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Invasiveness Assessment - Chinese violet (Asystasia gangetica ssp. micrantha) 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 violet.

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: Chinese violet
Scientific name: Asystasia gangetica ssp. micrantha

Question
Comments
Rating
Confidence
Establishment
Germination requirements?‘In tropical climates plant growth is probably continuous, especially in moist conditions or following rainfall’. ‘Forms roots when the nodes make contact with moist soil’ (CRC for Australian Weed Management 2003). Opportunistic germinator.
H
M
Establishment requirements?‘Forms roots when the nodes make contact with moist soil (CRC for Australian Weed Management 2003). ‘Prefers full sun or part shade. Plants in deep shade do not thrive’. ‘If established underneath a hedge it often comes up through the hedge by leaning its weak stems on the shrub’s branches’ (Whistler 2000 cited in PIER 2005). Although the weed prefers sun, can establish under a moderate canopy.
MH
MH
How much disturbance is required?‘Most infestations .. occur on vacant residential land, along fencelines and in neglected garden beds .. present along roadsides and on crown land’ (CRC for Australian Weed Management 2003). Establishes in highly disturbed natural ecosystems.
MH
M
Growth/Competitive
Life form?A perennial creeper (CRC for Australian Weed Management 2003).
ML
M
Allelopathic properties?None described.
L
M
Tolerates herb pressure?Where Asystasia gangetica is present in Malaysia it has been found that ‘strip-grazing sheep in a weed infested rubber plantation markedly reduced weed height (to 10 cm above the soil) after 3 grazing cycles. The sheep preferentially selected Asystasia spp. before passing on to other weeds ’ (Abdullah 1985).

‘High stocking rates (>6 sheep/ ha) resulted in a decrease in the proportion of palatable species, namely,
Asystasia gangetica.’ (Chong et al 1997). Consumed and recovers slowly.
ML
MH
Normal growth rate?‘.. a perennial creeper that grows rapidly’ (CRC for Australian Weed Management 2003). Assume that weed has moderately rapid growth rate that will equal competitive species of the same life form.
MH
M
Stress tolerance to frost, drought, w/logg, sal. etc?‘Winter frosts kill the above-ground plant parts but plants regrow the following spring from basal shoots’ (CRC for Australian Weed Management 2003). ‘Found on coastal sandy soils’ (Whistler 2000 cited in PIER 2005). ‘It can withstand drought.’
MH
MH
Reproduction
Reproductive systemProduces through seed and rhizomes (PIER 2005). Produces both sexually and vegetatively.
H
MH
Number of propagules produced?Each seed capsule ‘contain four flattened seeds’. ‘High seed production’ (CRC for Australian Weed Management 2003). No documentation on number of capsules per plant. Score medium.
M
M
Propagule longevity?‘ seeds remain dormant for some months .. if the seed coat is removed, about 75% germinate’ (Akamine 1947). Assume that seeds survive less than 5 years.
L
MH
Reproductive period?‘ .. the plant dies back to ground level after most of the ripe capsules have released their seeds’ (CRC for Australian Weed Management 2003). No documentation on the reproductive period of the plant. Score as medium.
M
M
Time to reproductive maturity?‘ it grows rapidly following germination and throughout flowering and seed capsule production’ (CRC for Australian Weed Management 2003). PIER (2005) states that can be grown as an annual.
H
MH
Dispersal
Number of mechanisms?‘The main method of dispersal over long distances is by human activities, such as mining, gardening, landscaping and roadworks. Propagules can spread by light vehicular traffic (CRC for Australian Weed Management 2003).
MH
M
How far do they disperse?‘The main method of dispersal over long distances is by human activities, such as mining, gardening, landscaping and roadworks' (CRC for Australian Weed Management 2003). Without further documentation, assume few propagules will disperse greater than 1 km but many will reach 200-1,000 m.
MH
M


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