Italian arum: Beautiful, poisonous and invasive

Italian arum is a deceptively attractive invasive imposter. I fell for her ruse. The bright orange berries brought color to an otherwise nondescript area of the yard, so I let it grow. Now I wish it had never found my address as it has found its way into most of my garden beds, even in the lawn.

Because it is so invasive and poisonous to humans and animals, the Washington State Department of Agriculture classifies it as a Class C noxious weed. Class C noxious weeds are described as “already widespread in Washington. In some cases, counties may require property owners to control Class C weeds, but more often counties simply try to educate residents about why controlling them is a good idea.”

Like many invasive plants, Italian arum likely escaped from someone’s garden. Originally planted as an ornamental groundcover, it certainly does cover ground. The first documented site in Washington state was on San Juan Island in 2002.

Not only is this plant invasive, but it also contains calcium oxalates, poisonous to humans and animals. According to the North Carolina Extension Gardener Toolbox, calcium oxalates, if ingested “will cause throat and tongue swelling that will result in difficulty breathing or possible death.” Simple skin contact can cause mild to severe irritation. Always protect your skin when attempting to remove Italian arum.

Unfortunately, the plant tolerates most soil types, is drought tolerant once established and thrives in partial shade to full sun. Like many undesired plants, it has more than one reproductive strategy. It grows from both tubers and berries, reaching 12-18 inches tall. The arrow-shaped leaves appear in early autumn, with hood-like flowers blooming in April and May: their acrid odor attracts flies as pollinators. When the foliage withers, stalks emerge, eventually covered in clusters of berries. The plump berries are initially green, changing to a vivid orange-red. This dramatic show continues through August, giving birds plenty of time to snack on the berries and then deposit the seeds around your yard and beyond.

Once established, Italian arum is maddeningly difficult to get rid of. According to the North Carolina Extension Gardener Plant Toolbox, “There are no effective ways to control the plant and it is unresponsive to herbicides. Manual removal is difficult. If removed, all parts of the plant should be placed in the trash and not your compost bin.”

An Oregon State University Extension’s Ask An Expert webpage offers this: “Some suggest success by pouring boiling water on the plant’s roots. If using vinegar, a 20% vinegar solution is best. This type of vinegar, sometimes called horticultural vinegar, can be found at garden centers, farm stores or online. Wear gloves and protective clothing to protect your skin from possible irritation. Follow–up work will be required to control any plants that develop from missed plant parts.”

Don’t let the pretty leaves or colorful berries fool you into letting Italian arum take root in your yard. And tell your friends and neighbors not to allow Italian arum to charm its way into their gardens. Read the full article at: https://www.skagitmg.org/italian-arum/