Invasiveness Assessment - Hairy thornapple (Datura wrightii) 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 Hairy thornapple.

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: Hairy thornapple
Scientific name: Datura wrightii

Question	Comments	Rating	Confidence
Establishment
Germination requirements?	In its native range seeds germinate during the winter rains (Hare & Smith 2005). In Australia can germinate throughout the year if has adequate soil moisture (Parsons & Cuthbertson 2001).	H	MH
Establishment requirements?	Reported in scrubland therefore able to establish under moderate shading (Elle & Hare 2000).	MH	MH
How much disturbance is required?	Most frequently found in areas of high disturbance, including roadsides, stock camps and under cultivation (Parsons & Cuthbertson 2001). In its native range reported in riparian forest (Calflora 2006).	M	MH
Growth/Competitive
Life form?	Perennial herb (Parsons & Cuthbertson 2001).	L	MH
Allelopathic properties?	Not reported for this species, however D.stramonium has been reported to have allelopathic effects (Parsons & Cuthbertson 2001).	M	L
Tolerates herb pressure?	Herbivory by insects can decrease seed production (Elle & Hare 2000). Toxic with a unpleasant odour and therefore avoided, however cattle have been known to eat large amounts during drought with no ill effect (Parsons & Cuthbertson 2001).	MH	MH
Normal growth rate?	Competitive with summer-growing crop species (Parsons & Cuthbertson 2001).	H	MH
Stress tolerance to frost, drought, w/logg, sal. etc?	Occurs in desert areas, therefore drought tolerant (Raguso et al 2003). Senesces during the winter, to then regrow from rootstock, therefore frost tolerant (Hare & Smith 2005). Can occur in ephemeral streambeds, therefore tolerant of waterlogging (Hare & Elle 2004).	H	MH
Reproduction
Reproductive system	Seeds, can be cross pollinated by a hawkmoth or be self pollinated. Flowers are often only open for one day (Hare & Smith 2005).	ML	H
Number of propagules produced?	Plants capable of producing 14,000 viable seeds, most appear to produce less hover still more than 2000 (Hare & Elle 2004).	H	H
Propagule longevity?	Seeds of a similar species D.stramonium have been found to be viable after being buried for 39 years (Parsons & Cuthbertson 2001).	H	M
Reproductive period?	Most plants die after three years (Hare & Elle 2004).	M	H
Time to reproductive maturity?	Can flower and set seed with in first year (Hare & Smith 2005).	H	H
Dispersal
Number of mechanisms?	Seeds and seed capsules float (water), also spread through seed and fodder contamination (Parsons & Cuthbertson 2001). Thorny seed capsules could also attach to animals.	MH	MH
How far do they disperse?	Water is capable of spreading seeds kilometres	MH	M

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