Arum, an Unwelcome Guest

The non-native plant Italian arum (Arum italicum), is kind of like an unwelcome night-owl roommate who raids the fridge while everyone sleeps and co-opts shared spaces with their stuff. Literal turf wars can erupt! The pernicious invader has taken root in several locations within the Baltimore Woods corridor while the Friends and partners seek ways to remove it. The plant’s tendency to produce numerous tiny tubers makes that a challenge.

Italian arum is a nonnative perennial that was originally introduced as an ornamental plant. It has now naturalized in the Portland area. Due to it establishing in riparian areas and other habitats, its toxicity, and being very difficult to control once established, it is considered an invasive species in Portland. Animals and birds that eat the berries are probably the chief method of dispersal from the home landscape to natural areas. it may also be spread by improper disposal of the corms (tuber-like underground stems) from which it grows.

Since it may not be responsive to mechanical or chemical removal or even to burning, it is absolutely critical that we stop planting it. Once established though, the best method of removal is by digging. It is necessary to dig up the entire plant (including the bulbs and all the tubers) and bag and dispose of it as landfilled waste—not compost! It may take several years of repeated mechanical removal to eradicate arum from an area but the Friends are out to win this turf war!