Cow parsnip (Heracleum lanatum)

Cow parsnip photograph; © MN DNR, G. N. Rysgaard Cow parsnip photograph; © MN DNR, G. N. Rysgaard

Large coarse perennial grows 3-7' tall in moist, disturbed ground along streams and ditches. White flowers bloom in August and grow in ?umbels? or flat-topped clusters. Leaves are wooly underneath.