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Invasiveness Assessment - Glaucous star thistle (Carthamus glaucus) 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 Glaucous star thistle.

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)
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: Glaucous star thistle
Scientific name: Carthamus glaucus

Question
Comments
Rating
Confidence
Establishment
Germination requirements?Insufficient information to determine germination requirements for C. glaucus, although C. lanatus seeds germinate after autumn rains. Score medium.
M
L
Establishment requirements?Can occur as a weed of agriculture (Solh & Pala 1990). Known to occur out in the open but not
documented as to whether it can establish under a canopy. Insufficient evidence. Score medium.
M
L
How much disturbance is required?Can occur as a weed of agriculture in chickpea (Solh & Pala 1990). Also known to grow with wild emmer wheat in Israel. Establishes in vigorously growing crops.
MH
H
Growth/Competitive
Life form?Annual herb (Walsh & Entwisle 1999). Life form – other.
L
H
Allelopathic properties?None described. Little information on weed.
M
L
Tolerates herb pressure?Acanthiophilus helianthi (a serious pest of safflower in Egypt) also uses C. glaucus as an alternative foodplant (Hegazi & Moursi 1983). Not enough documented evidence to determine tolerance to herbivory pressure.
M
L
Normal growth rate?Not enough documented evidence to determine normal growth rate of weed.
M
L
Stress tolerance to frost, drought, w/logg, sal. etc?Not enough documented evidence to determine stress tolerance of weed. Score medium.
M
L
Reproduction
Reproductive systemPlant reproduces by seed. Not enough evidence to determine if reproduces by cross or self-pollination or both. Score as low.
L
M
Number of propagules produced?Not enough documented evidence to determine number of propagules produced. Score medium.
M
L
Propagule longevity?Not enough documented evidence to determine propagule longevity of plant. Score medium.
M
L
Reproductive period?Annual herb (Walsh & Entwisle 1999). Mature plant produces viable propagules for only one year.
L
H
Time to reproductive maturity?Annual herb (Walsh & Entwisle 1999). Reaches maturity and produces viable propagules in under a year.
H
H
Dispersal
Number of mechanisms?Seeds have a pappus (Walsh & Entwisle 1999). Would indicate that propagules may be wind dispersed but insufficient supporting documentary evidence. Score medium.
M
H
How far do they disperse?Not enough documented evidence to determine dispersal distance. Score medium.
M
L


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