Title: Pennisetum macrourum Trin.

Scientific Name:

Pennisetum macrourum Trin.

Common Name:

African feather grass



Source & more images (via ALA)

Habitat: Subhumid warm-temperate regions where it occurs normally on streambanks, roadsides and poorer pastures, often in areas of sandy soil and annual rainfall above 600 mm. (Parsons and Cuthbertson 1992). African feather grass invades lowland grassland & grassy woodland, riparian vegetation, and freshwater wetlands (Carr et al. 1992).

Distribution:



Original source via CABI


Invasiveness Assessment

ESTABLISHMENT


1. Germination requirements? “Most reproduction is by rhizomes which grow rapidly in spring and summer.” Requires natural seasonal disturbance such as spring/summer temperatures. (Parsons and Cuthbertson, 2001)

2. Establishment requirements? “…it occurs normally on streambanks, roadsides and poorer pastures.” “Plants dislike shading and rarely establish under forest canopies.”
Carr et al (1992) states the grass mostly occurs in lowland grassland & grassy woodland, riparian vegetation and freshwater wetland (seasonal). Requires open space for optimal growth. (Parsons and Cuthbertson, 2001; Carr et al., 1992)

3. How much disturbance is required? While it occurs on roadsides and waste place, it is also present on the banks of small creeks and rivers, and poorly maintained pastures. Establishes in areas that are subject to some disturbance (DPIWE, 2002).

GROWTH / COMPETITIVE


4. Life form? Perennial grass. “The plants become dormant more or less dormant through winter new shoots being produced from rhizomes and crowns each spring.” (Parsons and Cuthbertson, 2001)

5. Allelopathic properties? None reported.

6. Tolerates herb pressure? "The coarse leaves of mature plants are of low palatability and not grazed by stock except when there is an extreme shortage of other feed, such as in times of drought.” Consumed but not preferred by grazing animals. (Parsons and Cuthbertson, 2001)

7. Normal growth rate? “Many infestations are small and do not spread readily but, under suitable conditions, strong rhizome growth produces dense clumps within a few years.” Moderately rapid growth rate under optimum conditions. (Parsons and Cuthbertson, 2001)

8. Stress tolerance to frost, drought, w/logg, sal. etc? “Established plants are relatively drought resistant.” “Large plants are also capable of totally blocking waterways and channels by trapping silt and debris.” Able to withstand waterlogging. (Parsons and Cuthbertson, 2001; DPIWE, 2002)

REPRODUCTION


9. Reproductive system? Reproduces by seed and rhizomes. (Parsons and Cuthbertson, 2001)

10. Number of propagules produced? “In dense patches, over 100,000 seeds have been produced per square metre per year, but in most years the number is far less because usually many florets are sterile.” Each plant may produce more than 2,000 seeds per annum. (Parsons and Cuthbertson, 2001)

11. Propagule longevity? “The majority of seeds are not long lived in the soil but a small proportion appears to remain viable for several years under field conditions.” “The seeds exhibit a high level of viability, however, dormant longevity is restricted to a few years.” Seeds survive < 5 years. (Parsons and Cuthbertson, 2001; DPIWE, 2002)

12. Reproductive period? The plant reproduces mostly by vegetative means from stout rhizomes. Shoots are produced from rhizomes and crowns each spring. While it dominates the vegetation in discrete patches, it is not known to create monoculture.

13. Time to reproductive maturity? Start producing seeds after 2 to 3 years in reasonably good conditions (Beckmann, 1990).

DISPERSAL


14. Number of mechanisms? Light seeds well adapted to wind dispersal (ARMCANZ, 2000). Dispersed by water (especially floodwaters). May be dispersed by animals and birds (Parsons & Cuthbertson, 2001).

15. How far do they disperse? Thought to spread long distances in floodwaters and as also spread by birds (Parsons & Cuthbertson, 2001) it is very likely that some propagules will disperse greater than 1 km.


Impact Assessment

RECREATION


1. Restrict human access? “Perennial grass generally 1 to 1.8 m high.” “…dense growth…prevents access to streams.” (Parsons and Cuthbertson, 2001)

2. Reduce tourism? “Perennial grass generally 1 to 1.8 m high.” “…dense growth…prevents access to streams.” (Blood, 2001)

3. Injurious to people? No recorded toxic properties.

4. Damage to cultural sites? Noticeable presence of infestation, but as a shade intolerant grass it is unlikely to affect cultural structures or features. (Blood, 2001)

ABIOTIC


5. Impact flow? In Tasmania, “Large plants are also capable of totally blocking waterways and channels by trapping silt and debris.” (DPIWE (Tas.), 2002 - Agdex 647 106/98)

6. Impact water quality? No known effect on water quality. However, with the potential to block waterways and channels, P. macrourum would negatively affect water quality. (DPIWE (Tas.), 2002 - Agdex 647 106/98)

7. Increase soil erosion? “Perennial grass with fibrous roots extensive, to depth of 1 m. Stout rhizomes to 2 m long.” Unlikely to cause soil erosion. (Blood, 2001)

8. Reduce biomass? “Weed of lowland grassland and grassy woodland.” Potential to suppress overstorey regeneration in grassy woodland areas. Biomass would likely decrease slightly. (Blood, 2001; Carr et al., 1992)

9. Change fire regime? “Dense infestations are a fire hazard.” (DNRE, 1998 - Landcare Note 0197)

COMMUNITY HABITAT


10(a) Impact on composition of high value EVC? EVC=Plains grassy woodland (E); CMA=Glenelg Hopkins; Bioreg=Goldfields; VH CLIMATE potential Invades lowland grassland & grassy woodland, riparian vegetation and seasonal freshwater wetland. When occurring in, “…dense clumps…[it] virtually eliminates all other plants. Plants dislike shading and rarely establish under forest canopies.” Major displacement of grass species. (Parsons and Cuthbertson, 2001)

10(b) Impact on medium value EVC? EVC=Sedge-rich wetlands (D); CMA=Glenelg Hopkins; Bioreg=Greater Grampians; VH CLIMATE potential. It is recorded in Carr, et al. (1992) as occurring in freshwater wetland (seasonal) and it usually occurs in medium to large populations. Assume major displacement of grasses/forbs. (Carr et al., 1992)

10(c) Impact on low value EVC? Not a significant weed in low value EVCs. Mostly occurs in endangered grassland situations.

11. Impact on structure? When occurring in, “…dense clumps…[it] virtually eliminates all other plants.” Occurs in open grasslands; affects grass and forbs. (Parsons and Cuthbertson, 2001).

12. Effect on threatened flora?

FAUNA


13. Effect on threatened fauna?

14. Effect on non-threatened fauna? “…under suitable conditions strong growth produces dense clumps within a few years.” Low palatability may result in reduced food source for non-threatened fauna. (Parsons and Cuthbertson, 2001)

15. Benefits fauna? See comment in Q16 above. Provides little support. “…leaves have low palatability (for stock).” (Parsons and Cuthbertson, 2001)

16. Injurious to fauna? No known toxic or hazardous effects

PEST ANIMAL


17. Food source to pests? Not known as a food source for pest animals.

18. Provides harbor? “dense growth provides harbor for rabbits.” (Parsons and Cuthbertson, 2001)

AGRICULTURE


19. Impact yield? “once established, improving the pasture alone does not control (the weed).” “under suitable conditions,…dense clumps virtually eliminate all other plants.” Has affected softwood industry in Casterton, Victoria. (Parsons and Cuthbertson, 2001; John Matthews, Catchment Management Officer, DPI Casterton, 11/03/03. Pers. Com.)


20. Impact quality? “Because of their bristles, seeds are equipped to cling to the wool and hair of animals.” Potential to reduce the quality of wool. (Parsons and Cuthbertson, 2001)

21. Affect land values? With the potential to dominate in pasture grasses, grazing land could be seriously affected by price reduction due to low palatability of plant. (Parsons and Cuthbertson, 2001)

22. Change land use? Infested areas unusable for grazing purposes without significant control activities. “…once the weed is established, improving the pasture alone does not control it.” Where dense infestations occur in pastures, the land use would need to be changed. e.g. agroforestry. “Requires full sun: rarely will a dense infestation occur within a shady bushland environment.” (Parsons and Cuthbertson, 2001; DPIWE (Tas.), 2002 - Agdex 647 106/98)

23. Increase harvest costs? No known effect on harvesting costs. It is predominantly a weed of pasture, not cropping. (Cultivation is effective in controlling the plant.) (Parsons and Cuthbertson, 2001)

24. Disease host/vector? None evident




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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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Date: 29 September 2009; 12:40:05 PM AEST

Author Name: David Low
Author ID: adminDavid