Texas Needle-Grass

Note number: LC0265
Published: February 2000

This Landcare Note describes the weed Texas needlegrass, Nassella leucotricha.

Common name

Texas needle-grass

Botanical name

Nassella leucotricha (Trin. & Rupr.) Pohl.

Synonym Stipa leucotricha Trin. & Rupr. Family Poaceae

Status

Figure 1. Texas needle-grass.

Texas 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. Texas needle-grass can easily be overlooked because of its similarity to indigenous tussock grasses and other Nassella species such as Chilean needle-grass (Nassella neesiana) and lobed needle-grass (Nassella charruana).

The known distribution is currently limited to a few small infestations around Victoria, where management programs aim to eradicate it. However the potential distribution of Texas needle-grass in Australia has been estimated to be 4.8 million hectares, with a substantial area of Victoria at risk.

Origin and distribution

Texas needle-grass is indigenous to Oklahoma, Texas and Central Mexico and has naturalised in Australia only in Victoria. The weed was first discovered in 1934 in Northcote, Melbourne. It has since spread and infestations have been recorded at Taradale, near Castlemaine, Mt Beckworth near Ballarat, and several infestations around Geelong and Melbourne, mostly on basaltic soils. Theseinfestations occur almost exclusively on roadsides.

Figure 2. Texas needle-grass infestation.

Descriptions

Texas needle-grass is a perennial tussock-forming grass in the speargrass group (Tribe Stipeae). It grows to about 1 – 1.5 m high. The weed thrives under conditions of moderate soil disturbance and poses a threat to agriculture and native vegetation. Flowering time is from October to February.

In South America, the plant is known to produce stem seeds (cleistogenes), concealed under leaf sheaths at the base of the plant that enable it to reproduce even when flowering is prevented by grazing or slashing. As yet, these have not been recorded in Australia.

Stems – Erect, unbranched, to 1 or 1.5 m, mostly hairless.

Leaves – approximately 30 cm long and 5 mm wide. The blades appear flat or slightly inrolled. The ligule (the smallmembranous appendage on the inner side of the leaf where it sheaths the stem) is 0.5-1 mm long and hairless.

Figure 3. Flowering head (panicle) of Texas needle-grass.

Flowers – borne in a contracted panicle to 25 cm long.

Seeds – Vary from a pale brown to purple in colour at maturity. Glumes (the outermost and lowest bracts) measure 11- 15 mm long, lemma (the lower of the two bracts around the seed) 6-9 mm, palea (the innermost bract bract around the seed) 1-2 mm and callus (the hardened extension at the base of the seed) 1-3 mm. The corona (the hardened ring of tissue at the apex of the lemma) is 1mm long with erect apical hairs (or slender spines), extending from it. These hairs are 0.6-1.5 mm long. The awn (the fine, bristle-like appendage extending from the lemma) is bent twice and is 35-60 mm long, with 10-20 mm to the first bend.

Figure 4. Texas needle-grass seeds

Roots - fibrous.

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. charruana (Arech.) Barkworth, lobed needle-grass

They can be distinguished from Texas needle-grass as follows. Serrated tussock seeds lack a corona. The seed of Chilean needle-grass is larger than that of the Texas needle-grass - the length of the awn is almost double, 60- 90 mm compared to 35-60 mm. The lemma of cane needle-grass measures 3.5-6 mm, usually much smaller than that of Texas needle-grass, which measures over 6 mm. Lobed needle-grass has distinct large whitish lobes on its corona.

Properties

Texas needle-grass is highly invasive and can form dense infestations, particularly on poorly managed sites. It prefers open grassland sites similar to those favoured by native grassland species.

Due to its invasive growth, vigorous reproduction, and potential for long distance dispersal, Texas needle-grass has the potential to further spread from these known sites.

The species is known as Texas wintergrass in its native Texas where it is regarded as a plant of significant fodder value and is readily grazed by stock in winter and early spring. There has been no research conducted on its nutritional value in Australia, however it is definitely an undesirable species for Victorian grazing lands.

The sharp, pointed seeds have been known to be carried long distances by attaching themselves to the wool or fur of animals. These sharp intrusive seeds can be a hazard to animals and contaminate produce.

Management

Read about management and control of invasive plants

References

Keith Turnbull Research Institute (1999) Chilean needle grass identification. Landcare Notes LC0256, Department of Natural Resources and Environment.

Keith Turnbull Research Institute (1999) Mexican feather grass. Landcare Notes LC0263, Department of Natural Resources and Environment.

Keith Turnbull Research Institute (1999) Lobed needle grass. Landcare Notes LC0264, Department of Natural Resources and Environment.

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. (1994) Poaceae. Pp. 356-627 in Walsh, N.G. and Entwisle, T.J. (Eds.) Flora of Victoria Volume 2. Ferns and Allied Plants, Conifers and Monocotyledons. Melbourne, Inkata Press.

Walsh, N. (1998) Identification of South American tussock weeds. Plant Protection Quarterly 13(2), 59-62.

Acknowledgements

This Information Note was originally developed by Linda Penhall and Rick James, (Ballarat), and Ian Faithfull, (Frankston)

This Information Note was  developed by David McLaren provided information and comment. Photographs by Linda Penhall.