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PRE — Plant Risk Evaluator

Arum italicum -- California

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Evaluation Summary


Evaluation Date:  2021-04-15

Screener:  Jutta Burger
 
Plant:  Arum italicum
Common Name(s):
Italian arum, Italian lords and ladies, Large Cuckoo Pint, Orange Candleflower

State:  California

PRE Score:  19
Questions Answered:  20
Screener Confidence (%):  82

Executive Summary

Arum italicum is a tuber-forming perennial in the Araceae that has been used extensively in the horticultural industry. It has naturalized throughout the wetter regions of the western U.S. as well as locally in the eastern U.S., in Australia, New Zealand, portions of South America, and other regions. The plant is noted for its aggressive growth habit in gardens and riparian areas, its ability to cause contact dermatitis, and for being unpalatable to toxic for livestock. It reproduces both by seed that can be carried long distances and by lateral tubers, making it very difficult to control once established.

Climate Matching Map

https://weedmap.cal-ipc.org/climatematch/?areaType=states&areaList%5B0%5D=06&ma…
Attachment Size
climatematch-arum_italicum-california-20251031.pdf (1.14 MB) 1.14 MB

1. Question 1

Yes
1
Very High
Arum italicum is native to northern Africa, much of Europe, and parts of Russia and Turkey (USDA-GRIN). It has naturalized in California (Jepson Flora Project 2017), as well as across the western United States and Northeast (Swearingen and Bargeron 2015), Argentina (Forziano et al. 1991), Australia (Victorian Resources Online 2016), and New Zealand (New Zealand Plant Conservation Network 2017).
Victoria, Agriculture. 2016. “Invasiveness Assessment - Italian Lily (Arum Italicum) in Victoria”. http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/invasive_it….
Swearingen, J., and C. Bargeron. 2015. “Italian Arum: Invasive Plant Atlas of the United States”. http://www.invasiveplantatlas.org/subject.html?sub=13931.
Calflora. 2011. “Calflora: Arum Italicum”. https://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=730.
“Jepson EFlora: Arum Italicum”. 2017. http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=14303.
ARS, USDA. 2014. “USDA GRIN: Arum Italicum”. Germplasm Resources Information Network. https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?406582.
Forziano, M.J., J.V. Crisci, and G. Delucci. 1991. “Arum Italicum (Aralaceae) Especie Naturalizada de la Flora Argentina”. Kurziana 21: 237-41.

2. Question 2

Yes
2
Very High
Arum italicum is native to western Europe east to Iraq and Macaronesia (Boyce 1993; USDA GRIN). It is naturalized in several regions with climate similar to that in California, including in California (Calflora, accessed 2021). It is also naturalized in some areas with cooler, moister climates. Regions with overlapping climate and distribution include the Cape region of South Africa, portions of Australia and New Zealand, as well as the western U.S. and eastern U.S. mountain ranges (GBIF 2017).
Secretariat, GBIF. 2017. “GBIF Backbone Taxonomy: Arum Italicum”. Global Biodiversity Information Facility. doi:10.15468/39omei.
Calflora. 2011. “Calflora: Arum Italicum”. https://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=730.
Boyce, P. 1993. The Genus Arum. A Kew Magazine Monograph. London: HMSO Publications Centre.
ARS, USDA. 2014. “USDA GRIN: Arum Italicum”. Germplasm Resources Information Network. https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?406582.

3. Question 3

Yes
2
Very High
Arum italicum is noted as being invasive in several areas of the world. These include: Australia (Victorian Resources Online 2016), New Zealand (New Zealand Plant Conservation Network 2017), the Pacific Islands (Pacific Islands Ecosystems at Risk 2011), and Washington State (2010).
Victoria, Agriculture. 2016. “Invasiveness Assessment - Italian Lily (Arum Italicum) in Victoria”. http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/invasive_it….
“Arum Italicum (PIER Species Info)”. 2011. http://www.hear.org/pier/species/arum_italicum.htm.
“Arum Italicum - New Zealand Plant Conservation Network”. 2017. http://www.nzpcn.org.nz/flora_details.aspx?ID=3473.
“Washington State Noxious Weed List”. 2010. https://www.nwcb.wa.gov/printable-noxious-weed-list.

4. Question 4

Yes
3
Very High
Arum italicum is invasive in several regions with climate similar to that in California. Regions with overlapping climate and documentation of invasiveness include central Europe, portions of Australia (Australia's Virtual Herbarium) and New Zealand (New Zealand Plant Conservation Network 2017), as well as Washington State (Washington State Noxious Weed Board 2014). It is considered locally invasive in Oregon, New York, and Maryland where climate matches to a more limited degree (Swearingon and Bargeron 2015).
Swearingen, J., and C. Bargeron. 2015. “Italian Arum: Invasive Plant Atlas of the United States”. http://www.invasiveplantatlas.org/subject.html?sub=13931.
Victoria, Agriculture. 2016. “Invasiveness Assessment - Italian Lily (Arum Italicum) in Victoria”. http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/invasive_it….
“Arum Italicum - New Zealand Plant Conservation Network”. 2017. http://www.nzpcn.org.nz/flora_details.aspx?ID=3473.
Herbarium, Australia\textquoterights Virtual. 2016. “Weeds of Australia: Arum Italicum”. Queensland Government. https://keyserver.lucidcentral.org/weeds/data/media/Html/arum_italicum….
“Washington State Noxious Weed List”. 2010. https://www.nwcb.wa.gov/printable-noxious-weed-list.
Board, Washington State Noxious Weed Control. 2014. “Written Findings of the Washington State Noxious Weed Control Board: Arum Italicum.”
“Cal-IPC Global Map of Climate Areas Matching California”. 2016. info@cal-ipc.org.

5. Question 5

Yes
1
High
Arum maculatum is considered invasive in Chile (Randall 2017).
Randall, R. P. 2017. “A Global Compendium of Weeds. Third Edition”. Dept. of Agriculture and Food, Western Australia. https://www.researchgate.net/publication/313645439_A_Global_Compendium_….

6. Question 6

Yes
2
Medium
Arum italicum extends across three of the five global ecozones that match portions of California's climate (Australia's Virtual Herbarium; Forziano et al., 1991; NC State University, 2016; New Zealand Plant Conservation Network, 2017; Victorian Resources 2016; Washington State Noxious Weed Control Board). It does not appear to occur in either Temperate Desert or Subtropical Desert ecozones (GBIF 2017; California's Climate Matching map) .
Secretariat, GBIF. 2017. “GBIF Backbone Taxonomy: Arum Italicum”. Global Biodiversity Information Facility. doi:10.15468/39omei.
Forziano, M.J., J.V. Crisci, and G. Delucci. 1991. “Arum Italicum (Aralaceae) Especie Naturalizada de la Flora Argentina”. Kurziana 21: 237-41.
Victoria, Agriculture. 2016. “Invasiveness Assessment - Italian Lily (Arum Italicum) in Victoria”. http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/invasive_it….
Board, Washington State Noxious Weed Control. 2021. “Italian Arum: Arum Italicum Brochure”. https://www.nwcb.wa.gov/pdfs/ItalianArum_Brochure.pdf.
“Arum Italicum - New Zealand Plant Conservation Network”. 2017. http://www.nzpcn.org.nz/flora_details.aspx?ID=3473.
Extension, North Carolina State. 2016. “NC State Plant List - Arum Italicum”. https://plants.ces.ncsu.edu/plants/all/arum-italicum/.
Herbarium, Australia\textquoterights Virtual. 2016. “Weeds of Australia: Arum Italicum”. Queensland Government. https://keyserver.lucidcentral.org/weeds/data/media/Html/arum_italicum….
“Cal-IPC Global Map of Climate Areas Matching California”. 2016. info@cal-ipc.org.

7. Question 7

Yes
1
Medium
There is some evidence that Arum italicum can form monocultures that outcompete and overtop natives. In moist, coastal habitats in Washington State, monospecific stands of up to 7500 ft2 have been reported (Washington State Noxious Weed Control Board), though evidence from other areas is more limited.
Board, Washington State Noxious Weed Control. 2014. “Written Findings of the Washington State Noxious Weed Control Board: Arum Italicum.”

8. Question 8

No
0
High
There is no evidence that this species promotes fire or changes fire regimes. It grows primarily in moist climates. However, it does respond favorably to fire by resprouting vigorously (Victorian Resources Online 2016).
Victoria, Agriculture. 2016. “Invasiveness Assessment - Italian Lily (Arum Italicum) in Victoria”. http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/invasive_it….

9. Question 9

Yes
1
Very High
Arum italicum contains cyanogenic glucosides, saponins, and Calcium oxalate crystals, which can cause skin irritations, arrhythmia, and internal bleeding (University of California: Safe and Poisonous Garden Plants, Wink 2009). This species can poison and kill livestock as well, and has been listed as being a threat to livestock by several other weed assessments (Washington State Noxious Weed Board 2014).
Board, Washington State Noxious Weed Control. 2014. “Written Findings of the Washington State Noxious Weed Control Board: Arum Italicum.”
Wink, M. 2009. “Mode of Action and Toxicology of Plant Toxins and Poisonous Plants”. Mitt. Julius Kühn-Inst. 421: 93-112.
“Toxic Plants (by Scientific Name)”. 2012. http://ucanr.edu/sites/poisonous_safe_plants/Toxic_Plants_by_Scientific….

10. Question 10

No
0
High
The plant is low in stature, typically growing no more than 0.5m in height; foliage goes dormant / dies back in summer in all climates and in winter in colder regions (Missouri Botanical Garden 2016).
“MBOT Plant Finder - Arum Italicum”. 2016. http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.a….

11. Question 11

Yes
1
Very High
Arum italicum can spread by seed as well as vegetatively, by lateral tubers (Boyce 1993). Digging facilitates rapid propagation (Washington State Noxious Weed Control Board 2014, Victorian Resources 2016). Sprouts from tubers will flower in their second year (Mendez and Obeso 1993).
Mendez, M., and J. R. Obeso. 1993. “Size-Dependent Reproductive and Vegetative Allocation in Arum Italicum (Araceae)”. Canadian Journal of Botany 71: 309-14. doi:10.1139/b93-032.
Victoria, Agriculture. 2016. “Invasiveness Assessment - Italian Lily (Arum Italicum) in Victoria”. http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/invasive_it….
Board, Washington State Noxious Weed Control. 2014. “Written Findings of the Washington State Noxious Weed Control Board: Arum Italicum.”
Boyce, P. 1993. “The Genus Arum. A Kew Magazine Monograph”.

12. Question 12

Yes
1
Very High
Reports suggest that vegetative reproduction is common in the field (Washington State Noxious Weed Control Board 2014; Victorian Resources Online 2016). Research reports that there is a trade-off between sexual and vegetative reproduction in A. italicum (Mendez and Obeso 1993).
Mendez, M., and J. R. Obeso. 1993. “Size-Dependent Reproductive and Vegetative Allocation in Arum Italicum (Araceae)”. Canadian Journal of Botany 71: 309-14. doi:10.1139/b93-032.
Victoria, Agriculture. 2016. “Invasiveness Assessment - Italian Lily (Arum Italicum) in Victoria”. http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/invasive_it….
Board, Washington State Noxious Weed Control. 2014. “Written Findings of the Washington State Noxious Weed Control Board: Arum Italicum.”

13. Question 13

Yes
1
Very High
This species produces fleshy red orange/red fruits that contain viable seeds; plants can reproduce by seed as well as vegetatively (Albre and Gibernau 2008). Flowers are self-incompatible through dichogamy but plants are self-compatible (Mendez and Diaz 2001). Sexual reproduction results in lower resource allocation to vegetative reproduction (Mendez and Obeso 1993).
Mendez, M., and A. Diaz. 2001. “Flowering Dynamics in Arum Italicum (Araceae): Relative Role of Inflorescence Traits, Flowering Synchrony, and Pollination Context on Fruit Initiation”. American Journal of Botany 88: 1774-80. http://www.amjbot.org/content/88/10/1774.
Albre, Jerome, and Marc Gibernau. 2008. “Reproductive Biology of Arum Italicum (Araceae) in the South of France”. Botanical Journal of the Linnean Society 156: 43-49. doi:10.1111/j.1095-8339.2007.00737.x.
Mendez, M., and J. R. Obeso. 1993. “Size-Dependent Reproductive and Vegetative Allocation in Arum Italicum (Araceae)”. Canadian Journal of Botany 71: 309-14. doi:10.1139/b93-032.

14. Question 14

No
0
High
Seed production has been estimated at 83-355 seeds per inflorescence; per plant seed production is estimated at close to, but still less than 1000 seeds (Albre et al. 2003).
Albre, Jerome, and Marc Gibernau. 2008. “Reproductive Biology of Arum Italicum (Araceae) in the South of France”. Botanical Journal of the Linnean Society 156: 43-49. doi:10.1111/j.1095-8339.2007.00737.x.

15. Question 15

Yes
1
High
Seeds have little seed dormancy and germinate readily (Diaz et al. 2006).
Diaz, Anita, Melanie Aka Amoin, and Marc Gibernau. 2006. “The Effectiveness of Some Mechanisms of Reproductive Isolation in Arum Maculatum and A. Italicum (Araceae)”. Biological Journal of the Linnean Society 150: 323-28. https://www.researchgate.net/publication/227683831_The_effectiveness_of….

16. Question 16

No
0
High
Although vegetative propagules can become sexually reproductive, plants germinating from seed will typically take four years to flower (Albre and Gibernau 2008).
Albre, Jerome, and Marc Gibernau. 2008. “Reproductive Biology of Arum Italicum (Araceae) in the South of France”. Botanical Journal of the Linnean Society 156: 43-49. doi:10.1111/j.1095-8339.2007.00737.x.

17. Question 17

Yes
1
High
Arum italicum is listed as blooming over a four month period in California (Calflora; Jepson Flora Project).
Calflora. 2011. “Calflora: Arum Italicum”. https://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=730.
“Jepson EFlora: Arum Italicum”. 2017. http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=14303.

18. Question 18

Yes
1
Medium
Birds have been documented as the primary dispersers of A. maculatum (Snow and Snow 1988), so bird dispersal is also presumed to occur for A. italicum (Mendez 1997). Ants can also disperse seeds (Barroso 2013), though only birds will be likely to disperse seed long distances. Because Arum italicum is poisonous to many mammals and because fruits and seeds do not have any spines or barbs to adhere to fur, mammals are unlikely dispersers.
Borroso, A., F. Amor, X. Cerda, and R.R. Boulay. 2013. “Dispersal of Non-Myrmecochorous Plants by a ‘keystone Disperser’ in a Mediterranean Habitat Reveals Asymmetric Interdependence”. Insectes Sociaux 60: 75-86.
Mendez, M. 1997. “Sources of Variation in Seed Mass in Arum Italicum”. International Journal of Plant Sciences 158: 298-305.
Snow, B.K., and D.W. Snow. 1988. Birds and Berries. Scotland: T. & A.D. Poyser.

19. Question 19

No
0
Low
There is no evidence that fruits or seeds are dispersed by wind or water, likely because they are too heavy. Mendez (1997) reported an average seed weight of 33mg and 39mg for two populations of A. italicum. I was not able to find any reference for fruit buoyancy.
Mendez, M. 1997. “Sources of Variation in Seed Mass in Arum Italicum”. International Journal of Plant Sciences 158: 298-305.

20. Question 20

No
0
Medium
Arum italicum appears to have been introduced primarily as a garden ornamental. There are no records of it being a contaminant of seed, equipment etc. Fruits and seeds also do not carry barbs or hooks that could aid in transport. However, tuber fragments can readily generate new plants (Boyce 1993), so movement of soil from infested areas will move plants.
Boyce, P. 1993. “The Genus Arum. A Kew Magazine Monograph”.

Evaluation Notes

Websites accessed:

https://www.calflora.org/app/taxon?crn=730

Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals,  including the Consortium of California Herbaria.   [web application]. 2022. Berkeley, California:   The Calflora Database [a non-profit organization].   Available: https://www.calflora.org/ Accessed: 04/01/2021.

 

https://www.gbif.org/species/5330661

GBIF Secretariat (2021). GBIF Backbone Taxonomy:Arum italicum Mill. Checklist dataset https://doi.org/10.15468/39omei . Accessed via GBIF.org on 04/01/2021.

Added updated climate match link and map + corrected some reference script 11/1/2025. (J. Burger)

 

 

 

Total PRE Score

19
20
82

PRE Score Legend

The PRE Score is calculated by adding the point totals for each (answered) question.

< 13 : Low Potential Risk
13 - 15 : Moderate Potential Risk
> 15 : High Potential Risk

Questions Answered Legend

It is important to answer at least 16 questions to consider a PRE Score as "valid".

≥ 16 : Valid (80% or more questions answered)
≤ 15 : Invalid (not enough questions answered)

Evaluation Credits and Citation


Screener:  Jutta Burger

 

Below is a recommend citation when referencing this evaluation in other works:

Burger, Jutta. "Arum italicum -- California" Plant Risk Evaluator (PRE) published 2021-04-15 https://pretool.org/evaluations/1730

 


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Evaluation Reviewers

Scott Oneto reviewed on 2022-01-04
Elizabeth Brusati reviewed on 2021-10-18
Alex Simmons reviewed on 2021-10-18
reviewed on 2021-08-19

 

Associated Project

2021 Western IPM Grant Project

"Building Continuity Across State Invasive Plant Lists: Evaluating Invasive Risk of Horticultural Plants" is the title of the grant project funded by the Western Integrated Pest Management Center for the 2021 grant cycle. Project partners include California Invasive Plant Council, PlantRight, The University of Arizona, Western Invasives Species Network, and Washington Invasive Species Council. This project is one of three complimentary projects in two other region of the U.S. 


 

Associated Organizations, Agencies, and Institutions

California Invasive Plant Council (Cal-IPC)
PlantRight

 

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