Invasiveness Assessment - Chinese rain tree (Koelreuteria elegans ssp. formosana) 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 Chinese rain tree.
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: Chinese rain tree
Scientific name: Koelreuteria elegans ssp. formosana
| Question | Comments | Rating | Confidence |
| Establishment | |||
| Germination requirements? | ‘Germinates in late winter’ (CRC for Australian Weed Management 2003). Requires natural seasonal temperatures for germination. | MH | M |
| Establishment requirements? | ‘.. successful germination of seed and subsequent growth of the seedling to maturity is dependent on the level of sunlight penetration’ However, can tolerate partial shade (CRC for Australian Weed Management 2003). | MH | M |
| How much disturbance is required? | In Brisbane, it has ‘invaded urban parks, bushland, gullies and streets’ (CRC for Australian Weed Management 2003). Establishes in highly disturbed natural ecosystems. | ML | M |
| Growth/Competitive | |||
| Life form? | Tree Life form – other. | L | MH |
| Allelopathic properties? | None described (PIER 2005). | L | M |
| Tolerates herb pressure? | No evidence to suggest that plant is affected by herbivores. | H | M |
| Normal growth rate? | ‘Growth rate: Fast .. minimum for a fast growing medium tree’ (PIER 2005). Moderately rapid growth that will equal competitive species of same life form | MH | MH |
| Stress tolerance to frost, drought, w/logg, sal. etc? | ‘It tolerates full sun, partial shade, drought, frost, heat, well drained to wet soils, extended flooding and air pollution. … may be tolerant of light salt spray, but not saline conditions’ (CRC for Australian Weed Management 2003). Highly tolerant of frost, drought and waterlogging. Susceptible to salinity. | MH | M |
| Reproduction | |||
| Reproductive system | Reproduces by seed (CRC for Australian Weed Management 2003). ‘As observed in .. K. elegans subsp. formosana, the flowers are entomophilous, bees and other small insects being the usual pollinators’ (Meyer 1976). | L | MH |
| Number of propagules produced? | ‘Fruits are up to 50 mm long and appear in large drooping clusters. The seeds are small, black and round and about 5 mm in diameter (CRC for Australian Weed Management 2003). ‘.. relatively large seed based on photo, two seed per fruit and roughly 100-200 seeds per panicle’ (PIER 2005). Trees likely to produce greater than 2,000 propagules per flowering event. | H | MH |
| Propagule longevity? | ‘Not known exactly how long seeds can survive in the soil .. experiments have shown that the seeds can achieve a 90-100% success rate of germination after 10 months of moist storage .. may be viable for some time’ (CRC for Australian Weed Management 2003). Insufficient information to determine longevity – score medium. | M | M |
| Reproductive period? | Insufficient information to determine length of reproductive period but would be greater than 3 years. Score as Medium High. | MH | L |
| Time to reproductive maturity? | Insufficient information to determine time to reach reproductive maturity. Score as Medium. | M | L |
| Dispersal | |||
| Number of mechanisms? | ‘Not known exactly how seeds are dispersed … possible that water may contribute, as supported by evidence of infestation of gullies in Brisbane….. birds may also be a factor in facilitating the spread’ (CRC for Australian Weed Management 2003). Insufficient evidence – score as medium. | M | M |
| How far do they disperse? | Insufficient information relating to dispersal. Score medium. | M | L |
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