This alien is fairly widespread in temperate regions of North America, but generally rare in southeastrern states (K, W). The only record from Ky. is a coll. of J. Thieret along railroad tracks in CARR (KNK). R. patientia is close to crispus, and hybrids are known elsewhere; 2n = 60 in both (Cr, FNA 5). There may also be confusion with obtusifolius.