Why don't you just dig it up, you have got to consume not so small of a portion of roots to kill someone, to commit suicide they are to be eaten raw, and I am sure the toxins are only in the plant and not seeping out into the ground like it is at Dow Chemical. The tomato is poisonous as well. Two feet is a long way for a toxin that is relatively weak if you put it in prospective, and it does not broadcast its toxins, I am sure it is broken down quickly by UVA radiation very quickly, what about tobacco it is extremely poisonous as well.

Thank you for the ID! I'll keep that in mind and not walk through there again. :) I didn't smell anything bad around the plant (the breeze carried a sweet floral smell actually). I guess the bad odor would be from the sap/broken plant matter? Hm, interesting that a lot of the flora in the local park gets mowed down but they've left the entire hoard of these poisonous ones.

Yeah, while I'm up for composting meat and such that you're "not supposed" to compost I think I'd shy away from something like this... UNLESS I was doing something like Humanure where the pile was going to sit for 3 years... If there wasn't a tremendous amount of the stuff I might put the poison hemlock down on the ground, put some greens over it, then some cardboard and maybe a metal pipe (to mark the divide) and build a pile over that. When the compost above was done I'd dig only to the pipe, then build another pile. I'd keep doing that for maybe a couple years by which point the stuff underneith would be effectively gone... Pull the pipe and compost above normally. But composting poison, not sure I'd ever feel real good about that. Not that I'd be worried it'd get into my food but nervous I'd have a reaction to it while handling the compost...

Diane, the toxins are to ward off herbivores, not other plants and therefore are not released into the soil as allelopathic chemicals are. The toxins degrade readily and are unlikely to be taken up by other plants in any case. Most human poisoning occurs when people mistake the roots for parsnips or the tops for anise (the latter error is unfathomable to me as the foliage has a fairly strong odor - I have never grown parsnips or troubled myself to dig up any poison hemlock around here so I can't evaluate the odds on the former error). Ryan