This yellow wildflower is common from the Great Lakes westward. Yes, yellow in its most common form. But it also entertains us with yellow to almost brown forms. Some would even say purple if they include that form in the species. As we travel west, we always particularly enjoy wallflowers for their variation. There is so much yellow mustard. Also called western wallflower, but the sanddune name helps separate it from another very similar plant. This one occurs in AK, AR, AZ, CA, CO, IA, IN(T), IL, KS, MD, MI, MO, MT, NM, NV, OH, OK, OR, TN(E), TX, UT, VA, WA, WI, WV, WY, and YK. Clear Creek Co CO, 6/18/13.