20 p. : 26 cm

"At sporadic intervals in the fall the southwestern desert landscape is emblazoned with large, conspicuous, usually orange-colored flowers of the annual Kallstroemia grandiflora (Torrey) Gray. These flowers produce an abundance of pollen and nectar, which is exploited in three ways by insects belonging to 12 different families and 46 species, including bees, wasps, flies and butterflies. The plant is of special interest from the standpoint of pollination ecology, as both the plant and some of the insects have adaptations in behavior that are not always mutually beneficial. The flowers of K. grandiflora are allogamous for most of the daily flowering period and become autogamous as the flowrrs close. Thus, they can be either cross- or self-pollinated, with the former evidently favored. The flowers have little or no odor, a color range within 'bees yellow' (500-650 [microns]), and a strong ultraviolet reflective pattern on both upper- and under-surfaces. Insects are evidently attracted by color and ultraviolet reflection, with the latter so arranged as to form nonreflective, dark target, 'nectar guide' areas on both upper- and under-surfaces. One group of bees and wasps gather pollen and nectar from the top of the flower, effecting both cross- and self-pollination in the process. A second group of smaller bees and wasps gather nectar from within the flower but avoid contact with the sexual portions and are therefore of no importance in pollination. The third group of honeybees and several other larger bees and wasps, extract nectar from the underside of the flower completely avoiding the sexual parts of the plant and therefore play no role in pollination. Even though the plant gains no direct benefit from this last group of insects it nevertheless supplies them with a sepal nectar guide that directs them to the nectaries. It is proposed that these species may be contributing to the economy of the plant by reducing the quantity of available nectar so that the pollinators have to visit more flowers to get their full nectar supply"--P. 3

"Issued September 17, 1974."

Includes bibliographical references (p. 18-20)

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