|
Lobed needle grass: State prohibited weed | LC0264 |
Department of Primary Industries, Frankston
April 2004 |  |
To view the Adobe Acrobat file, you will need the Adobe Acrobat reader. |  (PDF 256 kb) | |
This Landcare Note describes the weed lobed needle grass, Nassella charruana.
Common name
Lobed needle grass
Botanical name
Nassella charruana (Arechav.) Barkworth
Synonym Stipa charruana Arechav. Family Poaceae.
Status
Lobed needle grass is closely related to serrated tussock, one of Victoria’s worst weeds, and has the potential to cause major economic and environmental damage.
Lobed needle grass can easily be overlooked because of its similarity to indigenous tussock grasses and other Nassella species. The known distribution is currently limited to a number of small infestations and one large infestation (>20 ha) on the northern outskirts of Melbourne, where management programs aim to eradicate it. The potential distribution of lobed needle grass in Australia has been estimated to be 600,000 ha, with a substantial area of Victoria at risk.
Figure 1. Lobed needle grass.
Origin and distribution
Indigenous to Uruguay, Argentina and southeast Brazil and naturalised in Australia only in Victoria, in the outer northern Melbourne suburbs. Believed to have been present for more than 40 years near Cooper Street in Epping. In Victoria it occurs primarily in open areas on clay soils (the preferred soil type in South America) and appears to prefer wet depressions, but also occurs on stony rises.
Figure 2. Lobed needle grass infestation.
Description
A perennial tussock-forming grass in the spear grass group (Tribe Stipeae) growing to 25-80 cm high with a very distinctive seed with large apical lemma lobes (Figure 4).
Stems – flowering stems unbranched, up to 1 m high.
Leaves – basal, 20-50 cm long, 0.7-1 mm wide, rolled inwards, not sharp, not hairy: with a short, membranous ligule (the smallest basal appendage which sheaths the stem on the inner side of the leaf) (Figure 5).
Flowers – occurring on a 10-20 cm length of the upper end of the flowering stem: shiny, not purplish; each floret enclosed by two 14-20 mm long, yellowish white, pointed, 3-5 veined, papery bracts, the lower bract longer than the upper; the floret consisting of a lemma and palea (forming the husk of the seed) and an awn (the long bristle-like appendage extending from the end of the seed): the lemma at least 4 mm long, 0.6-0.9 mm wide, straw coloured.
Seeds –with a 5-8 mm long collar (corona) of firm, paper-like, whitish tissue extending from the head of the lemma and enclosing the base of the awn; the corona about as long as, or longer than, the main body of the seed, with a firm basal section about 3 mm long, and divided at its end into 0.5-1.9 mm long ‘fingers’, in turn divided into fine 0.5 mm long hairs. Ripe lemma is chestnut brown, tough and stiff, and usually hard and roughened. Awn 60-85 mm long, twice bent, not readily detached from the seed and with basal twisted section 12-20 mm long (figures 4 & 6).
Roots - fibrous.
Figure 3. Seed heads of lobed needle grass.
Figure 4. Seed of lobed needle grass showing the large whitish lobes of the corona (arrowed).
Figure 5. Stem and leaf base with the ligule (arrowed).
Similar species
Four other species of Nassella are naturalised in Victoria:
- N. trichotoma (Nees) Hack. ex Archav., serrated tussock
- N. neesiana (Trin. & Rupr.) Bark., Chilean needle grass
- N. hyalina (Nees) Barkworth, cane needle grass
- N. leucotricha (Trin. & Rupr.) Pohl, Texas needle grass.
They can be distinguished from lobed needle grass as follows: serrated tussock seeds lack a corona; the corona of Texas needle grass is less than 3 mm long and that of Chilean needle grass is less than 1.5 mm long; the awn of cane needle grass is 40 mm long or less. The distinctive long, whitish, lobed corona of cane needle grass is the best identifying character.
Figure 6. Seeds (bracts removed) of Mexican feather grass (N. tenuissima), serrated tussock (N. trichotoma), Chilean needle grass (N. neesiana) and lobed needle grass (N. charruana).
Properties
Lobed needle grass forms dense competitive infestations. In Victoria it has invaded open woodlands and native and introduced grasslands including grassland dominated by other Nassella species. In Argentina, N. charruana is considered very poor fodder and, unlike serrated tussock and Chilean needle grass, an extremely damaging weed due to its invasiveness, competitiveness, unpalatability and very sharp, clinging seeds that penetrate the fur and skin of livestock.
Management
The Department of Primary Industries (DPI) is responsible for the control of State Prohibited Weeds.
A small population at Janefield Reserve was sprayed by Parks Victoria in 1997 and 1998 and appears to have been eradicated. DPI commenced a program to eradicate this weed in Epping in 1998. The infestation, occurring directly in line with planned road works, was sprayed prior to the works commencing and contaminated soil was stockpiled at a special site to enable control of regrowth. The road contractor planned a vehicle hygiene program to reduce spread of the weed. Small infestations in Melbourne’s northern suburbs are being targeted for eradication whilst efforts continue to contain the large infestation at Epping.
Suspect plants should immediately be reported to the nearest DPI office. Manual and chemical control measures are used on infestations. Flowering specimens can be collected and sent to the National Herbarium of Victoria, Birdwood Avenue, South Yarra, 3141, to confirm their identification. DPI can determine how best to eradicate new infestations.
References
- Keith Turnbull Research Institute (1999) Chilean needle grass identification. Landcare Notes LC0256, Department of Natural Resources and Environment.
- Department of Primary Industries, (2004) Mexican Feathergrass: State Prohibited Weed. Landcare Notes LC0263,
- McLaren, D.A., Stasjic, V. and Gardener, M. (1998) The distribution and impact of south/north American stipoid grasses (Poaceae: Stipeae) in Australia. Plant Protection Quarterly 13(2), 62-70.
- Shepherd, R.C.H. and Richardson, R.G. (Eds.) (1998) Proceedings of the Nassella Workshop. Plant Protection Quarterly 13(2), 59-103.
- Walsh, N. (1998) Identification of South American tussock weeds. Plant Protection Quarterly 13(2), 59-62.
Acknowledgements
Compiled by Ian Faithfull and updated by Penny Gillespie and Ian Faithfull. David McLaren provided information, comment and figures 1, 3, 4 & 5. Figure 2 by Daniel Joubert. Seed drawings by Enid Mayfield.
This publication may be of assistance to you but the State of Victoria and its officers do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
|
