Kentucky bluegrass

Kentucky Bluegrass
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, known as Smooth Meadow-grass, Common Meadow Grass or Kentucky Bluegrass, is a perennial species of grass native to Europe, Asia, northern Africa and North America.

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. 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]

stem and leaf base detail. The ligule is extremely short and square ended

The rootstock is creeping, with runners. 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.

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.

Poa compressa is a similar species.

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/early-1960s 90% of Kentucky Bluegrass seed has been produced on specialist farms in Idaho, Oregon and Washington.

It is commonly named by farmers in the UK as sweet grass because of its high nutritive qualities.^{[citation needed]}

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-resistant lawn grass.

Illustrations

Poa pratensis

Poa pratensis and Poa trivialis

Photos

	The ligule is extremely short and square ended.		Photo by Kristian Peters
Photo by Kristian Peters	Photo by Kristian Peters	Photo by Kristian Peters
			with rust (Puccinia poae-nemoralis)

References

• Flora Europaea: Poa pratensis

Wikimedia Commons has media related to: Poa pratensis

• European Poa Database
• Horticultural 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