Until recently (FNA 21), this widespread eastern diploid (2n = 24) has been known incorrectly as B. coronata (L.) Britt. A few colls.from Ky. (B) have been referred to the northern var. tenuiloba (Gray) Sherff, but segregates have not been recognized in recent treatments. There has been occasional confusion with depauperate plants of aristosa, and some colls. should be rechecked. B. trichosperma differs from aristosa and polylepis as follows (F, FNA 21, Y): fruits with L/W mostly 2.5-5 (versus 1.5-2.5), narrowly wedge-shaped to oblong-oblanceolate or nearly linear (versus wedge-shaped to obovate), with indistinct glabrous or merely strigose-ciliolate margins except towards summit (versus with distinct thin friable hispid-ciltate margins) ; disc florets with corollas 3-5 mm long (versus 2-3.5 mm). The whole "aristosa complex" needs deeper revision; it also includes B. aurea (Ait.) Sherff, a Central American species with a perennial white-rayed form that is widely grown in western Europe but apparently not hardy in most of eastern North America (e.g. www.botanic.cam.ac.uk).