Poa pratensis

Poa pratensis
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
(unranked):	Commelinids
Order:	Poales
Family:	Poaceae
Genus:	Poa
Species:	P. pratensis
Binomial name
	Poa pratensis; L.

Poa pratensis, commonly known as Kentucky bluegrass, smooth meadow-grass, or common meadow-grass, is a perennial species of grass native to Europe, Asia, North America, and northern Africa.

General description

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 northeastern United States. Poa is Greek for fodder.

The name Kentucky Bluegrass derives from its flower heads, which are blue when the plant is allowed to grow to its natural height of two to three feet.^[1]

The rootstock is creeping, with runners (rhizomes). The broad, blunt leaves tend to spread at the base, forming close mats.

Poa pratensis is a herbaceous perennial plant 30–70 centimetres (12–28 in) tall. The leaves 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 conical panicle is 5–20 centimetres (2–8 in) long, with 3 to 5 branches in the basal whorls; the oval spikelets are 3–6 millimetres (0.12–0.24 in) 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 compared to the apple green color of poa annua and poa trivialis.

Poa pratensis is the type species of the grass family Poaceae.

There are two ill-defined subspecies:

Poa pratensis ssp. pratensis – temperate regions
Poa pratensis ssp. colpodea – Arctic

Wildlife value

This species is amongst the foodplants of the caterpillars of the Meadow Brown (Maniola jurtina) and Gatekeeper (Pyronia tithonus) 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).^[2]

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.

Cultivars

Bella Bluegrass

Bella Bluegrass is a cultivar produced through the breeding program at the University of Nebraska. It is unique among bluegrasses for its vegetative reproduction, slow growth habit, a short leaf.^[3]

Midnight

Very dark green, compact growth habit. 'Midnight' has stood out in National Turfgrass Evaluation Program trials for 20 years. It has the distinction of heading it's own class of compact-type hybrid bluegrasses known as 'Midnight-type' (crosses with 'Midnight' as a parent).

Hybridization with Poa arachnifera

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.

References

Notes

^ Published: June 03, 1993 (1993-06-03). "What Makes Kentucky's Bluegrass Blue – New York Times – June 3, 1993". Query.nytimes.com. Retrieved 2012-12-23.{{cite web}}: CS1 maint: numeric names: authors list (link)
^ Natural England description on website
^ Shearman; Robert C. ; et al. "US Patent Application Poa pratensis L. named 'NE-KYB-05-001'". US Patent Office. Retrieved 27 March 2013. {{cite web}}: Explicit use of et al. in: |last= (help)CS1 maint: multiple names: authors list (link)