Poa sieberiana

Poa sieberiana is a dense tussock grass with green to greyish green leaves which grow to about 50 cm long, with seeds heads to 1 metre tall.

It has a large natural range, growing in NSW, from near coastal areas, growing commonly on the tablelands and western slopes, to the western plains, extending into south-east Queensland and right through Victoria and Tasmania, into the east of South Australia.

It is found often in dry sclerophyll woodland and forests, especially on high rocky slopes but also creeklines and cold valleys.

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 agrciultural 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 prostrately 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). In this species, leaves are fine to very fine, to 0.7 mm wide, straight or curved to flexuous, usually scabrous with very short tooth-like hairs.

The stems of the flowering heads in grasses are called culms. In this species, they are to 1 metre tall. This species has very attractive inflorescences (panicles) which rise well above the foliage and are flexible in nature, from spring through to summer with pale green to purple seed heads.

Grasses mainly produce a grain or caryopsis (there are some cases of berries, nuts and utricles). A grain is a fruit which is basically ‘all seed’ with very little associated tissue and can therefore germinate rapidly. In this species, they are about 1 to 2 mm long with an oval to cylindrical shape.