Title: Nassella leucotricha (Trin. & Rupr.) R.W. Pohl

Scientific Name:

Nassella leucotricha (Trin. & Rupr.) R.W. Pohl

Common Name:

Texas needle grass




Source & more images (via ALA)

Habitat: Grows best on deep loam soils (Leithead et al. ,1971). It is a weed of disturbed areas, especially roadsides, heavily grazed pastures and dry open grasslands (Gould, 1975; Hitchcock, 1950). Stipoid grasses generally invade plant communities that are already highly degraded and have a history of disturbance, and lands previously used for grazing and farming (Gardener, & Sindel, 1998). It is not highly shade tolerant and is replaced in woodland areas (Gould, 1975). Potential distribution produced from CLIMATE modelling and overlayed on suitable overlays with CMA boundaries.



Distribution:



Original source via GBIF


Invasiveness Assessment

ESTABLISHMENT


1. Germination requirements? Growth is seasonal, so germination also assumed seasonal (Leithead, 1971).

2. Establishment requirements? Similar to N. Neesiana which establishes well in moderate shaded habitats (Gould, 1975).

3. How much disturbance is required? “Thrives under conditions of moderate disturbance and is frequently abundant on roadsides and heavily grazed pastures”. Also a serious weed of grassland communities. (Gould, 1975; McLaren et al., 1998).

GROWTH / COMPETITIVE


4. Life form? Grass-belonging to the family Poaceae (TROPICOS, 2000).

5. Allelopathic properties? None described.

6. Tolerates herb pressure? Grazed by all livestock – consumed but recovers quickly/slowly? Produces seeds under moderate herbivory (Leithead et al, 1971).

7. Normal growth rate? “Makes most rapid growth in early fall before cold weather” (Leithead et al, 1971).

8. Stress tolerance to frost, drought, w/logg, sal. etc? Tolerant of drought (occurs in dry areas of Oklahoma, Texas and Central Mexico) (Hitchcock, 1950).

REPRODUCTION


9. Reproductive system? Plants bisexual with bisexual spikelets: with hermaphrodite florets. The spikelets all alike in sexuality (Watson & Dallwitz, 1985).

10. Number of propagules produced?


11. Propagule longevity?


12. Reproductive period? Short-lived perennial sp. – because short-lived, probably a short reproductive period.

13. Time to reproductive maturity? Short-lived perennial sp. – because short-lived, probably a short time to reproductive maturity – assumed < two years.

DISPERSAL


14. Number of mechanisms? “Seeds become attached to the hair and wool of grazing animals, which help distribute them” (Leithead, 1971).

15. How far do they disperse? Animals could disperse 200-1000 m from source.


Impact Assessment

RECREATION


1. Restrict human access? Tufted perennial grass to 1 m high (Walsh & Entwistle, 1994). Would not restrict human access.


2. Reduce tourism? As with the other Nassella spp. Texas needle grass looks very similar to native Austrostipa spp (Walsh, 1998). It is thus unlikely that the average visitor would notice this grass as being a weed.

3. Injurious to people? As a generalisation, it is considered that the sharp seeds of Nassella spp. penetrate and damage sheep skins and carcases. ("To prevent seed from injuring sheep…remove sheep for 2 to 3 weeks until seed ripen and fall to the ground." (Leithead et al, 1971)) However, such potential to injure humans very limited. Little to no effect.

4. Damage to cultural sites? "In Victoria, N. leuchotricha, invades mostly in native pasture and native grasslands." (McLaren et al, 1998). When present with other grasses it is probably not readily noticeable. No visual or structural impact.

ABIOTIC


5. Impact flow? Terrestrial sp.

6. Impact water quality? Terrestrial sp.

7. Increase soil erosion? In its native range, Texas needle grass is a short-lived perennial. "Because its foliage disintegrates rapidly at end of growing season, it is a poor grass for soil protection." (Leithead et al., 1971). Bare patches of soil may be left exposed to wind erosion. Moderate probability of large-scale soil movement.

8. Reduce biomass? Having a short growing season, where it replaces native grasses Texas needle grass may create a slight reduction in biomass (Leithead et al., 1971).

9. Change fire regime? Foliage disintegrates rapidly at the end of the growing season (Leithead et al, 1971). Little addition to fuel load; no change to fire regime.

COMMUNITY HABITAT


10(a) Impact on composition of high value EVC? EVC=Grassy Woodland (E); CMA=Corangamite; Bioreg=Victorian Volcanic Plain; VH CLIMATE potential. "Stipoid grasses generally invade plant communities which are already highly degraded,…and evidence suggests that there is a drop in biodiversity in stipoid grass-dominated grasslands." (Gardener & Sindel, 1998). Minor displacement of some dominant spp.

10(b) Impact on medium value EVC? It appears unlikely to occur or have any significant impact in medium value EVCs across the southern areas of Victoria. (Refer to potential distribution map.)

10(c) Impact on low value EVC? It appears unlikely to occur or have any significant impact in low value EVCs across the southern areas of Victoria. (Refer to potential distribution map.)

11. Impact on structure? Where it occurs in Victoria, it forms part of a mixed vegetation community. However, its presence will displace other more desirable native grass species (McLaren et al, 1998). Likely to have at least a minor impact on the lower stratum.

12. Effect on threatened flora? This species is not documented as posing an additional risk to threatened flora.

FAUNA


13. Effect on threatened fauna? This species is not documented as posing an additional risk to threatened fauna

14. Effect on non-threatened fauna? In Texas, it provides good forage as it is one of the few green grasses during winter (Leithead et al., 1971). While it may displace some native grasses, it might also provide suitable alternative fodder to native herbivores.

15. Benefits fauna? No known benefits. It may provide additional food source during winter. See comment in 14 above. May provide some assistance.

16. Injurious to fauna? The sharp seeds of Nassella spp. are considered to damage the skin and carcases of sheep, however, it is not known if fauna is subjected to similar threat.

PEST ANIMAL


17. Food source to pests? Not documented as a food source to pest animals. A grass with that is, "…green and succulent," during winter (Leithead et al., 1971), it may provide an alternate food source during that time.

18. Provides harbor? Short-lived perennial bunch grass. Foliage dies back rapidly after growing period (Leithead et al., 1971). Unlikely to provide harbour to pest animals.

AGRICULTURE


19. Impact yield? Not known to occur in managed pasture; "In Victoria, N. leucotricha, invades mostly in native pasture and native grasslands." (McLaren et al., 1998). More commonly occurs as an environmental weed. In pasture situations it may be useful as fodder during winter. Not likely to affect yield in managed pastures.

20. Impact quality? See comments in 19, above. Where sheep graze, Texas needle grass has the potential to damage sheepskins and carcases, and is a likely contaminant of wool. Minor impact.

21. Affect land values? Not known as a weed of agriculture. No effect on land value.

22. Change land use? See comments in 19, 20 and 21 above.

23. Increase harvest costs? Not known in cropping situations. A perennial grass. Does not affect harvesting costs.

24. Disease host/vector? Along with other Nassella spp., Texas needle grass is not documented as a host or vector of disease.




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Assessment ratings originally made by the Victorian Department of Primary Industries.
The entry of this assessment was made possible through the generous support of The Weed's Network.






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wra4478: re: Nassella leucotricha (Trin. & Rupr.) R.W. Pohl
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wra1036: Common Name - T (via Texas needle grass)
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Date: 9 November 2009; 1:08:04 PM AEDT

Author Name: Jessica Mackay
Author ID: mackayj