Oplismenus aemulus

A ground-covering grass which can form large colonies to several metres wide, growing to about 0.3 metres tall. It has thin wiry stems which root at some notes.

It has a large natural geographic distribution in NSW, mainly coastal, growing from the Victorian border to the Queensland border, extending into the central tablelands and central and north-western slopes (seems to be absent from the southern and northern tablelands), as far west as Warrumbungle National Park and Mt Kaputar National Park. It extends though all of coastal Queensland to Cape York Peninsula and west to areas west of Rolleston. It extends along the southern parts of eastern Victoria to Melbourne. Occurrences in New Zealand and the Pacific Islands including New Guinea are also recorded. Please note: the Oplismenus genus is currently undergoing revision and all occurrences of this species may fall under O. hirtellus.

(In some habitats, it is hard to determine if it is native to an area or may have blown in from traffic or cultivation in the area).

It tends to be found in sheltered areas such as creeklines and gullies in moist riparian woodland and forests, on sandy to clay soils. It is common in areas such as riparian woodlands in western Sydney.

The family Poaceae is the grass family (any species outside this family should not be referred to as grasses). They are a group that a lot of us place in the “too-hard” basket but here are some simple facts about them: They are one of the largest groups of flowering plants, in the large monocotyledonous group (sedges, lillies, palms and orchids amongst others), with highly modified flowers and reduced perianth parts. Pollen from the anthers is generally wind-blown and is received by the female pistils. It is thought that grasses have evolved to dominate the planet over the last several 100,000 years, due to a general drying and cooling of many terrestrial areas. Hence, we have the grass-prairies of America, Africa and Australia, as well as other areas with a general reduction in vegetation like rainforests. It is worth remembering that humanity relies heavily on the seeds of 3 grass species for food; namely Wheat (*Triticum aestivum), Corn (*Zea mays) and Rice (*Oriza sativa) – not to mention fodder for agricultural meat.

Identification of grasses can be difficult if one is to plunge ‘in-depth’ but many genera can be identified by the appearance of their inflorescences. Different terminology is applied. Petals and sepals do not apply to flowers but rather structures such as glumes which are bracts that generally support the base of ‘spikelets’ (clusters of flowers or single flowers) with flowers generally called “florets”. Florets typically consist of a palea and a lemma (two joined structures which house the stamens and carpels). Florets can be bisexual or unisexual or sterile. In some genera, glumes are absent. Inflorescence structures are generally familiar, i.e. panicles, racemes, spikes etc).

There are a range of habits such as tussocks or clumping grasses (Poa, Themeda, Cymbopogon etc), to large clumping and running bamboos (world’s largest grasses) and stoloniferous grasses – those that creep prostrate over the ground using stolons (eg: turf grasses such as Kikuyu (*Cenchrus clandestinus) and Oplismenus aemulus).

Grasses produce simple leaves, usually made up of a blade and sheath with accompanying parts such as auricles, ligule and collars (where the blade joins the sheath).

Oplismenus spp. have wiry stems with alternate and simple leaves. In this species, leaves (or blades) are to 5 cm long and 20 mm wide, lanceolate in shape and tapering strongly to a fine point, with 10 to 15 fine nerves; with the base of the leaf clasping the stem; mostly mid green to light green in colour; with a series of crinkles or undulations which are distinctive.

The stems of the flowering heads in grasses are called culms. In this species, the spikelets are simply produced at the terminals of leafy stems but these can be referred to as culms; to 0.3 metres tall. Overall, a terminal panicle is produced of separate racemes, each raceme is at right angles to the stem, each one to about 50 mm long by only a few millimetres wide, consisting of spikelets to about 4 mm long. The spikelets are awned at the apex and typically green in colour, sometimes with red and paler tones (awns generally red). Each spikelet contains about 2 florets which eventually ripen to produce seed about 3 mm long.