cirsium arvense

[piranha]

canada thistle, invasive. bad naming, since it doesn't originate in canada, but in eurasia. it's a ruderal species, which means it is among the first plants to colonise disturbed land after fires, avalanches, or human actions such as construction, clear cutting, etc. typical for a ruderal species are fast-growing roots, massive seed production, and modest nutritional needs for seedlings. butterflies and gold finches go nuts for it (the former for the blooms, the latter for the seeds).

allegedly the roots and stalks are edible, but i've never tried.