Invasiveness Assessment - Perennial veldt grass (Ehrharta calycina) 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 Perennial veldt grass.
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: Perennial veldt grass
Scientific name: Ehrharta calycina
| Question | Comments | Rating | Confidence |
| Establishment | |||
| Germination requirements? | Seeds germinated from 13oC to 28oC under light and dark conditions, suggesting that germination could occur at any time of the year as long as moisture is available (Smith et al. 1999). | H | H |
| Establishment requirements? | “Observed growing under a wide variety of light, temperature, moisture and substrate conditions including…forest edges, shrublands with some shade, and in the forest understorey (Frey 2005). Can establish without additional factors, under full canopy cover. | H | MH |
| How much disturbance is required? | Commonly invades highly disturbed ecosystems, such as sand dunes, sparse pasture, roadsides and plantations (Frey 2005), and also capable of invading less disturbed ecosystems such as woodlands (Smith et al. 1999) and open mallee and forest, however this is probably only occurring in vegetation gaps (Virtue & Melland 2003). Establishes in highly disturbed natural ecosystems and patchy pasture/crops. | ML | MH |
| Growth/Competitive | |||
| Life form? | Perennial grass (Smith et al. 1999). | L | H |
| Allelopathic properties? | In D’Antonio & Vitousek (1992) the invasiveness of this species in several countries is described in some detail, but the section dealing with allelopathy does not mention E. calycina. No reference to allelopathic properties of this species was found. | L | MH |
| Tolerates herb pressure? | Introduced as a forage crop, however, grazing can reduce populations and may eliminate them over 3 years of normal stocking rates (Frey 2005). Eliminated by moderate herbivory. | L | MH |
| Normal growth rate? | Rapid growth rate (Pickart 2007) that will exceed most other grass species. | H | M |
| Stress tolerance to frost, drought, w/logg, sal. etc? | Established plants resprout vigorously from the base of the tussock after summer drought in WA, and may provide some tolerance to fire, but regular controlled burns would probably reduce its invasability (Smith et al. 1999). Does not tolerate waterlogging (Frey 2005). Tolerates temperatures to at least -8oC, “low” salinity tolerance; tolerant to 2.1-4.0 dS/m (Pickart 2007). Highly tolerant of drought and frost. Some fire tolerance. Does not tolerate waterlogging or high salinity. | MH | MH |
| Reproduction | |||
| Reproductive system | The Ehrharta perennials reproduce both by seed and vegetatively (expanding tussocks) (Frey 2005); rhizomatous (Virtue & Melland 2003). | H | MH |
| Number of propagules produced? | Described as a prolific seeder, and soil seed bank densities were found to be at the upper end of figures for grasslands and arable fields (Smith et al. 1999). Seed yield was measured, and averaged 140 seeds per panicle, from the 31 panicles harvested (Rossiter 1947) = at least 4,340 seeds per plant. | H | H |
| Propagule longevity? | Seeds of this species germinated from topsoil that had been stored for 3 years (Rokich et al 2000). No further information found. | M | L |
| Reproductive period? | Short lifespan (Pickart 2007), generally 3 to 7 years (Rossiter 1947), but with a “demonstrated capacity to form understorey monocultures in remnant native vegetation in SA” (Virtue & Melland 2003). | H | MH |
| Time to reproductive maturity? | “Produces seed in the first year of growth” (Virtue & Melland 2003). | H | MH |
| Dispersal | |||
| Number of mechanisms? | “Seeds are dispersed locally by wind and may occasionally be carried on animal fur” (Frey 2005). | MH | MH |
| How far do they disperse? | Seeds are dispersed by wind (Frey 2005), but long-distance spread by wind is unlikely (Virtue & Melland 2003). Occasional dispersal on animal fur (Frey 2005) may spread few propagules to one kilometre, but most are likely to spread less than 20 m. | L | MH |
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