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Datura inoxia Risk Assessment

Common names: pricklyburr

Datura inoxia -- California

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Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
June 2, 2016
Evaluation Time (hrs): 
2 Hours
Evaluation Status: 
Completed
Plant Information
Plant Material: 
If the plant is a cultivar, and if the cultivar's behavior differs from its parent's (behavior), explain how: 
Regional Information
Region Name: 
Climate Matching Map
These maps were built using a toolkit created in collaboration between GreenInfo Network, PlantRight, Cal-IPC, and Agricultural Sustainability Institute at UC Davis.
Climate Matching Maps PDF: 
Invasive History and Climate Matching
1. Has the species (or cultivar or variety, if applicable; applies to subsequent "species" questions) become naturalized where it is not native?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Widely naturalized (GRIN). Naturalized in Madagascar (efloras). Has naturalized across the United States, Europe, Asia and other parts of the world (Learn 2 Grow).
Reference(s): 
2. Is the species (or cultivar or variety) noted as being naturalized in the US or world in a similar climate?
Yes or No: 
Yes
Points: 
2
Confidence Level: 
Answer / Justification: 
Widely naturalized (GRIN). Naturalized in Madagascar (zones 10a-13b) (efloras). Has naturalized across the United States, Europe, Asia and other parts of the world (Learn 2 Grow). Overlap with California's Climate Zones (Cal-IPC).
Reference(s): 
3. Is the species (or cultivar or variety) noted as being invasive in the U.S. or world?
Yes or No: 
Yes
Points: 
2
Confidence Level: 
Very High
Answer / Justification: 
Invasive in China (all zones 1a-11b), Ecuador (zones 10a-13b), Taiwan (zones 9a-11b) (PIER). “Thornapples…are of most importance in Queensland and northern New South Wales where they compete with many crops. Mung beans and soybeans are seriously affected and yield losses of up to 90% have been recorded.” Serious impact on quantity. Primarily a weed of cropping, control can be achieved by repeated cultivations. Thornapple plants produce a large amount of seed and seeds remain viable for more than 30 years, therefore, control is a long-term exercise. With the serious impact this plant can have on agricultural production and the time to control or eradicate it, land values may be greatly affected (Victoria zones 7a-9b) (Victorian Invasive Plants). Widely distributed weed of disturbed land. A weed of summer crops (Weeds Australia).
Reference(s): 
4. Is the species (or cultivar or variety) noted as being invasive in the US or world in a similar climate?
Yes or No: 
Yes
Points: 
3
Confidence Level: 
Very High
Answer / Justification: 
Invasive in China (all zones 1a-11b), Ecuador (zones 10a-13b), Taiwan (zones 9a-11b) (PIER). “Thornapples…are of most importance in Queensland and northern New South Wales where they compete with many crops. Mung beans and soybeans are seriously affected and yield losses of up to 90% have been recorded.” Serious impact on quantity. Primarily a weed of cropping, control can be achieved by repeated cultivations. Thornapple plants produce a large amount of seed and seeds remain viable for more than 30 years, therefore, control is a long-term exercise. With the serious impact this plant can have on agricultural production and the time to control or eradicate it, land values may be greatly affected (Victoria zones 7a-9b) (Victorian Invasive Plants). Widely distributed weed of disturbed land. A weed of summer crops (Weeds Australia). Substantial overlap with California climate zones (Cal-IPC).
Reference(s): 
5. Are other species of the same genus (or closely related genera) invasive in a similar climate?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
D. stramonium is a weed of disturbed areas and summer crops in Australia (zones 8a-13b); D. tatula is a purple form of this species (Weeds Australia). D. stramonium is weedy (Learn 2 Grow). D. ferox and D. metel (possibly synonym for D. inoxia) are weeds in Australia (PIER). D. stramonium is a weed in California (UC IPM). Obvious clear overlap with California's climate zones (Cal-IPC).
Reference(s): 
6. Is the species (or cultivar or variety) found predominately in a climate matching the region of concern?
Yes or No: 
Yes
Points: 
2
Confidence Level: 
Very High
Answer / Justification: 
Distributed extensively in the southern US, South America, Africa (particularly western and southern regions, and some in the eastern region near Kenya), densely in the Mediterranean region, throughout Australia, and sporadically elsewhere (GBIF). Thorn apple (recurved) prefers warm-temperate and sub-tropical regions, mainly in open, warm situations and on fertile soils. It is often found on river flats, stock yards and competes strongly with summer crops. The weed is tolerant of water logging and drought (Agriculture Victoria). Clearly overlaps substantially with California's climate zones, and grows primarily in areas matching California's Climate Zones (e.g., Mediterranean regions, and California) (Cal-IPC).
Reference(s): 
Impact on Native Plants and Animals
7. Does this plant displace native plants and dominate (overtop or smother) the plant community in areas where it has established?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Compete strongly with summer species for moisture and nutrient. Not known as a serious weed of natural ecosystems. Major displacement of annual grasses/ground covers. “Dense infestations occur in pastures and on river flats, producing a complete ground cover.” Likely to have a major impact on plants in the lower stratum (Victorian Invasive Plants). Thorn apple (recurved) competes strongly with summer species for moisture and nutrients. Although it displaces annual grasses, ground cover and riparian vegetation, it is not known to be a serious weed of natural ecosystems. Dense infestations occur in pastures and on river flats, producing a complete ground cover. The plants die in the cooler autumn weather. However, dead plants bear capsules that may remain standing through winter into spring (Agriculture Victoria). While perhaps not dominant year-round, can dominate plant communities in the summer at the very least, and standing skeletons may alter plant communities.
Reference(s): 
8. Is the plant noted as promoting fire and/or changing fire regimes?
Yes or No: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
The plants die in the cooler autumn weather, but dead plants bearing capsules may remain standing through winter into spring.” Potential for a minor change in the frequency of fire risk within dense patches (Victorian Invasive Plants). An exhaustive Google/Google Scholar search did not reveal any additional evidence of this and the question defaults to a “no” answer at this time.
Reference(s): 
9. Is the plant a health risk to humans or animals/fish? Has the species been noted as impacting grazing systems?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
All parts of the plant are poisonous; covered with numerous slender spines. All parts of Datura plants contain dangerous levels of poison and may be fatal if ingested by humans and other animals, including livestock and pets (EOL). All Datura plants contain tropane alkaloids such as scopolamine, hyoscyamine, and atropine, primarily in their seeds and flowers. Because of the presence of these substances, Datura has been used for centuries in some cultures as a poison. There can be a 5:1 toxin variation between plants and a given plant's toxicity depends on its age, where it is growing, and the local weather conditions. These variations makes Datura exceptionally hazardous as a drug. In traditional cultures, a great deal of experience with and detailed knowledge of Datura was critical to minimize harm. Many tragic incidents result from modern users ingesting Datura. For example, in the 1990s and 2000s, the United States media contained stories of adolescents and young adults dying or becoming seriously ill from intentionally ingesting Datura. There are also several reports in the medical literature of deaths from D. stramonium and D. ferox intoxication. Children are especially vulnerable to atropine poisoning. Datura toxins may be ingested accidentally by consumption of honey produced by several wasp species, including Brachygastra lecheguana, during the Datura blooming season. It appears that these semi-domesticated honey wasps collect Datura nectar for honey production which can lead to poisoning. In some parts of Europe and India, Datura has been a popular poison for suicide and murder. From 1950 to 1965, the State Chemical Laboratories in Agra, India, investigated 2,778 deaths caused by ingesting Datura. The US Centers for Disease Control and Prevention reported accidental poisoning resulting in hospitalization for a family of six who inadvertently ingested Datura used as an ingredient in stew (Wikipedia). Devils trumpet grows naturally in disturbed areas such as eroded sites, old fields, vacant lots, overgrazed pastures and rangeland, roadsides and abandoned roadbeds, and fencerows (PIER). Dense infestations would have a minor effect on aesthetics. However, as the leaves produce an unpleasant odour when crushed and the fruit is armed with spines, some recreational activities may be affected. “Dense infestations occur in pastures and on river flats, producing a complete ground cover.” Likely to have a major impact on plants in the lower stratum. “Dense infestations occur in pastures and on river flats, producing a complete ground cover.” Likely to reduce available fodder for fauna species (Victorian Invasive Plants). All parts of the plant, particularly seeds, are toxic to livestock and humans. Rank smell and bitter taste usually deters stock from grazing plants (Weeds Australia). Dense infestations occur in pastures and on river flats, producing a complete ground cover. The plants die in the cooler autumn weather. However, dead plants bear capsules that may remain standing through winter into spring (Agriculture Victoria). Reports of human poisoning have occurred (CDC). All members of this genus contain narcotics and are very poisonous, even in small doses (PFAF).
Reference(s): 
10. Does the plant produce impenetrable thickets, blocking or slowing movement of animals, livestock, or humans?
Yes or No: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
Typically reaches a height of 0.6 to 1.5 metres (EOL). Erect annual or sometimes perennial herb, commonly 30 to 60 cm high. Unlikely to affect human access to recreational areas (Victorian Invasive Plants). An exhaustive Google/Google Scholar search did not reveal any evidence of this and the question defaults to a “no” answer at this time.
Reference(s): 
Reproductive Strategies
11. Does this species (or cultivar or variety) reproduce and spread vegetatively?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
In all localities in Croatia, D. inoxia occurs in a large number regenerating well from both the seed and the root (Current state of the distribution of the species Datura inoxia Miller (Solanaceae) in Croatia). When cultivated, the plant is usually grown from seed, but its perennial rhizomes can be kept from freezing and planted in the spring of the following year (TrekNature; Floridata).
Reference(s): 
12. If naturally detached fragments from this plant are capable of producing new plants, is this a common method of reproduction for the plant?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Spread by seed with some dispersal as cut root pieces (Weeds Australia). When cultivated, the plant is usually grown from seed, but its perennial rhizomes can be kept from freezing and planted in the spring of the following year (TrekNature; Floridata). In all localities in Croatia, D. inoxia occurs in a large number regenerating well from both the seed and the root (Current state of the distribution of the species Datura inoxia Miller (Solanaceae) in Croatia).
Reference(s): 
13. Does the species (or cultivar or variety) commonly produce viable seed?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Spread by seed with some dispersal as cut root pieces (Weeds Australia). When cultivated, the plant is usually grown from seed, but its perennial rhizomes can be kept from freezing and planted in the spring of the following year (TrekNature; Floridata). In all localities in Croatia, D. inoxia occurs in a large number regenerating well from both the seed and the root (Current state of the distribution of the species Datura inoxia Miller (Solanaceae) in Croatia).
Reference(s): 
14. Does this plant produce copious viable seeds each year (> 1000)?
Yes or No: 
Points: 
Confidence Level: 
Low
Answer / Justification: 
Seeds numerous (EOL). Thornapple plants produce a large amount of seed and seeds remain viable for more than 30 years, therefore, control is a long-term exercise (Victorian Invasive Plants). An exhaustive Google/Google Scholar search did not reveal any additional evidence regarding this and it defaults to remain unanswered at this time.
Reference(s): 
15. Is there significant germination (>25%) of seeds the next growing season, with no requirement of an infrequent environmental condition for seeds to germinate (i.e. fire) or long dormancy period?
Yes or No: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
Thornapple plants produce a large amount of seed and seeds remain viable for more than 30 years, therefore, control is a long-term exercise (Victorian Invasive Plants). Seeds of the thorn apple (recurved) require a period of 5-11 months after ripening before they germinate. Dormancy is influenced by a chemical inhibitor in the seedcoat, which must be leached out or broken down before germination occurs. Seeds are long lived with one experiment showing 91 per cent of seeds surviving 39 years after burial (Agriculture Victoria).
Reference(s): 
16. Does this plant produce viable seed within the first three years (for an herbaceous species) to five years (for a woody species) after germination?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Medium
Answer / Justification: 
Time to ultimate height only 1 year (RHS). Likely that seeds are produced within the first year, as it acts as an annual, but has a perennial rootstock (EOL).
Reference(s): 
17. Does this plant continuously produce seed for >3 months each year or does seed production occur more than once a year?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Fl. and fr. Jun-Sep. It flowers from early summer until late fall (EOL). Blooms March - October (Lady Bird Johnson Wildflower Center).
Reference(s): 
Dispersal
18. Are the plant’s propagules frequently dispersed long distance (>100 m) by mammals or birds or via domestic animals?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
The fruit is an egg-shaped spiny capsule, about 5 cm in diameter. It splits open when ripe, dispersing the seeds. Another means of dispersal is by the fruit spines getting caught in the fur of animals, who then carry the fruit far from the mother plant (EOL). The seeds are distributed by ants and some species of birds that are resistant to the chemicals they contain (PIER). Seed capsules spined (Lady Bird Johnson Wildflower Center).
Reference(s): 
19. Are the plant’s propagules frequently dispersed long distance (>100 m) by wind or water?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Medium
Answer / Justification: 
Both the seeds and capsules float on water, which provides an effective means of dispersal (Agriculture Victoria).
Reference(s): 
20. Are the plant’s propagules frequently dispersed via contaminated seed (agriculture or wildflower packets), equipment, vehicles, boats or clothing/shoes?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Listed as potential weed seed contaminant (ARS GRIN). The fruit is an egg-shaped spiny capsule, about 5 cm in diameter. It splits open when ripe, dispersing the seeds. Another means of dispersal is by the fruit spines getting caught in the fur of animals, who then carry the fruit far from the mother plant (EOL). Seed capsules spined (Lady Bird Johnson Wildflower Center). “Thornapple seeds are difficult to separate from seeds of grain sorghum…and contaminated samples are downgraded or rejected.” Produce rejected for sale (Victorian Invasive Plants). Most of the weed is spread through the contamination of agricultural seeds. Seeds are also dispersed via machinery, vehicles and mud. Pieces of root of the plant's perennial species are also dispersed when dragged by cultivation equipment (Agriculture Victoria).
Reference(s): 
Evaluation Notes

The scientific name is often cited as D. innoxia. When English botanist Philip Miller first described the species in 1768, he misspelled the Latin word innoxia (inoffensive) when naming it D. inoxia. The name Datura meteloides was for some time erroneously applied to some members of the species, but that name has now been abandoned.

The following webpages were consulted for this screen: Tropicos: http://www.tropicos.org/Name/29600687; USDA PLANTS: http://plants.usda.gov/core/profile?symbol=DAIN2; ARS GRIN: https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=13311; GBIF: http://www.gbif.org/species/2928745; CABI: http://www.cabi.org/isc/datasheet/113813; EOL: http://www.eol.org/pages/487967/overviewl; Calflora: http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=9854; LadyBird Johnson: http://www.wildflower.org/plants/result.php?id_plant=DAIN2; Jepson (congener): http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=22389; Dave’s Garden: http://davesgarden.com/guides/pf/go/355/; Wikipedia: https://en.wikipedia.org/wiki/Datura#Toxicity; CNPLX: http://www.cnplx.info/nplx/species?taxon=Datura+inoxia; PIER: http://www.hear.org/pier/species/datura_inoxia.htm; (congener) http://www.hear.org/pier/wra/australia/datsp-wra.htm; Efloras: http://efloras.org/florataxon.aspx?flora_id=12&taxon_id=200020518; Victoria weeds: http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/impact_thorn... Australian weeds committee: (congener) http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&state=&s=0&i... http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&state=&s=0&i... Agriculture Victoria: http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/weeds... CDC: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5233a2.htm; TrekNature: http://www.treknature.com/gallery/Asia/India/East/West_Bengal/Hooghly/ph... Floridata: http://www.floridata.com/Plants/Solanaceae/Datura%20inoxia%20var.%20quin... Learn 2 Grow: http://www.learn2grow.com/plants/datura/; PFAF: http://www.pfaf.org/user/Plant.aspx?LatinName=Datura+inoxia; UC IPM: http://www.ipm.ucdavis.edu/PMG/WEEDS/jimsonweed.html

Reviewed by Lynn Sweet.

Total PRE Score

  • < 13 : accept (low risk of invasiveness)
  • 13 - 15 : evaluate further
  • > 15 : reject (high risk of invasiveness)

PRE Score: 
21
Number of questions answered: 
19
Screener Confidence (%): 
82.1
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Evaluation visibility: 
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