Red berry-like fruit on short green stems
Photo: Jennifer Mo

Arum italicum Risk Assessment

Synonyms: Arum italicum Mill., Arum italicum subsp. italicum

Common names: Italian Arum, Italian lords and ladies, large cuckoo pint, orange candleflower

Arum italicum -- California

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Created by: Jutta Burger
Created on: Thursday, Apr 15th, 2021
Evaluation 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.
General Evaluation Information
Date of Evaluation: 
April 15, 2021
Evaluation Time (hrs): 
5 Hours
Evaluation Status: 
Completed
Plant Information
Plant: 
Arum italicum
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: 
California
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.
PRE Climate Map (external link)
Climate Matching Maps PDF: 
AttachmentSize
PDF icon California_climate match.pdf505.76 KB
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: 
Very High
Answer / Justification: 
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).
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: 
Very High
Answer / Justification: 
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).
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: 
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).
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: 
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).
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: 
High
Answer / Justification: 
Arum maculatum is considered invasive in Chile (Randall 2017).
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: 
Medium
Answer / Justification: 
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) .
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: 
Medium
Answer / Justification: 
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.
Reference(s): 
8. Is the plant noted as promoting fire and/or changing fire regimes?
Yes or No: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
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).
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: 
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).
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: 
High
Answer / Justification: 
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).
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: 
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).
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: 
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).
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: 
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).
Reference(s): 
14. Does this plant produce copious viable seeds each year (> 1000)?
Yes or No: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
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).
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: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Seeds have little seed dormancy and germinate readily (Diaz et al. 2006).
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: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
Although vegetative propagules can become sexually reproductive, plants germinating from seed will typically take four years to flower (Albre and Gibernau 2008).
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: 
Arum italicum is listed as blooming over a four month period in California (Calflora; Jepson Flora Project).
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: 
Medium
Answer / Justification: 
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.
Reference(s): 
19. Are the plant’s propagules frequently dispersed long distance (>100 m) by wind or water?
Yes or No: 
No
Points: 
0
Confidence Level: 
Low
Answer / Justification: 
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.
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: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
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.
Reference(s): 
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.

 

 

Total PRE Score

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

PRE Score: 
19
Number of questions answered: 
20
Screener Confidence (%): 
82.0
PRE Content Access and Privacy
Organization: 
California Invasive Plant Council (Cal-IPC)
2021 Western IPM Grant Project
PlantRight
Evaluation visibility: 
Private - accessible only to organization members

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