whorled milkweed, Asclepias verticillata

Old fields, new plants. Old fields were a little bit of an old thing. These days, thanks to all those chemicals, fields are not so often abandoned. No more slash, burn, and move on. But while agriculture has changed, people still find ways to screw up the soil. And where we do that, whorled milkweed might show up to help repair our damage. Originally a prairie species, it's quite contented to expand its range thanks to human activities. It now grows in AL, AR, AZ, CT, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA(T), MD, MI, MN, MO, MS, MT, NC, ND, NE, NJ, NM, NY, OH, OK, PA, RI(S), SC, SD, TN, TX, VA, VT, WI, WV, WY, MB, ON, and SK(E).