Beware! Giant Hogweed at Dry River Shelter #2

While hiking Isolation yesterday, we visited the Dry River Shelter #2 where I was horrified to see a patch of Giant Hogweed (Heracleum Mantegazzianum) growing less than ten feet from the shelter opening.

Giant Hogweed is a NASTY toxic plant - the sap causes huge blisters and permanent scarring and a tiny amount in the eyes can cause blindness.

https://en.m.wikipedia.org/wiki/Heracleum_mantegazzianum

Doug Cygan, Invasive Species Coordinator with the NH State Department of Agriculture says, “It’s by far the worst plant pest when it comes to human health.”

Thanks for pointing that out. How tall were the plants?

Is it possible it was cow parsnip, a very similar native plant (also somewhat nasty)?

Giant hogweed grows to 15 feet or so, cow parsnip is closer to 6 feet. This is a pretty good description of both. A good leaf picture can determine the difference as well.

https://www.youtube.com/watch?v=sysmrqw4sEo

If it's either one, it's best to stay away from it. If it is Giant Hogweed, the USFS office would appreciate a call I imagine.

That appears to be Cow Parsnip. There is also a large patch of Cow Parsnip growing in front of Rocky Branch shelter #2.

I made the same I.D. on a whack in NYS, cow parsnip, thinking it was Giant Hogweed.

Wow - they appear identical other than the size, are there other identifying traits to notice?

The yellow flower plant is actually wild parsnip. Very similar to the less common whitish flower cow parsnip. The wild parsnip version is what is dominating roadsides and open fields. It did not exist in my neck of the woods until about 6-8 years ago, but now is everywhere and spreading fast. Be very careful when weeding around this stuff, or you might get what is called weed wacker dermatitis from being sprayed with plant juice. Giant hogweed is very similar, though larger and far worse.

http://www.dec.ny.gov/animals/72766.html

http://www.dec.ny.gov/animals/39809.html

http://dnr.wi.gov/wnrmag/html/stories/1999/jun99/parsnip.htm

http://www.dot.state.mn.us/adopt/documents/wild-parsnips.pdf