Invasiveness Assessment - Feathertop (Pennisetum villosum) in Victoria

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Plant invasiveness is determined by evaluating a plant’s biological and ecological characteristics against criteria that encompass establishment requirements, growth rate and competitive ability, methods of reproduction, and dispersal mechanisms.

Each characteristic, or criterion, is assessed against a list of intensity ratings. Depending upon information found, a rating of Low, Medium Low, Medium High or High is assigned to that criterion. Where no data is available to answer a criterion, a rating of medium (M) is applied. A description of the invasiveness criteria and intensity ratings used in this process can be viewed here.

The following table provides information on the invasiveness of Feathertop (white foxtail).

A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:

Victorian Weed Risk Assessment (WRA) method (PDF - 630 KB)
Victorian Weed Risk Assessment (WRA) method (DOC - 1 MB)
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Common Name: Feathertop (white foxtail)
Scientific name: Pennisetum villosum

Question	Comments	Rating	Confidence
Establishment
Germination requirements?	Seeds germinate in early summer, however most reproduction is from the crowns and rhizomes during late spring and summer (Parsons & Cuthbertson 1992). Requires natural seasonal disturbances, e.g. warm temperatures, for germination.	MH	MH
Establishment requirements?	Habitat information suggests it occurs primarily in open areas, e.g. pasture, roadsides (Parsons & Cuthbertson 1992, Walsh & Entwisle 1994) and is documented to require a ‘full sun’ position (Dave's Garden 2008). Appears to need more specific requirements to establish, e.g. open space and access to light.	ML	MH
How much disturbance is required?	Appears to establish in areas that have a greater impact by humans, e.g. roadsides, urban & coastal areas, pasture (Parsons & Cuthbertson 1992, Harden 1993). ‘Neglected pastures are invaded by longstyle feather grass (Parsons & Cuthbertson 1992)’.	ML	MH
Growth/Competitive
Life form?	Rhizomatous, erect densely tussock-forming perennial grass 30-70 cm high (Parsons & Cuthbertson 1992, Walsh & Entwisle 1994). Lifeform: Grass	MH	MH
Allelopathic properties?	No reference to allelopathy was found within the reasonably extensive literature of this species.	L	M
Tolerates herb pressure?	Young shoots may be eaten but the long serrated leaves of mature plants are unpalatable and rarely grazed by stock (Parsons & Cuthbertson 1992). Not favoured as fodder by stock (Walsh & Entwisle 1994).	MH	MH
Normal growth rate?	Establishment is slow, however once established can dominate infested pasture (Parsons & Cuthbertson 1992). Rate of growth and how it compares to other species of the same lifeform not clear from available information.	M	L
Stress tolerance to frost, drought, w/logg, sal. etc?	Displays tolerance to drought, as native to semi-arid areas, North Africa & the Arabian Peninsular (Parsons & Cuthbertson 1992), and described occurring in ‘dry places (Tutin et al 1980). Some tolerance to salt spray, as occurs in coastal areas and on islands (Edgar & Connor 2000, Parsons & Cuthbertson 1992) and tolerates temperatures to -1^oC (Dave's Garden 2008). May be tolerant of water logging, occurring in areas of run off, along creeks and riverbanks (Parsons & Cuthbertson 1992), and fire, being rhizomatous (Walsh & Entwisle 1994).	MH	M
Reproduction
Reproductive system	Reproducing by seed and from rhizomes (Parsons & Cuthbertson 1992). Both vegetative and sexual reproduction. Some references suggest establishment by seed is uncommon, with seedlings rarely surviving (Parsons & Cuthbertson 1992), while others indicate it is spreading quickly via seed (North West Weeds 2006).	H	MH
Number of propagules produced?	Prolific seeder (Parsons & Cuthbertson 1992). Images (Parsons & Cuthbertson 1992, P121) indicate could produce greater than 2,000 seeds per plant.	H	MH
Propagule longevity?	Propagule longevity not found documented.	M	L
Reproductive period?	Perennial (Walsh & Entwisle 1994). Strong rhizomatous growth often produces large dense clumps, increasing the size and density of existing colonies. Most new plants establish vegetatively with the development of shoots along the rhizomes (Parsons & Cuthbertson 1992). Extensive vegetative reproduction indicates colonies are likely to be self sustaining and/or produce propagules for 10+ years.	H	M
Time to reproductive maturity?	Seed germination occurs in early summer and flowering in late Summer (Parsons & Cuthbertson 1992), presumed to be the year after germination as establishment is described as slow (Parsons & Cuthbertson 1992). However, most reproduction is via vegetative means, with new shoots developing along rhizomes in the following Spring/Summer (Parsons & Cuthbertson 1992). Time to reproductive maturity appears to be greater than 1 year but less than 2 years.	MH	M
Dispersal
Number of mechanisms?	‘Major spread is the result of cultivation and road grading. Some seeds adhere to wool and fur of animals plus clothing bags and other fibrous material, and wind and water dispersal can occur (Parsons & Cuthbertson 1992)’.	MH	MH
How far do they disperse?	The above dispersal mechanisms (Parsons & Cuthbertson 1992) could spread propagules 200+ m.	MH	MH

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