Commelina erecta, or Whitemouth dayflower, produces delicate blue flowers that quickly wither in the heat of the day. They have two blue petals and a small white one that appear as solitary blooms on the side or tips of stems. There is a complex of bright yellow stamens, including two at the base on the end of long, curving stalks. Leave are narrow and curve away from the stems, which tend to fall over.
References
Duncan, W. H., & Duncan, M. B. (1987). The Smithsonian guide to seaside plants of the Gulf and Atlantic coasts from Louisiana to Massachusetts, exclusive of lower peninsular Florida. Washington, D.C: Smithsonian Institution Press.
Richardson, A. (2013). Wildflowers and other plants of Texas beaches and islands. Austin, TX: University of Texas Press.