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Alien Plant Invader: Italian arum (Orange Candleflower)

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Italian arum, also known as lords-and-ladies or orange candleflower, is an invasive species in the Portland area.  It’s originally from Europe and is on the list of Early Detection Rapid Response plants.  These are invasive species that we need to get under control in Portland now, so they don’t become expensive, damaging infestations like ivy and blackberry.

When it’s not flowering, Italian arum can be mistaken for calla lily, but beware – this plant can quickly become a nightmare.

Why is Italian arum bad for Portland?  As the plants establish in residential yards and gardens, Italian arum can easily spread into Portland’s natural areas and parks.  This perennial plant spreads by seed and small underground corms (like bulbs).  The seeds and corms are spread by soil movement, gardeners, and running water. 

These plants, like other invasive species, threaten native plant diversity and damage wildlife habitat.  When invasive species take over our forests and stream banks, they cause increased erosion, slope instability, and water quality problems.  Human health is also a concern, as all parts of Italian arum are poisonous.  Contact with this plant can cause skin irritation; eating any part of the plant can be fatal.

 

Italian arum starts popping up in April and May.  First, you will see its dark green, waxy leaves with white veins. Then in late May, Italian arum produces white, hood-like flowers that look kind of like a calla lily. Finally the plant will produce tight clusters of berries which change from light green to orange-red.  Italian arum usually reaches a height of 12-18 inches.

Getting rid of Italian arum is a pain.  Even professional land managers struggle with it, which is why early control is very important.  Herbicides don’t work well and digging it up is a lot of work.  Manual removal is only recommended on small patches, because soil disturbance tends to increase the spread of the plant.  All plant parts and nearby soil should be placed in a bag and disposed of in the trash—not your yard waste bin or home compost.  Infested sites should be checked weekly to stay on top of any new sprouts. 

We encourage landowners to contact the City of Portland with any additional questions. Visit this page for more information about Italian arum. The National Park Service also has information available.

Invasive species affect us all. They damage our forests, streams and rivers, and property.  Nationwide, damages associated with invasive species are estimated to be $120 billion each year.  In Oregon, the damage invasive weeds cause and the cost of controlling them total about $125 million each year.  We know that it costs a lot less to control new invasive plants before they become infestations, so we need everyone’s help.  Find out more about the problems caused by invasive species and why Environmental Services works to stop their spread.

 

Catch up on previous Alien Plant Invader posts:

 

1 Comment

1

Judy Schmidt

October 3, 2014 at 10:16 PM

I just read the information you provided about Alien Plant Invader: Italian arum (Orange Candleflower). I just received 3 bulbs from Michigan Bulb to plant in my Central California garden. After reading this I am afraid to plant them! Are they as harmful in California as they are in Oregon? Thank you and I look forward to hearing back from you soon!

Judy

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Spam Prevention In the Pacific Northwest, what state is Portland in?