http://the-biologist-is-in.blogspot.com/search/label/rocky slope). It is the very pretty, but also deadly, Aconitum delphiniifolium (Northern Monkshood). The plant survives for several years, spreading slowly by producing daughter tubers.
The toxins produced by plants in this genus (aconitine, mesaconitine, hypaconitine, etc.) bind to the voltage-sensitive sodium channels of nerve cell axons. Upon binding, the toxin forces the channels open and over-stimulate nerve signals until the cells can't respond any further. The cells then fail to send the signals necessary to maintain breathing or the hear-beat and death soon follows without aggressive treatment. At this stage, you will need cardiopulmonary bypass in order to have a good chance of surviving. All the while, you will be hallucinating madly and so will be unable to seek or assist in treatment.
Seriously, don't eat this plant. That said, it is quite pretty.