Invasiveness Assessment - Onion weed (Asphodelus fistulosus) in Victoria (Nox)

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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 Onion weed.

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: Onion weed
Scientific name: Asphodelus fistulosus

Question	Comments	Reference	Rating
Establishment
Germination requirements?	Seeds germinate at almost any time of the year.	P & C (1992)	H
Establishment requirements?	Establishes in ‘open’ areas e.g. roadsides, pastures and cultivated land.	P & C (1992) Feldoldi	ML
How much disturbance is required?	Establishes most readily in disturbed situations, e.g. roadsides and overgrazed pastures but does not dominate in well-maintained pastures. Establishes minor disturbed ecosystems. (Carr et al 1992).	P & C (1992)	MH
Growth/Competitive
Life form?	An erect annual biennial or perennial herb. Other.	P & C (1992)	L
Allelopathic properties?	None described.		L
Tolerates herb pressure?	Not eaten by stock or ‘seldom’ eaten by stock.	P & C (1992) Meadly	MH
Normal growth rate?	“onion weed does not invade areas successfully when competing for moisture with perennial plants that have roots close to the surface”…BUT, in disturbed/other situations it ‘grows so thickly that other vegetation, particularly grasses, is reduced’.	P & C (1992)	MH
Stress tolerance to frost, drought, w/logg, sal. etc?	Drought – hardy once established. Assumed also tolerant to frosts (occurs in Southern Tasmania where frost occur).	P & C (1992) See dist. Map	MH
Reproduction
Reproductive system	Reproducing by seed.	P & C (1992)	ML
Number of propagules produced?	80 flowers per plant x 6 seeds per flower = 480 seeds per plant. (See Felfoldi & Meadly).	Felfoldi Meadly	ML
Propagule longevity?	Seeds remain viable in the soil for many years”.	P & C (1992)	M
Reproductive period?	Some plants flower and die in the first year thus becoming annuals, others are biennials or short-lived perennial. (At least three years).	P & C (1992)	MH
Time to reproductive maturity?	Young plants develop slowly and generally do not flower until they are about 18 moths old. Annual species.	P & C (1992)	H
Dispersal
Number of mechanisms?	Vehicles, machinery, animals, wool, clothing, produce and water, wind blowing dead plants still bearing seeds.	P & C (1992)	MH
How far do they disperse?	Vehicles, machinery, animals, humans, water and wind are likely to disperse propagules > 200 m. however, main dispersal mechanisms is wind blowing dead plants.		MH

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