Tansy ragwort, Heeswijk-Dinther, Netherlands

Introduced and invasive, named "Jacob's Herb" in dutch. This one spread likes wildfire, with a single adult plant capable of producing 75,000 to 200,000 seeds. This plant is poisonous to most mammals, capable of doing irreversible liver damage when consumed in too large quantities. The greatest threat is cattle eating it, affecting not just their selves, also the consumer of their milk.