Invasiveness Assessment - Saffron thistle (Carthamus lanatus) 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 Saffron 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: Saffron thistle
Scientific name: Carthamus lanatus
| Question | Comments | Reference | Rating |
| Establishment | |||
| Germination requirements? | Seeds germinate in autumn & early winter. | P&C (2001) | MH |
| Establishment requirements? | Occurs in mostly ‘open’ areas e.g. paddocks, grasslands. | P&C (2001) Carr et al (1992) | ML |
| How much disturbance is required? | Weed in cultivated paddocks. Invades lowland grassland & grassy woodland. | P&C (2001) Carr et al (1992) | MH |
| Growth/Competitive | |||
| Life form? | Annual herb → Other. | P&C (2001) | L |
| Allelopathic properties? | Allelopathic properties not described. |  | L |
| Tolerates herb pressure? | Has little fodder value although it is eaten to some extent when very young and later as the stem emerges from the rosette. | P&C (2001) | MH |
| Normal growth rate? | In crops, competition reduces yield…does not invade perennial pastures nor does it withstand competition from improved annual pastures. | P&C (2001) | MH |
| Stress tolerance to frost, drought, w/logg, sal. etc? | Tolerance to frost & drought (See Australian distribution). | P&C (2001) | M |
| Reproduction | |||
| Reproductive system | Reproducing by seed. | P&C (2001) | ML |
| Number of propagules produced? | Individual seed heads can produce 10-16 seeds. 8 seed heads/plant x 16 seeds/head = 128 seeds/plant. | Groves et al (1995) | ML |
| Propagule longevity? | Some survived for up to 8 years but most seemed to be destroyed by bacteria, fungi or termites. | P&C (2001) | L |
| Reproductive period? | Annual her. Forms dense infestations (see pick p196) yet doesn’t appear to be a monoculture. | P&C (2001) | L |
| Time to reproductive maturity? | Annual herb. | P&C (2001) | H |
| Dispersal | |||
| Number of mechanisms? | Seed spread by clothing, bags, wool, fur, mud stuck to implements & vehicles, ‘tumbleweed’ effect & the flow of water along channels. | P&C (2001) | MH |
| How far do they disperse? | The dried seed heads tangle in wool & the whole plant breaking off at the base, acts as a ‘tumbleweed’ spreading the seed over long distances. | P&C (2001) | MH |
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