In its strict sense, racemosus has been mapped irregularly across temperate North America (FNA 24), but it is combined here with commutatus. The first reliable records from Ky. appear to date from the 1890s (Gm). Many records are probably referable to commutatus, which has more nodding, spreading panicles and larger spikelet parts but smaller anthers; see Y and FNA 24 for detailed keys. Some authors have suggested combining these species in North America (Hitchcock & Chase 1950, F), but they are generally treated as distinct in Europe. B. commutatus often appears transitional from racemosus (2n = 28) to japonicus (2n = 14), and it may be the most variable of these three taxa (2n = 14, 28, 56). Colls. from BARR and LOGA (KY) are referable to B. commutatus var. apricorum, with distinctly pubescent lemmas. Some depauperate specimens mapped here are difficult to distinguish from japonicus.