Family: Poaceae

Status: Listed as a Weed of National Significance (one of Australia’s top 20 weeds).

Description:
A tall grass about 1m high, with mid to dark green leaves up to 5mm wide, held either erect or spreading. Leaves usually flat, or partly in-rolled, and are slightly rough to the touch along the margins. They are strongly ribbed on the upper surface. There are tufts of erect hairs where the leaf blade joins the stem (pulling the leaf blade back from the stem may make these more obvious).
Flowering stems are erect or arching, slightly rough to the touch, with a seed head to 40cm long. The branches of the seed head may be open and drooping, or held close to the stem. The joints (nodes) of the flowering stems are bent, with fine short white hairs on the node, thinning out on the leaf sheath above the node, making the nodes look white compared to the rest of the stem. The seed is sharply pointed and finely hairy at the tip, 6-10mm long, narrowing into a long (40-90mm) awn at the upper end. Each individual seed is enclosed by a pair of reddish-purple glumes, which eventually dry to straw-coloured. The best distinguishing feature is the presence of a collar of short hairs at the point where the long awn attaches to the seed. Most native spear grasses do not have this feature, although they may have a sparse tuft of long hairs in the same position. The awns twist when mature, and may tangle together, causing clumping of the seed heads. When mature and dry, the awns are twice-bent, not uniformly curved.

Preferred habitat and impacts:
Chilean needle grass has not reached the south coast yet, but it has become common in Canberra and Shires to the east and south in recent years, where it has been spread on roadsides and other grassy areas by mowing.
Chilean needle grass is tolerant of a very wide range of soils and conditions, so it has the potential to be very invasive over a large part of the country, in both pasture and native vegetation.

Dispersal:
The seed attaches to animals and clothing, and can be spread in soil, on machinery and vehicles.

Look-alikes:
The native spear grasses (Austrostipa species), of which there are several species on the south coast, can look quite similar. Most native spear grasses found on the coast have narrower leaves, often with the margins in-rolled. Those with broad flat leaves may have the leaf underside with a whitish bloom, which Chilean needle grass does not have. They all have pointy seeds with a long curved or bent awn, and hairy tip, and may appear red before drying to straw colour. However, most do not have the collar of hairs at the seed/awn junction. The seed will need to be grabbed by the awn and pulled free of the enclosing glumes to see the collar of hairs.

Control:
Early detection and removal is vital. Seed is long-lived in the soil and is produced in large quantities, so prevention of seeding is important. Mowing with a catcher mower during flowering will reduce seed set, but the clippings must be burnt. This grass is very unusual in producing some seed hidden within the bases of the flowering stems, so mowing to prevent seeding will be only partially effective. Care would also need to be taken to thoroughly clean the mower before using it anywhere else.
If plants are dug out, they cannot be left to dry out in place because of this production of hidden seed. The whole plant needs to be destroyed. Chilean needle grass will grow and set seed at any time of year. Spraying is best done when plants are actively growing but before they have begun to produce seed. However, identification may be difficult prior to flowering. Non-selective or grass-specific herbicides can be used, but repeat treatment may be needed.
Be very careful if working around seeding infestations not to transport seed attached to clothing or machinery.