Arum italicum (Italian Arum)—New WA State Noxious Weed

Arum italicum in May

I have Arum italicum (Italian arum) in my garden, and in fact, 4 years ago I posted an ode to its beauty and ease of care in the garden.  I will be digging it out this spring after learning that the plant is listed for 2015 on the Washington State Noxious Weed list.

I remember seeing it for the first time in at the Hulda Klager Lilac Gardens in Woodland, WA.  There it was used as a dramatic herbaceous foil to their fabulous April display of spring bulbs, and of course, lilacs.  I subsequently purchased it for my garden.  This was in the mid-90s, but the tuberous plant has proven to be too successful at naturalizing in the wild.

The cultivar ‘Marmoratum’ is better known than the straight species because it’s leaves have a striking white pattern.  My arum has plain green leaves.  Either way, I understand that once plants are established, they are difficult to eradicate.  Another key identifying feature is the late summer seed stalk with poisonous, tomato-red berries.

Ripening fruit

Since Arum italicum goes dormant in early summer, my first attempt to remove it will be well before that.  I will dig and bag the plants, getting as many of the tubers as I can and dispose of all the plant parts in the trash.  According to Dana Coggon, Kitsap County Noxious Weed Coordinator, the plant has shown up in commercially produced compost, another red flag that prompted the listing of this plant as Noxious Weed in WA State.

If I miss any tubers on the first go, I will know in the late fall when and if the leaves shoot up again in, which is their normal cycle.

Arum italicum forms large clumps in full or part shade.  Because of its summer dormancy, it survives well in areas with little summer water, another characteristic that makes it problematic when it escapes from gardens.

© Colleen Miko, 2015

About Colleen Miko

Colleen Miko is a certified professional horticulturist with 20 years experience in landscape design who has designed award winning gardens for the NW Flower & Garden Show as well as HGTV’s “Landscaper’s Challenge”. Colleen is freelance garden writer and speaker.
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