Land Plants - invasive

Italian Arum (Arum italicum) on Apr 16, 2008

Originally reported as Giant Hogweed (Heracleum mantegazzianum)

Submitter does not have a specimen

Description of specimen

The plant had just emerged but I think it is giant hogweed. Hogweed has grown (and been sprayed) in this same area in previous years. I will keep an eye on the plant and confirm that it is hogweed once it gets larger.


Thanks. When you think it is big enough to identify, please post a photo. You can hold on to this email and use the link to view the Hotline Report and add an image.

John Kin
April 16, 2008, 6:34 a.m.

I've added three pictures. "Giant Hogweed" is the plant I suspected in the location behind the condos just south of the Tigard Library. I'm pretty sure it is Hogweed and now there are 6 or 7 plants. "Giant Hogweed Downstream" is more hogweed located several hundred yards downstream near an old washout out bridge. I suspect, if I searched deeper in the woods, I'd find even more. "Unknown Invasive" is a large triangular leaf that is popping out at several locations along the trail beside Fanno Creek. This picture is taken behind the apartment complex downstream from the condos south of the library but there's more along the trail. I could probably spray if I knew the proper herbicide but I'd rather leave the hogweed to the experts.

April 20, 2008, 8:34 a.m.

Jeff - here is a response to your submission:

Your first 2 photos do look like giant hogweed, but not 100% sure without closer-up photos, or until the plant becomes larger.

Your last photo looks very much like Italian arum/Lords-and-ladies (Arum italicum) which is being reported from several sites in the Portland Metro area.

Thanks for your submission! mt

Mandy Tu
April 21, 2008, 7:22 a.m.