. . . . . . . . . "Bombus pensylvanicus" . . "Cephalanthus occidentalis" . . "Richard Barnes. 2017. Bombus pensylvanicus nectar plant Cephalanthus occidentalis. iNaturalist.org. Accessed at <https://www.inaturalist.org/observations/7108614> on 05 Apr 2018." . . . . "http://iNaturalist.org is a place where you can record what you see in nature, meet other nature lovers, and learn about the natural world." .