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)
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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 system | Plant 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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