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Invasiveness Assessment - Artichoke thistle (Cynara cardunculus) 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 Artichoke 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 - 1026 KB)
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Common Name: Artichoke thistle
Scientific name: Cynara cardunculus
| Question | Comments | Reference | Rating |
| Establishment | |||
| Germination requirements? | “Seeds may germinate at any time of the year but most do so after autumn rain”. | P & C (1992) | H |
| Establishment requirements? | Requires ‘open’ areas e.g. pasture, gardens, wasteland, roadsides, vacant allotments. | P & C (1992) K & J (1997) | ML |
| How much disturbance is required? | Establishes in minor disturbed ecosystems (e.g. riparian, grassland) and well-established pastures. | P & C (1992) Carr et al (1992) | MH |
| Growth/Competitive | |||
| Life form? | Perennial herb. Other. | P & C (1992) Carr et al (1992) | L |
| Allelopathic properties? | None described. | L | |
| Tolerates herb pressure? | “The spiny nature of the plant deters sheep and cattle from grazing on heavy infestations but, when hungry, animals will eat the leaves”. | P & C (1992) | MH |
| Normal growth rate? | Can choke out or dominate vegetation of an area once established. | NSW Dept. Ag (1962) P & C (1992) | MH |
| Stress tolerance to frost, drought, w/logg, sal. etc? | Tolerance to salinity, presumably also drought (occurs in Ciza & Kalubia, Egypt & Australia). Water logging (occurs in irrigated and riparian areas) ? (Wernli & Tames 1984) | Giushniani et al (1999) Carr et al (1992) | MH |
| Reproduction | |||
| Reproductive system | Reproducing from a perennial taproot and by seed. | P & C (1992) | H |
| Number of propagules produced? | Approximately 16 inflorescence per plant x 100 florets per inflorescence x 1 seed per floret = approximately 1,600 seeds. About 16 heads on each plant but occasionally > 50 or more inflorescence 8 less florets | P & C (1992) | MH |
| Propagule longevity? | ? | M | |
| Reproductive period? | “Individual plants may live for many years”. Also, can form monocultures. (See pic. P & C 1992 p. 214). Carr et al (1992) also states that the plant forms ‘medium to large infestations’. | P & C (1992) | H |
| Time to reproductive maturity? | “Plants may flower in the first year but generally flowering is delayed until the second summer”. | P & C (1992) | H |
| Dispersal | |||
| Number of mechanisms? | Mostly seed dispersal – wind, animals, water, mud and birds. | P & C (1992) | H |
| How far do they disperse? | Seeds are usually blown within a few metres of the birds, plants. Animals, particularly birds and water are however likely to spread seeds farther. Small birds feed on seeds, perhaps dispersing seed > 200 m. | P & C (1992) | H |
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