechanism in L. nanus. Experiments designed to study the rate of floral development, the time of stigma receptivity, and the period of pollen viability are then presented and their bearing on selfing and outcrossing is discussed. I am under obligation to Professor Carl Epling for advice and guidance.