Invasiveness Assessment - Trailing St John's wort (Hypericum humifusum) 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 Trailing St John's wort.
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: Trailing St John's wort
Scientific name: Hypericum humifusum
| Question | Comments | Confidence | Rating |
| Establishment | |||
| Germination requirements? | Insufficient documented evidence to determine germination / propagule requirements. Score medium. | M | L |
| Establishment requirements? | Found in open habitats (Tutin et al 1968). Locations where weed is found would indicate that it cannot establish under canopy. | ML | H |
| How much disturbance is required? | Found on hedgebanks and in coastal grassland. In Guernsey it is ‘common inland and on the cliffs, alongside the paths and on bareish rocky slopes in more accessible areas’ (La Societe Guernesiaise 2005). Widespread on heaths and moors. Establishes in minor disturbed natural ecosystems. | MH | MH |
| Growth/Competitive | |||
| Life form? | Glabrous perennial herb (Tutin et al 1968). Life form – other. | L | H |
| Allelopathic properties? | None described. In sufficient documentation on weed. Score a s medium. | M | L |
| Tolerates herb pressure? | Not enough documented evidence to determine ability to tolerate herbivory pressure. Score medium. | M | L |
| Normal growth rate? | Not enough documented evidence to determine normal growth rate of weed. Score medium. | M | L |
| Stress tolerance to frost, drought, w/logg, sal. etc? | Found in S. Sweden, S. Romania and N. Albania (Tutin et al 1968). Suggests frost tolerance. Grows in coastal grassland (La Societe Guernesiaise 2005). May be saline tolerant. Insufficient documented evidence to determine tolerance to drought, waterlogging and fire. Score medium. | M | L |
| Reproduction | |||
| Reproductive system | ‘The perennial plant propagates with underground buds from rhizomes or sometimes from root’. Can be grown as an annual (FNIAR 2001). Plant vegetatively reproduces but not enough information to determine whether sexually reproduces also. Score medium high. | MH | MH |
| Number of propagules produced? | Not enough documented evidence to determine propagules produced per flowering event. Score medium. | M | L |
| Propagule longevity? | No documented evidence on propagule longevity of weed but does vegetatively reproduce (FINIAR 2001). | L | L |
| Reproductive period? | Insufficient documented information on reproductive period of plant. Score medium. | M | L |
| Time to reproductive maturity? | Perennial but annual in crops (FNIAR 2001). Weed can reach maturity and produce viable propagules in under a year. | H | MH |
| Dispersal | |||
| Number of mechanisms? | Insufficient documented information to determine number of dispersal mechanisms. Score medium. | M | L |
| How far do they disperse? | Insufficient documented information to determine dispersal distance. Score medium. | M | L |
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