Name:
Chilean needle grass(Nassella neesiana)
Description:
Chilean Needle Grass (Nassella neesiana), named for its sharp, pointed seeds, is a perennial tussockforming
grass that grows in dense clumps to 1.2 m in height. The adult plant is long-lived and very
hardy. Its leaves are flat to somewhat inrolled, to 30 cm long and 5 mm wide, strongly ribbed on their
upper surface, sometimes sparsely hairy, and with edges that are rough to touch (particularly in one
direction) due to marginal hairs.
Chilean Needle Grass is unusual in producing two types of seeds: besides the normal flower seeds
produced in a paniculate seed head, it produces hidden seeds in the nodes (swellings along the
stems that give rise to leaves) and bases of the flowering stems. These ‘stem seeds’ are
self-fertilised and account for about one-quarter of total seed production. They enable the plant to
reproduce despite grazing, slashing and fire. The flowering seed heads are loosely
branched, open panicles to 40 cm long with a distinctive purplish colour. The seeds which are up to 1
cm long have a sharp hard point at the base with silky hairs. The 4-9 cm long awn is twisted towards
the base and often bent two or three times. The awns often form a tangled mass at maturity. At the
junction of the awn and the lemma, there is a characteristic raised crown 1 to 1.5 mm long with small
teeth.
For further information and assistance with identification of Chilean Needle Grass contact the
herbarium in your state or territory.
Distribution:
In Australia, Chilean Needle Grass grows in temperate regions with annual rainfall greater than 500
mm. Its known range extends from the Northern Tablelands of New South Wales, along the Great
Divide and through Victoria to south-eastern South Australia. It is well established in large areas of
New South Wales, the Australian Capital Territory and Victoria. Isolated infestations have been
recorded in South Australia, southern Tasmania and the Darling Downs Region of southern
Queensland.
It has been eradicated from the one known site in Tasmania, in Hobart, and this site is subject to
ongoing monitoring. Records in South Australia include near Bundaleer and Lucindale, in the Northern and Southern Lofty regions, respectively.
Based on climatic requirements, Chilean Needle Grass could expand its range and invade grasslands
throughout much of south-eastern Australia, especially south-eastern Queensland, and reach new
areas such as south-western Western Australia.
It is also naturalised and often a weed in Europe, the Americas, South Africa and New Zealand.
Habit:
Grass
Key points:
- Chilean Needle Grass (Nassella neesiana) is a tussock grass highly invasive in native grasslands.
- It builds up a large and persistent seedbank in the soil, thanks to its abundant aerial, basal and stem seeds.
- Rehabilitation of infested land is very difficult.
- For best results, combine herbicide application with physical removal, crop rotation, pasture sowing and grazing management (short duration, high intensity).
How it spreads:
Depending on availability of moisture, Chilean Needle Grass can produce more than 20 000 seeds per square metre. The resulting seedbank can persist for many years even if further seed input is prevented. The seeds are very effectively spread on farm machinery, clothing or livestock. Seed has also been spread along roadsides and other grassy areas by mowing and earthmoving equipment.Floodwater will move seed downstream.
Where it grows:
Chilean Needle Grass grows in temperate regions with annual rainfall greater than 500 mm. It can thrive in a wide range of soils and conditions and has the potential to be very invasive over a large part of the country in both pasture and native vegetation. Although it occurs mainly in pastures and grassy woodlands, on roadsides, and along creeks and rivers, it is increasingly invading native grasslands. It tolerates drought and heavy grazing, and is able to establish on even the hardest bare sites on disturbed ground.
Flower colour:
Green, Purple
Distribution map:
Impacts:
Chilean Needle Grass (Nassella neesiana) is a Weed of National Significance. It is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. It is closely related to another Weed of National Significance, Serrated Tussock (Nassella trichotoma).
Chilean Needle Grass affects both sown pasture and native grasslands of south-eastern Australia. It is relatively unpalatable and reduces farm productivity by displacing more desirable pasture species. Heavy infestations can decrease productivity by as much as 50% during summer. It can completely overrun pastures resulting in a canopy cover of up to 60%, which leads to a substantial reduction of stock carrying capacity during late spring and summer when the weed produces large quantities of unpalatable flower which have been found have been found to move through the skin and into the body muscles of cattle, causing abscesses and downgrading carcasses, and even rendering them unsalable. These impacts can significantly affect the value of agricultural products.
The seeds of Chilean Needle Grass are also known to cause discomfort to dogs and humans, thereby restricting human access in recreational and other areas. A survey estimated the average annual cost of controlling Chilean Needle Grass at $60-120 per ha, depending on whether the infestation was scattered or dense.
Chilean Needle Grass is possibly the worst environmental weed threatening endangered indigenous grasslands in south-eastern Australia.Chilean Needle Grass is also invading grassy open woodlands and riparian vegetation in many areas. Degradation of native grassland and other habitats will have impacts on native birds and other fauna.
Origin:
Chilean Needle Grass is native to South America, including Ecuador, Bolivia, Chile, Argentina, Uruguay and southern Brazil. There are about 80 species of Nassella from the Americas. None of the seven Nassella species occurring in Australia are native.
