buttonweed, Diodia teres

Historically, buttonweed was a plant of open dryish areas. It's an annual, and would quickly appear in places of natural disturbance. Then we arrived and it probably went, "Wahoo!". It celebrates our modern disturbance any time we give it a chance. It now occurs in AL, AR, AZ, CA, CT, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, MI, MO, MS, NC, NJ, NM, NY, OH, OK, PA, RI, SC, TN, TX, VA, WI, and WV. Martin Co FL, 1/28/13. Madder family, Rubiaceae.