This is widespread across cool temperate regions of North America. It has often been confused with connata or tripartita, and all three taxa have been combined to various extents by some authors (e.g. FNA 21, Y). B. comosa appears to be much more common in Ky. than the other two taxa, but further revision is desirable. In its broad circumboreal sense tripartita includes a range of chromosome numbers (2n = 24, 48, 60; Y). Cr indicated that comosa is at least partly diploid (2n = 24), but FNA 21 stated that North American plants within the tripartita complex are all tetraploids (2n = 48).