Scotch Thistle (Onopordum acanthium)

Close-up of mature flower plant as seen May through July.  Biennial in northern states, but often acts as a cool-season annual in Oklahoma.  Stems with broad, spiny wings that grow to eight feet tall.  Plant exist as rosette in fall and winter with large, up to two feet long and one foot wide, coarsely lobed, sparsely to densely cotton-like hair on both surfaces.