Poaceae

MONOCOTYLEDONS

POACEAE - Grass Family

A very large, cosmopolitan family with over 8000 species. In Western Australia there are approximately 400 native and 200 naturalised species. The flowers are inconspicuous and the inflorescence usually consists of groups of flowers called spikelets. There are no petals or sepals as such, instead the reproductive organs are enclosed in two green structures called the lemma and the palea. Sterile structures called glumes are also produced at the base of the spikelet (see diagram).

Because of the small flowers, it is often difficult to identify grasses with certainty. Also, in addition to the naturalised species given here, many of the genera include native species. Specialist texts should be consulted for exact identification.
Agrostiscapillaris (brown top bent) is a rhizomatous perennial to 70cm tall. The leaves are flat, glabrous and the flowers are produced in summer. An occasional weed in higher rainfall areas on road verges and in pastures. Native to Eurasia. A. gigantea (red top bent) is similar to the preceding species but is more robust and taller (to 1.5m) with broader leaves. A rarely recorded weed of pastures and wasteland. Native to Eurasia. A. stolonifera (creeping bent) is also similar to A. capillaris but has leafy stolons, not rhizomes, and a dense inflorescence. Used as a turf grass; found on wasteland, road verges and pastures. All found between Pemberton and Albany. Native to Eurasia and North America.

Aira (hairgrasses). Although four species are recorded from Western Australia, plants from many populations are impossible to ascribe to these species, as intermediates are very common. The description applies to all species recorded, namely, A. caryophyllea (silvery hairgrass), A. cupaniana,A. elegantissima and A. praecox (early hairgrass). All are delicate annuals, to 30cm tall, but usually smaller. The inflorescence is open, ovoid, much branched, the individual spikelets tiny and the lemma has one or two awns. The leaves are apparently glabrous, to 8mm long and 1mm wide. These grasses are very common (often abundant) weeds of pastures on poor soils and many types of bushland in southern Western Australia. All are native to Europe. (Aira can be confused with Pentaschistis - check the ligule, in Aira it is a clear semi-transparent membrane, in Pentaschistis it is a fringe of hairs.)

Aira caryophyllea, RR

Alopecurus geniculatus (foxtail) is a tufted slender annual or perennial, rooting at the nodes, growing to 60cm tall. The inflorescence is cylindrical, dense and 2-12cm long. The lemmas are awned and the leaves are flat and 2-8mm wide. A weed of woodlands in the Goldfields. Native to Eurasia.
A. myosuroides (blackgrass, slender foxtail) is an annual, with glumes united for more than a third of their length. It is an uncommon weed of wetlands from Gingin to Perth. Native to Europe, Asia and North America.
A. pratensis (meadow foxtail) is similar to A. geniculatus but is a perennial. It is an uncommon weed of urban bushland and wetlands around Perth, but it also occurs as a pasture grass in the lower south-west. Native to Europe. All flower in spring.

Alopecurus pratensis , CG

Ammophila arenaria (marram grass) is a densely tufted, rhizomatous perennial to 1.3m tall. The inflorescence is erect, dense, spike-like and cylindrical, pale green to straw-coloured. The leaves are grey-green, stiff and tough with strongly inrolled margins. It has been extensively planted as a sand binder on beaches between Perth and Bremer Bay and has become naturalised, flowering in spring and early summer. Native to Europe.

Ammophila arenaria , GK

Andropogon distachyos is a tufted perennial to 1.5m. It is a roadside weed beginning to invade woodlands in the Darling Range near Perth. Flowers in spring, native to Africa. A. gayanus (gamba grass) is a robust tufted perennial to 4m. The stems and leaves are hairy. The inflorescences are held above the leaves and consist of loosely-branched, hairy spikelets, each composed of two finger like projections. Flowering from March to July, along road verges and in pastures. A native to tropical Africa, it has been introduced as a pasture grass to Kununurra, and is likely to naturalise. It is regarded as a serious threat to savanna woodlands in the Northern Territory since it forms dense monospecific stands and generates very hot fires.

Andropogon distachyos , RR

Anthoxanthum odoratum (sweet vernal grass) is a tufted perennial, sweetly scented by coumarin, to 50cm, with flat, glabrous or hairy leaves to 20cm long. The inflorescence is a dense, green, spike-like panicle. Flowers in late spring and early summer, a common weed of disturbed wetlands, road verges and pastures throughout the south-west. Native to Europe and temperate Asia.
Arrhenatherum elatius var. bulbosum(bulbous oatgrass, onion couch) is a slender tufted perennial to 50cm tall with swollen and corm-like stem bases. The leaves are flat and either hairy or glabrous. The inflorescence is a loose, nodding panicle. Native of Europe and the Mediterranean region, introduced as a pasture grass, now sparingly naturalised in the higher rainfall areas between Pemberton and Albany.

Anthoxanthum odoratum , RC

Arundo donax (giant reed, sometimes incorrectly called bamboo) is a robust perennial with woody stems to 6m tall, growing from a stout, creeping rhizome. The leaves are evenly spaced along the stem in two rows. The inflorescence is a large, fluffy panicle, dense and erect to 60cm long, produced in summer. It is a garden escape forming suckering clones around old settlements on roadsides, creeklines, wetlands and wasteland from Geraldton to Albany. Very common around Perth, where variegated leaf clones (var. versicolor) are frequent. A native of southern Europe and Asia.

Arundo donax , RR

Avellinia michelii is a tufted annual to 30cm with flat, hairy leaves to 30mm long. The inflorescence is a contracted panicle. Flowers in spring. This species is a very widespread weed of wetlands and woodlands throughout southern Western Australia; it appears to replace the similar Rostraria pumilia, which is the arid zone equivalent. A native of the Mediterranean region.

Avellinia michelii , CG

Poaceae continued

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*Aira* (hairgrasses). Although four species are recorded from Western Australia, plants from many populations are impossible to ascribe to these species, as intermediates are very common. The description applies to all species recorded, namely, *A. caryophyllea* (silvery hairgrass), *A. cupaniana,A. elegantissima* and *A. praecox* (early hairgrass). All are delicate annuals, to 30cm tall, but usually smaller. The inflorescence is open, ovoid, much branched, the individual spikelets tiny and the lemma has one or two awns. The leaves are apparently glabrous, to 8mm long and 1mm wide. These grasses are very common (often abundant) weeds of pastures on poor soils and many types of bushland in southern Western Australia. All are native to Europe. (Aira can be confused with Pentaschistis - check the ligule, in Aira it is a clear semi-transparent membrane, in Pentaschistis it is a fringe of hairs.)	*Aira caryophyllea*, RR
*Alopecurus geniculatus* (foxtail) is a tufted slender annual or perennial, rooting at the nodes, growing to 60cm tall. The inflorescence is cylindrical, dense and 2-12cm long. The lemmas are awned and the leaves are flat and 2-8mm wide. A weed of woodlands in the Goldfields. Native to Eurasia. *A. myosuroides* (blackgrass, slender foxtail) is an annual, with glumes united for more than a third of their length. It is an uncommon weed of wetlands from Gingin to Perth. Native to Europe, Asia and North America. *A. pratensis* (meadow foxtail) is similar to A. geniculatus but is a perennial. It is an uncommon weed of urban bushland and wetlands around Perth, but it also occurs as a pasture grass in the lower south-west. Native to Europe. All flower in spring.	*Alopecurus pratensis* , CG
*Ammophila arenaria* (marram grass) is a densely tufted, rhizomatous perennial to 1.3m tall. The inflorescence is erect, dense, spike-like and cylindrical, pale green to straw-coloured. The leaves are grey-green, stiff and tough with strongly inrolled margins. It has been extensively planted as a sand binder on beaches between Perth and Bremer Bay and has become naturalised, flowering in spring and early summer. Native to Europe.	*Ammophila arenaria* , GK
*Andropogon distachyos* is a tufted perennial to 1.5m. It is a roadside weed beginning to invade woodlands in the Darling Range near Perth. Flowers in spring, native to Africa. *A. gayanus* (gamba grass) is a robust tufted perennial to 4m. The stems and leaves are hairy. The inflorescences are held above the leaves and consist of loosely-branched, hairy spikelets, each composed of two finger like projections. Flowering from March to July, along road verges and in pastures. A native to tropical Africa, it has been introduced as a pasture grass to Kununurra, and is likely to naturalise. It is regarded as a serious threat to savanna woodlands in the Northern Territory since it forms dense monospecific stands and generates very hot fires.	*Andropogon distachyos* , RR
*Anthoxanthum odoratum* (sweet vernal grass) is a tufted perennial, sweetly scented by coumarin, to 50cm, with flat, glabrous or hairy leaves to 20cm long. The inflorescence is a dense, green, spike-like panicle. Flowers in late spring and early summer, a common weed of disturbed wetlands, road verges and pastures throughout the south-west. Native to Europe and temperate Asia. *Arrhenatherum elatius* var. *bulbosum*(bulbous oatgrass, onion couch) is a slender tufted perennial to 50cm tall with swollen and corm-like stem bases. The leaves are flat and either hairy or glabrous. The inflorescence is a loose, nodding panicle. Native of Europe and the Mediterranean region, introduced as a pasture grass, now sparingly naturalised in the higher rainfall areas between Pemberton and Albany.	*Anthoxanthum odoratum* , RC
*Arundo donax* (giant reed, sometimes incorrectly called bamboo) is a robust perennial with woody stems to 6m tall, growing from a stout, creeping rhizome. The leaves are evenly spaced along the stem in two rows. The inflorescence is a large, fluffy panicle, dense and erect to 60cm long, produced in summer. It is a garden escape forming suckering clones around old settlements on roadsides, creeklines, wetlands and wasteland from Geraldton to Albany. Very common around Perth, where variegated leaf clones (var. *versicolor*) are frequent. A native of southern Europe and Asia.	*Arundo donax* , RR
*Avellinia michelii* is a tufted annual to 30cm with flat, hairy leaves to 30mm long. The inflorescence is a contracted panicle. Flowers in spring. This species is a very widespread weed of wetlands and woodlands throughout southern Western Australia; it appears to replace the similar Rostraria pumilia, which is the arid zone equivalent. A native of the Mediterranean region.	*Avellinia michelii* , CG