Article

Pollination ecology was studied in Lupinus pilosus with respect to floral colour change. Whitephase banner-spot flowers offered more pollen as reward to foraging pollinators than purplephase flowers did. The changes in colour and rcward were recognized by the pollinators. They preferred pre-change flowers and avoided post-change ones. The change in the banner spot from white to purple was enhanced by pollination. Pollination cxperiments indicate that shortage in resources rather than in pollination was thc limiting factor for fruit set, especially in the upper flower whorls.