This is a widespread circumboreal species, or species-complex, with a great range in chromosome number; 2n = 27 to 147. Many variants have been recognized (FNA 24); see also notes under angustifolia. Some plants in northern states and Canada have been considered native (Carrier & Bort 1916, F), and there are clearly native segregates typical of boreal and alpine regions (Stoneberg-Holt 2003). But it remains unclear if any plants occurred in more central to southern states before European settlement. In Ky. pratensis has been widely planted for pasture and lawns since the period of Virginian settlement, using seed derived from Europe, and it prospered on fertile calcareous soils. A common name in Ky. for this species during the early decades of settlement was "English Grass". In Britain, its ecology has been summarized as follows BSBI 2022): "A rhizomatous perennial grass of meadows, pastures, waysides, lawns and amenity grasslands (including sports pitches) and waste places; formerly an important constituent of agricultural seed mixtures, and still used in the sowing of amenity and wild-flower grasslands. It is a versatile grass, preferring well-drained, neutral soils of moderate to high fertility, and tolerant of grazing and trampling. Generally lowland, but with an exceptional record of 1,070 m..."