This is a variable species with a broad northern range; 2n = 56 to 68 (FNA 23). The colls. from CART (MDKY), ELLI (APSC), FLOY (EKY) and elsewhere may be referable to var. condensa Fern., which is not recognized in recent treatments, but has been reported widely from northeastern regions (F). Sterile hybrids with alata, straminea and other species have been documented in other states (FNA 23).