Invasiveness Assessment - Poverty weed (Iva axillaris) 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 Poverty weed.
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 - 1 MB)
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Common Name: Poverty weed
Scientific name: Iva axillaris
| Question | Comments | Reference | Rating |
| Establishment | |||
| Germination requirements? | “Seeds are thought to germinate in spring, about the same time that shoots develop from the root system.” Requires natural seasonal disturbance to germinate. | Parsons & Cuthbertson (2001) | MH |
| Establishment requirements? | It prefers alkaline, poorly drained soils. In Australia, it occurs in a few areas on cultivated land and pastures. Requires open areas with access to sunlight and moisture. | Parsons & Cuthbertson (2001) | ML |
| How much disturbance is required? | In California, U.S., the plant occurs on, “… alkaline plains, edges of salt marshes, cultivated fields, pastures, roadsides [and] waste places.” Establishes in highly disturbed ecosystems. | CDFA | ML |
| Growth/Competitive | |||
| Life form? | Perennial herb, reproducing from creeping roots and seed. Geophyte. | Parsons & Cuthbertson (2001) | ML |
| Allelopathic properties? | “Poverty weed is allelopathic; extracts from the leaves reduce germination and root and shoot development of wheat, and root extracts inhibit growth of several grasses and legumes.” Allelopathic properties seriously affecting some plants. | Parsons & Cuthbertson (2001) | MH |
| Tolerates herb pressure? | “… it is seldom grazed because of its strong smell and taste.” Not eaten. | Parsons & Cuthbertson (2001) | H |
| Normal growth rate? | Iva axillaris competes strongly with cereal crops. No records exist of its competitiveness with other weedy perennials. It develops new growth in spring and matures and flowers in summer. Its growth rate may exceed other species of the same life form. | Parsons & Cuthbertson (2001) | H |
| Stress tolerance to frost, drought, w/logg, sal. etc? | “Food reserves in the deep roots allow new growth to develop in drought years.” The plant occurs on saline soils and the deep root system may ensure it survive periods of frost. “… poverty weed… is a natural component of many grassland communities that experience periodic fire.” Able to survive fire. | Parsons & Cuthbertson (2001) CDFA | MH |
| Reproduction | |||
| Reproductive system | Reproduces from creeping roots and seed. | Parsons & Cuthbertson (2001) | H |
| Number of propagules produced? | About 6 or 7 seeds produced in each flower head, of which there are many on each stem. Stems numerous. Possibly more than 2,000 seeds per plant. | Parsons & Cuthbertson (2001) | H |
| Propagule longevity? | Little is known of the viability or longevity of seed. In the U.S., “… studies have shown some seed may be viable after two years of freshwater storage.” | CDFA | L |
| Reproductive period? | “Poverty weed is a long-lived perennial.” | Parsons & Cuthbertson (2001) | MH |
| Time to reproductive maturity? | Seeds germinate in spring; plants mature in summer producing flowers and seed. Mature in under one year. | Parsons & Cuthbertson (2001) | H |
| Dispersal | |||
| Number of mechanisms? | The seed is not equipped with a pappus, so is not adapted to wind dispersal. It can contaminate agricultural produce, seed, machinery and can survive c. 8 months submerged in water. Within a property dispersal can occur through the distribution of root fragments on cultivation equipment. | Parsons & Cuthbertson (2001) CDFA | MH |
| How far do they disperse? | Much of the spread of this plant is due the creeping roots. In Canada viable seed is seldom produced. This may also be the case in Australia, where the current infestation has not spread. The main method of spread may be on contaminated agricultural machinery; thus, dispersal would be limited to less than 1 kilometre. | Parsons & Cuthbertson (2001) | MH |
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