Mapping is provisional; deeper revision is needed, including careful attention to types (Wagner 2014; W). Typical tetragona is a taxon of dry or damp woods and edges in northeastern states and Appalachian uplands. In Ky., the few records are mostly clustered along the western edge of the Appalachian Plateaus. Typical tetragona is close to glauca (= fraseri) but with flowers usually smaller (petals 12-25 mm long versus 20-35 mm), and leaves narrower (ca. 5-10 mm wide versus 10-30 mm). There may be some intergradation, but in Ky. most or all material that has been named tetragona appears closer to glauca. B's records of tetragona are mostly grouped here with glauca; those of Munz (1937, 1965) still need to be reexamined. There is an obscure 1836 coll. of what seems to be typical tetragona by C.W. Short (GH), apparently sent from Ky., with a note: "Oenothera fraseri/fruticosa? I am most perplexed by this genus. Have you any well-determined species in Florida?" A few colls. from CART (KNK), EDMO (APSC, US), FLEM (EKY), LEWI (APSC, NCU) and MADI (BEREA) may also be referable to typical tetragona. Some plants from Appalachian riverbanks, especially the Big South Fork (MCRE), can key to O. tetragona var. longistipata (Pennell) Munz, a poorly understood taxon that appears to be at least transitional from typical tetragona to brevistipata (Munz 1937; F). Plants known as O. tetragona var. hybrida (Michx.) Fern and var. latifolia (Rydb.) Fern. may be transitional to O glauca; they have similar ranges to glauca, largely Appalachian but perhaps concentrated at higher elevation (F).