The American bumble bee (Bombus pensylvanicus), is so named because it occurs throughout North America, from Quebec south to Florida and into Mexico. The American bumble bee is a generalist feeder that forages on plants in the milkweed (Asclepiadaceae), composite (Asteraceae), forget-me-not (Boraginaceae), honey-suckle (Caprifoliaceae), morning-glory (Convolvulaceae), legume (Fabaceae), mint (Lamiaceae), blazing star (Primulaceae), rose (Rosaceae), snapdragon (Scrophulariaceae), and nightshade (Solanaceae) families.
Studies have found the American bumble bee to be a significant pollinator of several plants, including the federally endangered Alabama leather flower (Clematis socialis). These bees visit the Alabama leather flower plants with great frequency resulting in a high single-visit seed set. In the Chihuahuan Desert, the American bumble bee is one of the main pollinators of lechuguilla (Agave lechuguilla) - an indicator species for the Chihuahuan Desert. American bumble bee queens and workers are important pollinators of wavyleaf or pale purple coneflower (Echinacea simulata) and males are the major pollen carriers of tall or rough blazing star (Liatris aspera). Morning glory (Ipomoea purpurea and Ipomoea hederacea) is commonly pollinated by the American bumble bee, as is the yellow fringeless orchid (Platanthera integra). The American bumble bee is also known to forage on tall ironweed ( Veronia gigantea ), red clover (Trifolium pretense), Queen Anne's lace (Daucus carota), and sunflower (Helianthus spp.)
- Close clustering of anthers and stigma in Ipomoea hederacea enhances prezygotic isolation from Ipomoea purpurea, R. A. Smith and M. D. Rausher, New Phytologist, 2006.)
- Conservation Impact of Climatic Variability on Pollination of the Federally Endangered Plant, Clematis socialis (Ranunculaceae), M. A. Wall, M. Timmerman-Erskine, and R. S. Boyd, Southeastern Naturalist, Vol. 2, Issue 1, March 2003, pp. 11-24
- Element Stewardship Abstract for Platanthera integra, Alfred E. Schuyler, State of New Jersey, Department of Environmental Protection and Energy
- Variation and Evolution in Plants and Microorganisms: Toward a New Synthesis 50 Years after Stebbins, F. J. Ayala, W. M. Fitch, and M. T. Clegg, Editors, 2000, National Academy of Sciences