Hairgrass

Aira species

Aira caryophyllea L. Silvery Hairgrass
Aira cupaniana Guss. Silvery Hairgrass
Aira elegantissima Schur
Aira praecox L. Early Hairgrass

Family: Poaceae.

Names:

Aira is the Greek name for darnel.
Hairgrass or Delicate Hair grass, because of its delicate nature and fine hair like stems and seed heads.

Other Names:

Delicate Hair grass
Early Hair grass
Silvery hair grass, Seed heads are silvery in appearance.

Summary:

A fine leaved, hairless, erect annual grass.

Description:

Cotyledons:

One. Fine.

First leaves:

Parallel sided. Narrow.

Leaves:

Emerging leaf rolled in the bud.
Mainly at the base of the stem.
Blade - Grey green. Hairless. Short. Narrow. Sometimes rolled inwards.
Ligule - Conspicuous, membranous or translucent, lance shaped, hairless.
Auricles - None.
Sheath - Smooth or rough to touch. Loose. Striped

Stems:

100-300 mm tall. Single or a tuft of erect stems.

Flower head:

Loose, open panicle. 20-100 mm long. Broadly egg shaped. Branches longer than spikelets. Often with paired slender branches that are initially erect and later widely spreading.

Flowers:

Spikelets - Single at the ends of fine branches. Silvery or pinkish. 1.5-4 mm long. Spikelet stalks 2-10 mm long. 2 flowered. Flattened.
Florets - 2. Both bisexual. Shorter than glumes. Serrated on the keel.
Glumes - 2, oval, persistent, hairless, membranous, keeled, 1 nerved and pointed.
Palea - 2 lobed.
Lemma - brown, hard, thin and transparent, with a two pointed tip, shorter and narrower than glume and sometimes with a bent awn attached to their back. Rough to touch near the top.
Stamens -
Anthers -

Fruit:

Seeds:

Small. Narrow. Grooved lengthwise on one side.

Roots:

Fibrous.

Key Characters:

Open and lax panicle.
Pedicels (flower stalks) 3-5 times as long as spikelets.

Biology

Life cycle:

Germinates in autumn and early winter following rains. Vegetative growth during winter. Sets seed in spring and dies in summer.

Physiology:

Reproduction:

Flowering times:

September to December.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Origin and History:

Mediterranean. Europe. Africa. Asia. Azores

Distribution:

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

Red = Aira caryophyllea L. Silvery Hairgrass
Yellow = Aira cupaniana Guss. Silvery Hairgrass
Blue = Aira elegantissima Schur
White = Aira praecox L. Early Hairgrass

Habitats:

Grasslands.

Climate:

Temperate

Soil:

Gravelly hill slopes and ridges with sandy granitic or skeletal soils

Plant Associations:

Grasses. white cypress pine communities.

Significance:

Beneficial:

Fodder, but doesn't produce much bulk.

Detrimental:

Weed of grasslands.

Toxicity:

None reported.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Herbicide resistance:

None reported.

Biological Control:

Related plants:

Early Hair grass (Aira praecox)
Delicate Hair grass (Aira elegantissima, Aira elegans)
Silvery Hair grass (Aira caryophyllea, Aira cupaniana)
Plants of similar appearance: 
References:

Black, J.M. (1978). Flora of South Australia. (Government Printer, Adelaide, South Australia). P161. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P34-37. Diagram.

Ciba Geigy 2 .

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P52. Photo.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #41.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P935.

Acknowledgments:

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