Kentucky Blue grass

Poa pratensis L.

Order: Poales

Family: Poaceae

Names:

Poa
Pratensis
Kentucky Blue grass

Other Names:

Meadow Grass
Meadow Poa
Smooth Stalked Meadow Grass

Summary:

A tufted, perennial, rhizomatous turf grass with a purplish to green seed head.

Description:

Cotyledons:

One.

First Leaves:

Leaves:

Green to grey green.
Blade - Flat or folded, linear, 20-300 mm long x 1-6 mm wide, smooth to slightly rough to touch, abruptly narrowed into a keel or pointed. Hairless or slightly hairy on both sides. Often has a boat shaped tip.
Ligule - Short, 0.2-3 mm long, membranous, flat topped, sometimes jagged. Hairless, rough to touch or tiny hairs.
Auricles - None.
Sheath - Compressed, smooth, lower ones keeled. Usually hairless but the lower leaves are sometimes hairy.

Stems:

Erect, 100-1000 mm tall, slender to stout, smooth, usually round, 2-4 nodes, often bent at the lower nodes. Long runners (rhizomes) bearing scale like leaves and forming a lawn when mown. When unmown it forms tufts. Hairless.

Flower head:

Erect or nodding, dense to open, pyramidal to oblong, green, greyish or purple panicle, 20-200 mm long x 10-120 mm wide. Branches thin, wavy, bare at the base, minutely rough to touch, and often curved and usually 10-50 mm long, in groups of 3-5.

Flowers:

Spikelets - Egg shaped to oblong, swollen, slightly flattened, 2-6 flowered, 2.5-6 mm long, green, pointed tip, smooth on the sides, slightly rough to touch on the top of the keel. Often on a short stalk.
Florets - 2-4 mm long, rounded to slightly pointed.
Glumes - Lower one 1.5-4 mm long, 1-3 nerved, keel rough to touch, hairless. Upper one 2-4.2 mm long, 3-5 nerved, keel rough to touch, hairless.
Palea - Rough to touch on the keels, smooth on the back.
Lemma - Narrowly egg shaped to narrowly oblong, 2-4 mm long, papery, 5 nerved thinly hairy to woolly on the keel and nerves near the edges towards the base. Tip and edges translucent. Basal tuft of long curled hairs between the lemmas. Awnless.
Stamens -
Anthers -

Breaks above the glumes and beneath each floret at maturity.

Seeds:

Small.

Roots:

Slender, creeping or short rhizomes.

Key Characters:

Perennial rhizomatous turf grass.
Short ligule, 0.2-3 mm long, membranous, flat topped and sometimes jagged.
No auricles.
Leaf tips often hooded.

Biology:

Life cycle:

Perennial.

Physiology:

Reproduction:

By seed and rhizomes.

Flowering times:

Spring in western NSW.
October to December in SA.
November and December in Perth.
Spring and summer in WA.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Population Dynamics and Dispersal:

Spread by intentional planting of seed and rhizomes.

Origin and History:

Northern Europe. Europe. Asia.
Introduced to North America.

Distribution:

ACT, NSW, QLD, SA, TAS, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Cool temperate. Mediterranean.

Soil:

Prefers fertile soils in cool, moist areas.

Plant Associations:

Significance:

Beneficial:

Turf grass.
Fodder grass of low productivity in Australia.

Detrimental:

Weed of rotation crops, perennial crops, grass land, river banks and disturbed areas.

Toxicity:

Not recorded as toxic.

Legislation:

None.

Management and Control:

Mowing is ineffective.
It is difficult to manually remove because rhizomes transplant.
A number of grass selective herbicides can provide selective control in broadleaf crops and bush.

Thresholds:

Eradication strategies:

Apply 5 L/ha glyphosate450 in autumn and spring.

Herbicide resistance:

Biological Control:

Related plants:

Annual Poa (Poa annua)
Blue Tussock Grass (Poa poiformis, Poa australis)
Bulbous Poa (Poa bulbosa) is similar but perennial and has swollen pear shaped leaf bases.
Kentucky Bluegrass (Poa pratensis)
Rough Meadow Grass (Poa trivialis) is similar but perennial, stoloniferous, has a longer ligule at 4-10 mm long.
Scaly Poa (Poa fax = Poa lepida)
Snowgrass (Poa sieberiana)
Sweet Swampgrass (Poa fordeana) is very similar and distinguished by the length of spikelet, tip shape and hairiness of the floret and the tip of the leaf.
Tussock grass (Poa labillardieri)

Plants of similar appearance:

Grasses.

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P156.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P29.

Ciba Geigy (1981) Grass Weeds 2. CIBA GEIGY Ltd, Basle, Switzerland. P. Diagrams. P121.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P134-135. Diagram.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P66.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #995.9.

Marchant et al (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P983.

Paterson, J.G. (1977). Grasses in South Western Australia. (Western Australian Department of Agriculture Bulletin 4007). P80-81. Diagram.

Reid, R.L. (1990) The Manual of Australian Agriculture. (Butterworths, Sydney). P252.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.