This is widespread in seasonally wet base-rich soils across temperate regions of North America, but virtually absent on the southeastern Coastal Plain, where it is replaced by the closely related species, dichotomus. It is less tolerant of frequent disturbance than tenuis, but often occurs along scoured rocky banks of streams and rivers. Compared to others in the tenuis group, dudleyi is diagnosed by its short glossy yellowish-brown leathery auricles (versus pale papery), relatively blunt bracteoles, perianth ca. 4-6 mm (less in most other taxa), and longer anthers (ca. 0.6-1 mm versus 0.4-0.6 mm).