Invasiveness Assessment - Tangled hypericum (Hypericum triquetrifolium) 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 Tangled hypericum.
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: Tangled hypericum
Scientific name: Hypericum triquetrifolium
| Question | Comments | Reference | Rating |
| Establishment | |||
| Germination requirements? | “Seeds germinate in autumn and root growth during winter is rapid” It occurs in areas with winter dominant rainfall. Requires natural seasonal disturbance (rainfall) to germinate & grow. | MH | |
| Establishment requirements? | Requires winter rainfall to stimulate growth in established plants. It occurs on open woodlands, so may tolerate some degree of shading. | Parsons & Cuthbertson (2001) | MH |
| How much disturbance is required? | “In Australia, it has very limited occurrence as a weed of open woodlands encroaching onto grazing land.” Establishes in relatively intact habitats (i.e. open woodland). | Parsons & Cuthbertson (2001) | MH |
| Growth/Competitive | |||
| Life form? | Perennial herb. Reproduces from rhizomes. Geophyte. | Parsons & Cuthbertson (2001) | ML |
| Allelopathic properties? | None reported |  | L |
| Tolerates herb pressure? | As with H. perforatum, grazing animals may consume tangled hypericum. Although flowering stems may be consumed, the plant is a perennial with rhizomes, which would ensure survival of the plant. Weed may persist. | Parsons & Cuthbertson (2001) | ML |
| Normal growth rate? | A winter growing species with deep vertical roots and horizontal rhizomes, it grows rapidly. “Where established in Victoria, it has eliminated most other vegetation.” Exceeds growth of other species of similar life form. | Parsons & Cuthbertson (2001) | H |
| Stress tolerance to frost, drought, w/logg, sal. etc? | No information is recorded for this species, however, as it is a deep-rooted perennial and occurs in subhumid, semi-arid warm-temperate to subtropical regions, it may tolerate drought. Additionally, the deep root system may ensure the plant can survive fire. It is known to occur near Dunolly in Victoria, which is subject to low winter temperatures and possibly frost. | Parsons & Cuthbertson (2001) BOM | ML |
| Reproduction | |||
| Reproductive system | Reproduces vegetatively and sexually. | Parsons & Cuthbertson (2001) | H |
| Number of propagules produced? | Not documented. The related H. perforatum produces up to 33,000 seeds p.a. Likewise, H. triquetrifolium may produce a large number of seeds (i.e. > 2000) annually. | Parsons & Cuthbertson (2001) | H |
| Propagule longevity? | Not recorded | | M |
| Reproductive period? | Not documented. Other Hypericum species live for several years. | Parsons & Cuthbertson (2001) | MH |
| Time to reproductive maturity? | “Seeds germinate in autumn… stems develop in spring and the first flowers are produced by early summer.” Reproduces in less than one year. | Parsons & Cuthbertson (2001) | H |
| Dispersal | |||
| Number of mechanisms? | Seeds are not equipped in any special way to aid dispersal. Spread can due to seeds or vegetative material occurring in contaminated agricultural produce, vehicles, farm machinery, water, mud and fodder. | Parsons & Cuthbertson (2001) | MH |
| How far do they disperse? | Most seeds fall at the base of the parent plant. Some seed may disperse up to one kilometre, though most will be about 20 to 200 metres. | Parsons & Cuthbertson (2001) | ML |
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