Invasiveness Assessment - Fennel (Foeniculum vulgare) 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 Fennel.
A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:
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Common Name: Fennel
Scientific name: Foeniculum vulgare
| Question | Comments | Reference | Rating |
| Establishment | |||
| Germination requirements? | “Seeds germinate at almost any time of the year”. | P & C (1992) | H |
| Establishment requirements? | “It grows best in open, unshaded situations”. | P & C (1992) | ML |
| How much disturbance is required? | Establishes in minor disturbed natural ecosystems (e.g. riparian vegetation and grasslands), crops and pastures. | Carr et al (1992) Blood | MH |
| Growth/Competitive | |||
| Life form? | Perennial herb – above ground material dies and re grows from crown each spring, therefore geophyte. | P & C (1992) | ML |
| Allelopathic properties? | Possible allepathic properties as many vegetables and herbs do not grow in association with fennel. | P & C (1992) | ML |
| Tolerates herb pressure? | Consumed: still assumed to be capable of vegetative propagule production (crown/root fragments), so may persist. | P & C (1992) | ML |
| Normal growth rate? | Fennel excludes almost all other vegetation. “Able to out compete small native understorey shrubs and groundcover plants”. | Northcote City Council P & C (1992) | H |
| Stress tolerance to frost, drought, w/logg, sal. etc? | Tolerant of frost, water logging, semi aridity. | P & C (1992) | MH |
| Reproduction | |||
| Reproductive system | Reproducing by seed, from the crown and pieces of crown and root. | P & C (1992) | H |
| Number of propagules produced? | (Estimate based on pic. in Butcher 1961). 10 inflorescence x 16 umbels x 100 seeds/umbel = 16,000 seeds/plant. | Butcher (1961) | H |
| Propagule longevity? | ? |  | M |
| Reproductive period? | May form dense monocultures (see pic. P & C (1992) p. 171). | P & C (1992) | H |
| Time to reproductive maturity? | “Plants generally do not flower until 18 months to 2 years old. | P & C (1992) | MH |
| Dispersal | |||
| Number of mechanisms? | Crown and root dragged by equipment and machinery. Seeds spread by vehicles, machinery, animals (external), clothing, water, etc. also wind. (Blood n.d.). | P & C (1992) | MH |
| How far do they disperse? | Many will disperse > 200 m, especially through earth movement, stock, water and wind. | P & C (1992) Blood (n.d.) | MH |
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© The State of Victoria, 1996 - 2009.
This document was last reviewed on 18/08/2009