Pollination of Cypripedium plectrochilum (Orchidaceae) by Lasioglossum spp. (Halictidae): the roles of generalist attractants versus restrictive floral architecture

A comprehensive, worldwide treatment of all groups of bees - 1200 genera and subgenera, including more than 16,000 species. In extensive introductory sections, Charles D. Michener examines the evolution of bees from wasps, the relations of the families of bees to one another, the evolution of bees in relation to that of flowering plants, the nesting behaviour of solitary and social bees, and the structure of immature and adult bees. Drawing on these considerations as well as the fossil record, he speculates on the attributes of the protobee, the common ancestor of all bees. He also cites the major literature on bee biology and describes the need for further research on the systematics and natural history of bees, including their importance as pollinators of crops and natural vegetation.