Description
Lobed Needle Grass (Nassella charruana) is a perennial, tussock-forming spear grass growing to about 1 m high. The leaves are narrow and rolled inwards (to 50 cm long and 2 mm wide) and, like other tussock grasses, grow from the plant base. The leaves have a short (to 1 mm long) membranous ligule, which is a small flap at the junction of the leaf blade and the leaf sheath. The ligule can be located by tracing a leaf down to where it joins the sheath and bending the leaf back at this point.
The shiny branching flower heads (called panicles) grow to 30 cm long. There is a single flower in each spikelet composed of a floret enclosed by two 14-20 mm long, yellowish white or strawcoloured, pointed bracts called glumes. At the top of the dark brown lemma (which becomes the husk of the seed) are 2 distinctive pale brown to white lobes (from which this grass gets its name). The body of the seed is 4-10 mm long and less than 1 mm wide with a corona, a whitish, papery collar up to 10 mm long at the seed base. The bristle-like tip of the seed (called an awn) is up to 8.5 cm long, twisted in the basal section and twice bent.
For further information and assistance with identification of Lobed Needle Grass contact the herbarium in your state or territory.
Distribution:
Lobed Needle Grass’s known distribution in Australia is limited to a few small infestations on the northern outskirts of Melbourne: from Thomastown, Plenty Gorge Metropolitan Park and near Cooper Street in Epping, where it is thought to have been present for more than 40 years.
Habit:
Grass
Key points:
- Lobed Needle Grass (Nassella charruana) is an invasive, unpalatable tussock grass to 1 m high.
- Dense infestations exclude other more desirable species.
- It has very sharp seeds which are easily spread by attaching to clothing, fur or machinery.
- It is distinguished by having two distinctive pale brown to white lobes at the top of the dark brown lemma enclosing the seed.
- In Australia it is limited to a few small infestations on the northern outskirts of Melbourne but it may easily spread without continued vigilance.
How it spreads:
Lobed Needle Grass reproduces by seed. Although the exact amount of seed produced is not known, the closely related species serrated tussock (Nassella trichotoma) and Chilean needle grass (N. neesiana) can produce tens of thousands of seeds per plant per year. The seeds are very sharp, and readily attach themselves to clothing, fur and equipment. Seeds can also be spread when soil is moved. Major roadworks near the site of one infestation led to the spread of Lobed Needle Grass. Anecdotal evidence suggests that the seedheads are not carried by wind like serrated tussock.
Based on climate suitability, the potential distribution of Lobed Needle Grass in Australia has been estimated at 600 000 ha. It could expand its range in Victoria and spread into eastern New South Wales, the Australian Capital Territory, south-eastern South Australia, north-eastern Tasmania and possibly south-eastern Queensland and south-western Western Australia.
Where it grows:
Stipoid grasses (such as the Nassella species) generally invade sites that are already highly degraded, especially land with higher fertility soil that has been used for grazing or farming. As well as growing in urban areas and on rural roadsides, Lobed Needle Grass has invaded open woodlands and native and introduced grasslands including grassland dominated by four other Nassella species.
It grows mainly in open areas, in direct sunlight or light shade, on clay soils - its preferred soil type in South America. It is tolerant to waterlogging and appears to prefer wet depressions, but it also occurs on stony rises.
Flower colour:
White
Distribution map:
Impacts:
Lobed Needle Grass is on the Alert List for Environmental Weeds, a list of 28 non-native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, Lobed Needle Grass has the potential to seriously degrade Australia’s ecosystems.
Lobed Needle Grass is closely related to Serrated Tussock (Nassella trichotoma), a Weed of National Significance that costs south-eastern Australia’s grazing industries more than $40 million a year in control expenditure and lost production.
Even in its native Argentina, where the relatively unpalatable serrated tussock (Nassella trichotoma) and Chilean Needle Grass (N. neesiana) are used as fodder, Lobed Needle Grass is regarded as a serious weed due to its invasiveness and competitiveness and lack of usefulness as fodder. It is drought tolerant and forms dense infestations. While cattle may be able to tolerate Lobed Needle Grass, it is a major problem for sheep because the sharp seeds can damage skins and carcasses and contaminate fleeces. As seen with the closely related Serrated Tussock and Chilean Needle Grass, infestations of Lobed Needle Grass would result in significant loss in livestock production.
Lobed Needle Grass is a successful competitor with native grasses and is impacting on native grasslands and open woodlands.
Origin:
Lobed Needle Grass is native to Uruguay, Argentina, Paraguay and south-eastern Brazil.
