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Invasiveness Assessment - Angled onion (Allium triquetrum) 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 Angled onion.

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 - 1026 KB)
To view the information PDF requires the use of a PDF reader. This can be installed for free from the Adobe website (external link).

Common Name: Angled onion
Scientific name: Allium triquetrum

Question
Comments
Reference
Rating
Establishment
Germination requirements?Seeds and bulbs germinate in autumn.
P & C (1992)
MH
Establishment requirements?Occurs in woodlands and ‘shady places’.
Carr et al (1992)
Tutin et al (1980)
MH
How much disturbance is required?Establishes in minor disturbed ecosystems (e.g. riparian, wetlands & woodlands), and pastures.
Carr et al (1992)
P & C (1992)
MH
Growth/Competitive
Life form?Bulbous perennial herb.

Geophyte.
P & C (1992)
ML
Allelopathic properties?None described.
L
Tolerates herb pressure?Consumed – response unknown. However, probably recovers quickly as it is noted as being z’ a very persistent weed which may take some time and intensive effort to completely eradicate”. (NCC).
MH
Normal growth rate?Does not compete strongly with crops and improved pastures.

Can completely smother and replace native ground cover vegetation.
P & C (1992)
NCC
MH
Stress tolerance to frost, drought, w/logg, sal. etc?Tolerant of water logging (occurs on poorly drained soils along watercourses). Also, assumed tolerant of frosts (occurs on slopes of Great Dividing Range and the Dandenong Ranges).
P & C (1992)
ML
Reproduction
Reproductive systemReproducing by seeds and bulbs.
P & C (1992)
H
Number of propagules produced?Probably < 50 seeds produced by each small bulb.
(See picture Hyde-Wyatt & Morris 1980 and O’Neill 1962).
Hyde-Wyatt (1980)
O’Neil (1962)
L
Propagule longevity??
M
Reproductive period?Provides a complete ground cover in some areas.
- forms monocultures.
P & C (1992)
H
Time to reproductive maturity?Year one - Seeds germinate.
Year two - Bulbs germinate.
Year three - Seeds produced by bulbs.
P & C (1992)
ML
Dispersal
Number of mechanisms?Agricultural produce, animals, machinery, vehicles, garden refuse and contaminated soil. Also insects and water.
P & C (1992)
NCC (1992)
MH
How far do they disperse?
MH


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