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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. |
Question | Comments | Reference | Rating |
Establishment | |||
Germination requirements? | Seeds germinate mostly in autumn. | P&C (1992) | MH |
Establishment requirements? | Only known to occur in ‘open’ habitats. | Tutin et al (1968) P&C (1992) | ML |
How much disturbance is required? | Establishes in highly disturbed areas e.g. roadsides & waste places. | Webb et al (1988) | ML |
Growth/Competitive | |||
Life form? | Leguminous shrub. | P&C (1992) | MH |
Allelopathic properties? | None described. | L | |
Tolerates herb pressure? | “Although animals graze young shoots, they find established plants unacceptable b/c of the spines.” | P&C (1992) | MH |
Normal growth rate? | M | ||
Stress tolerance to frost, drought, w/logg, sal. etc? | M | ||
Reproduction | |||
Reproductive system | Reproducing by seed. | P&C (1992) | M |
Number of propagules produced? | M | ||
Propagule longevity? | M | ||
Reproductive period? | M | ||
Time to reproductive maturity? | Plants rarely flowering before they are 2-3 years old. | P&C (1992) | ML |
Dispersal | |||
Number of mechanisms? | Seeds ejected from pod, also equipment, machinery, produce, animals, mud, etc. Also by clothes, water & in chaff, hay, grain & silage. | P&C (1992) Anon | MH |
How far do they disperse? | M |