Quick Facts

Quick facts

• Originally from southern USA and Mexico, Texas Needle Grass (Nassella leucotricha) is a tough perennial tufted upright grass to about 1 to 1.5 meters tall, leaves are about 30 cm long and 5 mm broad, with abundant seed production on flower spikes in summer, but it is difficult to identify without seeds.
• It poses a threat in cool to warm temperate, to sub-tropical areas, preferring areas with rainfall over 500 mm, growing in rich to poor degraded soils, readily invading pastures and native grasslands excluding desirable species.
• Producing abundant flowering seeds, and also produces hidden stem seeds, found at the base of the plant, and in the joints (nodes) of the stem which means the plant can reproduce even when the main seed head is destroyed.
• The current distribution of Texas Needle Grass in Australia is relatively small but has the potential to affect 4.8 million hectares across Australia.
• Reduces nutritional value relative to improved pastures, and if animals are present in summer when the sharp flowering seeds are produced, these can injure and damage animals, downgrading produce.
• Rehabilitation of infested land is very difficult, for best results, combine herbicide application with physical removal, crop rotation, pasture sowing and  high intensity grazing management for a short duration.
• All control programs should aim to reduce the amount of seed produced, with prevention and early detection the most cost-effective form of weed control, with quarantine and good hygiene within infestations preventing spread.

What Does It Look Like?

What is it?

Texas Needle Grass (Nassella leucotricha) is a perennial (long-lived) tussock forming grass to about 1 to 1.5 meters tall with upright leaf stems with slender flowering stems with a fibrous root system. Stems are erect producing leaves at nodes (joints on the stems where leaves or branches arise). Leaves are about 30 cm long and 5 mm broad, glabrous (without hairs, scales or bristles) or sometimes sparsely pubescent (downy; covered with short, soft, erect hairs) with a flat blade sometimes somewhat in-rolled, with a leaf-sheath rolled around the stem where the blade meets the stem. The ligule is a membranous small flap  0.5–1 mm long at the junction of the leaf blade and the leaf sheath meet on the stem. The ligule can be located by tracing a leaf down to where it joins the sheath and bending the leaf back at this point. Most leaves are clumped around the base and are capable of producing cleistogenes, sometimes referred to as stem seeds, (modified spikelet produced within the lower leaf-sheaths), which enable the plant to produce seed even if the main seed head is destroyed.

The Inflorescence seed/flower head is a contracted panicle to 25 cm long. Many spikelets (flowers) are contained within flower head. Glumes (pointed bracts) 11–15 mm long,  hyaline (translucent, usually delicately membranous and colourless) to straw-coloured, with pointed tips, equal in length or sub-equal. Contained within the glumes is a lemma which becomes the husk of the seed,  

The pointed sharp seeds are pale brown to purple with a long awn (bristle-like appendage). A distinct feature is the collar-like structure, called a corona 1 to mm (excluding the erect apical hairs or slender spines 0.6–1.5 mm long) present where the awn attaches to the seed. The lemma (seed) is  6–9 mm long, pale brown or purplish at maturity, partially smooth glabrous with some small like wart-like growths, and except near callus and along midrib. The callus (the point of the seed) is 1–3 mm long. The awn is twice bent, 35–60 mm long, 10–20 mm to the first bend,  (Penhall et al. 2000; Muyt 2001; Navie 2004; VicFlora 2021).

For further information and assistance with identification of Texas Needle Grass contact the herbarium in your state or territory.

Flower colour

Green

Growth form (weed type/habit)

Grass

Where it currently grows? Preferred habitat

Texas Needle Grass prefers open and sunny conditions similar to that preferred by many native grass species. Large infestations generally form in areas of low intensity management and poor agricultural land (Penhall et al. 2000). Unlike most other Nassella species, N. leucotricha is able to thrive in warmer, drier climates, due to its high water-use efficiency. This attribute was clearly important for its original development, being indigenous to Texas, Oklahoma, and central Mexico

Are there similar species?

Like many Nasella species, Texas Needle Grass can be easily confused with native Speargrasses (Austrostipa spp.) and other native tussock grasses (Poa spp.). There is a risk that control methods may be applied to the wrong species. Introduced Nassella species have a membranous ligule (a small flap at the junction of the leaf blade and leaf sheath) whereas native species either have no ligule or the ligule is fringed with hairs (Muyt 2001; McLaren et al. 1998; Navie 2004; Best 2008).

With the use of a microscope or hand lenses, Texas Needle Grass can be distinguished from some Nassella species by the existence of a corona, or collar, where the awn attaches to the seed. There are three other Nassella species, found in the same area as Texas Needle Grass, that also have a corona. These are Chilean Needle Grass (Nassella neesiana), Lobed Needle Grass (Nassella charruana) and Cane Needle Grass (Nassella hyalina or Nassella formicarum). Expert advice should be sought when trying to distinguish between these species as variation within each species may lead to incorrect identification (McLaren et al. 1998; Muyt 2001; Navie 2004).

Distinguishing between grass species can be extremely difficult. The use of field guides with line drawings and/or photographs is recommended as well as the use of hand lenses or microscopes. Any samples being sent away for expert analysis, e.g. to a state herbarium, ideally need to have complete seed heads containing seeds as well as leaves for correct identification.

Why Is It A Weed?

What are its impacts?

Texas Needle Grass forms dense infestations in pasture, native grasslands and woodlands where it can exclude desirable species. It has low feed value to stock, and is not palatable so tends to be allowed to increase as long as more palatable pasture species are present (Government of South Australia 2021), considered one of Australia’s worst weeds of native grasslands and pasture. If allowed to spread unchecked it is likely to have major environmental and economic costs (Government of South Australia 2019).

Agriculture: Reduces stock carrying capacity due to the production of masses of unpalatable flower stalks and provides very little leaf material during the warmer months and displaces desirable pasture species during spring and summer. Because the plant is avoided by grazing animals, infestations commonly expand as other species are selectively grazed out. Texas Needle Grass is considered a danger to livestock. The sharp, needle like points on the seeds can damage the eyes and face area and have been known to blind livestock. the sharp seeds penetrates wool, skin and underlying muscle of grazing animals resulting in injury, infection and the downgrading of wool, hides and carcasses (Government of South Australia 2019). Texas Needle Grass is considered a high value pasture crop as it remains green when other pasture is drying up. Stock are removed when the plants are in seed. In Australia the agricultural impact is considered negative due to the high invasive potential, loss of grazing land as well as the financial cost and time involved in removing this hardy weed species (Penhall et al. 2000; Magee 2005).

Native ecosystems: Biodiversity values are negatively affected by Texas Needle Grass through direct completion with native grassland species. It is considered one of the 49 non-native species that have a direct impact on Australian and New Zealand Environment and Conservation Council (ANZECC) rated rare or threatened plants within Victoria (Groves et al. 2003; Obst 2004). In native grasslands it displaces native forbs and grasses such as kangaroo grass and spear grass (Government of South Australia 2019).

How does it spread?

The aerial seeds of Texas Needle Grass easily attach to animals when it catches on the fleece of sheep or coats of livestock, or be picked up in mud on their hooves. It can also spread in produce such as fodder, grain, hay. People can spread it when the seeds attach to clothes, especially socks and pants. In South Australia infestations often occur on recreational land where there is a high rate of spread attributed to people and animal movement. 

Texas Needle Grass can be very effectively spread on farm machinery, clothing or livestock. It will attach to vehicles and machinery, for example, cultivation implements, vehicle tyres, slashing equipment, tractors, spray units, mowers and slashers, and bottom of vehicles, making it possible to spread over large distances. Seed has also been spread along roadsides and other grassy areas by mowing and earth-moving equipment. Stem seeds can be spread by most of these methods. It may also be transported by moving soil. Seed transported or buried in soil by cultivation can remain dormant for several years and produce seedlings after subsequent soil disturbance. Floodwater will move seed downstream (CRC 2003).

The other main dispersal method is seed transportation by water (Obst 2004; Best 2008).

What is its history in Australia?

The first known record of Texas Needle Grass in Australia was in the Melbourne suburb of Northcote in 1934. Texas Needle Grass is a listed as a seed sample in 1947 for the Commonwealth Plant Introduction program (Penhall et al. 2000; Cook & Dias 2006).

How To Manage It?

Best practice management

Control methods used for Texas Needle Grass are the same as for other Nassella species such as Chilean Needle Grass (Nassella neesiana) and Serrated Tussock (Nassella trichotoma). It is extremely vigorous and competitive. Land managers need to know how to identify it and take prompt action if it is discovered wit land managers mistaking plants for native spear grasses (Austrostipa species). Management options in established infestations will depend on land use and may include crop rotation, pasture sowing, herbicide control, cultivation, grazing, and other cultural management options. For best results a combination of options needs to be used (CRC 2003).

Non-chemical control: Physical control: The ideal removal method involves digging out the whole plan. Hand weeding or chipping is very effective on single plants or small patches, making sure to first cut and bag any flowering seeds or stem seeds. Plants cannot be left to dry in the paddock because of the basal and stem seeds. The whole plant needs to be destroyed.

Mowing and slashing may reduce seed set in the flower heads but it can actively disperse stem seeds if machinery is not kept clean. Mowing with a catcher mower during flowering will reduce seed set but it will not remove the basal and stem seeds. Clippings must be burnt and the mower must be thoroughly cleaned before it is used elsewhere (CRC 2003). Maintaining weed-free machinery and equipment is very important in preventing further spread of Texas Needle Grass. Check machinery moving onto your property and wash down vehicles and machinery in the same area to allow easy follow-up control of any seeds that may germinate. Don't buy hay, stock feed, or crop and pasture seed from infested areas. When controlling large infestations, mowing during the peak flowering period can be effective when followed up with additional mowing, timed to remove new flowers, as the plants will re-flower within two to six weeks. Mowing will not destroy infestations but can held reduce the spread of seed.

Competition and management: Control may be achieved using cultivation. Cultivation of the soil encourages seeds to germinate and these can be controlled. Sowing a dense pasture or crop will reduce the amount of Chilean Needle Grass that germinates. Rotational cropping and a mix of cultivation and herbicide application can be used to prevent seedling.

Grazing by animals at the correct time of year when no flowering seed-heads are present can be used. For larger areas larger mobs and a cycle of short duration of high intensity grazing followed by long rest periods offers the benefit of better pasture, fewer weeds and better livestock returns (CRC 2003).  However, Texas Needle Grass is of lower nutritional value than improved pastures and once it starts flowering the nutritional value decreases further. In addition, the sharp mature seeds attach to animals coats and can penetrate lips, skin and flesh causing harm to animals, downgrading and reducing the values of produce, be it wool or meat.

Mulching: Suitable for small infestations in native or urban areas, or larger infections in agricultural situations. Mulching is the the application of material over the ground such as straw, wood chips, carpet or plastic sheeting will prevent the growth of all plants, including weeds and beneficial plants. Organic mulch should be 100 mm thick, regularly topped-up as this reduces over time and used with other control methods to remove any unwanted plants that germinate.

Fire: The use of fire has a management tool has been used to burn-off and kill flowering and stem seeds in large infestations. Fire can be effective in areas with natives grassed and other Nassella species. A fire timed to encourage native grass growth can be used for competitive exclusion and targeted spot spraying (Muyt 2001). Other follow up controls methods are required to prevent regrowth and germination of seed

Chemical control: Herbicide treatment can be effective. Spot spraying is effective when used on individual plants and small infestations, and is used as a follow-up for other management practices to control cleistogenes (stem seeds) (Muyt 2001). For large infestations boom spraying as part of integrated weed management techniques can be useful. For up-to-date information on which herbicides are registered to control Chilean Needle Grass and the best application methods and dosages, contact your state or territory weed management agency or local council. 

Also see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au. Permits from state or territory Environment Protection Authorities may be required if herbicides are to be sprayed on riverbanks.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Texas Needle Grass is slow growing, but it has a high survival rate. It is a long lived perennial plant especially hardy to adverse weather conditions when mature. Flowering begins in early spring and the inflorescences take the form of a panicle, with these reaching up to 25 -30 cm in length, however, flowering and seeding can takes place at any time if favorable conditions allow (Best 2008).

Where Is It Found?

Which states and territories is it found?

SA, VIC

What areas within states and territories is it found?

Texas Needle Grass is found in Central Victoria especially north-western Melbourne as well as the Fleurieu Peninsular region of South Australia. While the infestations are relatively small compared to other weedy Needle Grass species, Texas Needle Grass has the potential to affect 4.8 million hectares across Australia (Penhall et al. 2000; Muyt 2001; Obst 2004).

Where does it originate?

Texas Needle Grass is native to the states of Texas and Oklahoma in the United States of America and Central Mexico (Penhall et al. 2000).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

SA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Nassella leucotricha

Other scientific names (synonyms)?

Stipa leucotricha Trin. & Rupr.

Does it have other known common name(s)?

Texas Needlegrass, Texas Wintergrass