Invasiveness Assessment - Soldier thistle (Cirsium acarna) 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 Soldier 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: Soldier thistle
Scientific name: Cirsium acarna
| Question | Comments | Reference | Rating |
| Establishment | |||
| Germination requirements? | Seeds germinate after autumn rains. | P & C (1992) | MH |
| Establishment requirements? | Habitat is “open” areas e.g. roadsides, crop/pasture areas. | P & C (1992) Tutin et al (1976) | ML |
| How much disturbance is required? | Establishes in vigorously growing crops (e.g. cereal crops) & pastures. | P & C (1992) Web Page | MH |
| Growth/Competitive | |||
| Life form? | An erect annual herb. “Other”. | P & C (1992) | L |
| Allelopathic properties? | None described. |  | L |
| Tolerates herb pressure? | Avoided by stock. | P & C (1992) | MH |
| Normal growth rate? | “Competes with crops” – (P & C 1992). “Crop & pasture competition” (Web Page). | P & C (1992) Web Page | MH |
| Stress tolerance to frost, drought, w/logg, sal. etc? | | | M |
| Reproduction | |||
| Reproductive system | Reproducing by seed. | P & C (1992) | ML |
| Number of propagules produced? | Lack of descriptive information. However likely high. (See picture P & C (1992) page 223-24). | | M |
| Propagule longevity? | ? | | M |
| Reproductive period? | Annual. | | L |
| Time to reproductive maturity? | Seeds germinate after autumn rains – Flowering early summer. | P & C (1992) | H |
| Dispersal | |||
| Number of mechanisms? | Wind, wool, hides, vehicles, mud and water. | P & C (1992) | MH |
| How far do they disperse? | Pappus would aid wind dispersal. Many would disperse > 200 m, particularly plants growing along channels (allowing for water dispersal), as plants often grow along channel banks. | P & C (1992) | MH |
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