Anne wondered about two-petalled spiderworts. After all, they are supposed to have three. Dayflowers seem to be minimalist spiderworts. I have no idea what the advantage of one less petal might be. Apparently these plants have found one. And each flower lasts but one day. Perhaps it's all about getting the job done with a minimum of effort. The flowers are a little less than an inch across. If you look really close, you can see a third pale petal below the filaments. This species grows in open spots in AL, AR, AZ, CO, DE, FL, GA, IA(T), IL, IN, KS, LA, MD, MI(X), MN, MO, MS, NC, NE, NJ(E), NM, NY, OK, PA(X), SD, TN, TX, VA, WI, WV, and WY. Monroe Co FL, 1/26/13.