| Poa pratensis | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Poales |
| Family: | Poaceae |
| Subfamily: | Pooideae |
| Genus: | Poa |
| Species: | P. pratensis |
| Binomial name | |
| Poa pratensis | |
Poa pratensis, commonly known asKentucky bluegrass (orblue grass),smooth meadow-grass, orcommon meadow-grass, is aperennial species ofgrass native to practically all ofEurope,North Asia and the mountains ofAlgeria,Morocco, andTunisia. There is disagreement about its native status inNorth America, with some sources considering it native[3][4][5] and others stating theSpanish Empire brought the seeds of Kentucky bluegrass to theNew World in mixtures with other grasses.[6] It is a common and incredibly popular lawn grass in North America with the species being spread over all of the cool, humid parts of theUnited States. In its native range,Poa pratensis forms a valuable pasture plant, characteristic of well-drained, fertile soil. It is also used for makinglawns inparks andgardens and has established itself as a commoninvasive weed across cool moisttemperate climates like thePacific Northwest and theNortheastern United States. When found on nativegrasslands inCanada, for example, it is considered an unwelcomeexotic plant, and is indicative of a disturbed and degraded landscape.[7][8]
Poa pratensis was one of the many species described byCarl Linnaeus in his landmark workSpecies Plantarum in 1753.Poa isGreek forfodder andpratensis is derived frompratum,Latin formeadow. The name Kentucky bluegrass derives from its flower heads, which are blue when the plant is allowed to grow to its natural height of 60 to 90 cm (2 to 3 feet).[9]
Poa pratensis is thetype species of the grass familyPoaceae.
Five subspecies are accepted.[10]
Poa pratensis is aherbaceous perennial plant 30–70 centimetres (12–28 in) tall. Theleaves have boat-shaped tips, narrowly linear, up to 20 centimetres (8 in) long and 3–5 millimetres (0.12–0.20 in) broad, smooth or slightly roughened, with a rounded to truncate ligule 1–2 millimetres (0.039–0.079 in) long. The conicalpanicle is 5–20 centimetres (2–8 in) long, with 3 to 5 branches in the basal whorls; the ovalspikelets are 3–6 millimetres (0.12–0.24 in) long with 2 to 5florets, 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).
Theligule 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 ofPoa annua andPoa trivialis.
Therootstock is creeping, with runners (rhizomes). The broad, blunt leaves tend to spread at the base, forming close mats.
Poa pratensis is among the food plants of the caterpillars of the meadow brown (Maniola jurtina), gatekeeper (Pyronia tithonus), andpepper-and-salt skipper butterflies; the common sun beetle (Amara aenea) (adults feed on the developing seeds), theleafhopperEupelix cuspidata, the grassbugMyrmus miriformis (feeds on young blades and developing seeds),[11] and the club-horned grasshopper (Aeropedellus clavatus) (feeds on the blades, seeds, and glumes).[12]
Poa pratensis is host to a number offungi, includingClaviceps purpurea, which causesergotism when consumed,Drechslera poae,Epichloë typhina,Phaeoseptoria poae,Puccinia brachypodii var.poae-nemoralis,Stagonospora montagnei,Stagonospora nodorum andWojnowicia hirta.[13]
TheCentral Kentucky Blue Grass Seed Company Building is on the National Register of Historic Places. Since the 1950s and early 1960s, 90% of Kentucky bluegrass seed in the United States has been produced on specialist farms inIdaho,Oregon andWashington.
During the 1990s,[citation needed] botanists began experimenting with hybrids ofPoa pratensis and Texas bluegrass (P. arachnifera), with the goal of creating adrought and heat-resistant lawn grass. In warm climates, such hybrids may remain green year-round.[14]
Bella Bluegrass is a brand-named dwarf variant ofPoa pratentis developed by theUniversity of Nebraska–Lincoln. It has relatively deep roots and propagates relatively rapidly horizontally from its root system but grows to only 2–5 inches (5–13 cm) in above-ground height, basically eliminating the need formowing lawns that use it. It cannot be reproduced by seed and thus depends onsod plugs orsprigging for its production.[15]
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Media related topoa pratensis (category) at Wikimedia Commons
