Heuchera alba and H. pubescens (Saxifragaceae) are closely related species of alumroot endemic to the Appalachian region of eastern North America that can be difficult to distinguish morphologically. Heuchera pubescens has been understood to occupy a range from Kentucky to Pennsylvania, with the distribution of H. alba restricted to Virginia and West Virginia—plus a recently-recorded extension into Pennsylvania discovered with the help of social media. The uncovering of H. alba in Pennsylvania has challenged historical perceptions of Heuchera distributions in the state, particularly as this relates to the current concept of H. pubescens which may be in need of revision. The present survey of Heuchera conducted in Susquehanna River Valley finds that all previous records of H. pubescens in the valley are instead attributable to H. alba. Additionally, collections of pollinators at these sites beginning in 2019 established the frequent presence of a specialized pollinator, the alumroot cellophane bee (Colletes aestivalis)—the first state record of this bee in Pennsylvania in over a century. Possible reliance of a network of disjunct plant populations in narrowly-defined habitats on an oligolectic bee for pollination services suggests that assessing the population genetics of H. alba in Pennsylvania is an important future step.
