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''Poa pratensis'', commonly known as Kentucky bluegrass (or blue grass), smooth meadow-grass, or common meadow-grass, is a perennial species of grass native to practically all of Europe, North Asia and the mountains of Algeria and Morocco. Although the species is spread over all of the cool, humid parts of the United States, it is not native to North America. The Spanish Empire brought the seeds of Kentucky bluegrass to the New World in mixtures with other grasses. ''Poa pratensis'' forms a valuable pasture plant, characteristic of well-drained, fertile soil. It is also used for making lawns in parks and gardens and is common in cool moist climates like the Pacific Northwest, and Northeastern United States. When found on native grasslands in Canada, however, it is considered an unwelcome exotic plant, and is indicative of a disturbed and degraded landscape.

Taxonomy

''Poa pratensis'' was one of the many species described by Carl Linnaeus in his landmark work ''Species Plantarum'' in 1753. ''Poa'' is Greek for fodder and ''pratensis'' is derived from ''pratum'', the Latin for meadow. The name Kentucky bluegrass derives from its flower heads, which are blue when the plant is allowed to grow to its natural height of . ''Poa pratensis'' is the type species of the grass family Poaceae. There are two ill-defined subspecies: *''Poa pratensis'' subsp. ''pratensis'' – temperate regions *''Poa pratensis'' subsp. ''colpodea'' – Arctic

Description

''Poa pratensis'' is a herbaceous perennial plant tall. The leaves have boat-shaped tips, narrowly linear, up to long and broad, smooth or slightly roughened, with a rounded to truncate ligule long. The conical panicle is long, with 3 to 5 branches in the basal whorls; the oval spikelets are long with 2 to 5 florets, and are purplish-green or grey. They are in flower from May to July, compared to annual meadowgrass (''Poa annua'') which is in flower for eight months of the year. ''Poa pratensis'' has a fairly prominent mid-vein (center of the blade). The ligule is extremely short and square-ended, making a contrast with annual meadowgrass (''Poa annua'') and rough meadowgrass (''Poa trivialis'') in which it is silvery and pointed. The Kentucky bluegrass is a dark green/blue compared to the apple-green color of ''Poa annua'' and ''Poa trivialis''. The rootstock is creeping, with runners (rhizomes). The broad, blunt leaves tend to spread at the base, forming close mats.

Ecology

This species is among the food plants of the caterpillars of the meadow brown (''Maniola jurtina''), gatekeeper (''Pyronia tithonus''), and pepper-and-salt skipper butterflies; the common sun beetle (''Amara aenea'') (adults feed on the developing seeds), ''Eupelix cuspidata'' of the leafhopper family, and ''Myrmus miriformis'', a grassbug (feeds on young blades and developing seeds).Natural England description on website


Cultivation and production

Since the 1950s and early 1960s, 90% of Kentucky bluegrass seed in the United States has been produced on specialist farms in Idaho, Oregon and Washington. During the 1990s botanists began experimenting with hybrids of ''Poa pratensis'' and Texas bluegrass (''P. arachnifera''), with the goal of creating a drought and heat-resistant lawn grass. It is famously used for the playing field of Lambeau Field in Green Bay, WI and is sown into the field for reinforcement.


Gallery


File:Poa pratensis (Billeder af nordens flora 1917ff., v2 0383) clean, no-description.jpg File:Poa pratensis (3883809159).jpg File:Poa pratensis plant1 (7398746202).jpg File:Poa pratensis sl6.jpg File:Poa pratensis detail.jpeg|Closeup of flowers File:Poa pratensis sl19.jpg File:Poa pratensis sl12.jpg File:Poa pratensis seeds 20101113.jpg

References



Notes



Further reading


Flora Europaea: ''Poa pratensis''European ''Poa'' DatabaseHorticultural information on this turfgrass; growing it in the home garden
* ''The Observers Book of Grasses, Sedges and Rushes''. Frances Rose. pages 42–43
Kew gardens grass database
{{Authority control pratensis Category:Lawn grasses Category:Grasses of Africa Category:Grasses of Asia Category:Grasses of Europe Category:Grasses of North America Category:Grasses of Canada Category:Grasses of the United States Category:Cosmopolitan species Category:Plants described in 1753 Category:Taxa named by Carl Linnaeus