Courtesy of Eleanor Dietrich
Saltmarsh mallow
This plant (Kosteletzkya virginica or pentacarpos) is in the Mallow family, which also includes Hibiscus, so you will see some similarity between the flowers.
This plant may be found along the edges of fresh and saltwater marshes and grows throughout most of Florida.
The plant can reach heights of up to eight feet.
The attractive large (2 to 3 inches wide) pink flowers just open for a day.
You can see them blooming now at the end of Sand Beach Road in the Apalachicola River Wildlife and Environmental Area (ARWEA) off of SR 65 in Franklin County.