Kosteletzkya pentacarpos, Salt Marsh Mallow -  This full sun perennial grows typically to 4 to 6 feet in height, occasionally up to 10 feet, at maturity, which it reaches in about 5 years, and as much as 4ft across. Once it reaches this height, its life is nearing its end, as it only lives about 5 years. Easily grown from seed, saltmarsh mallow has a lengthy and striking bloom period, beginning as early as May and continuing into October. The showy flowers are reminiscent of Hibiscus flowers and range from a deep pink to a lightly pink hued white.  Prefers sand, but will tolerate clay. Moderately salt tolerant, though does best with high acidity. The plant grows in brackish, swampy conditions, shallow standing water, or regular garden soil; it is not tolerant of drought.
 
Native in the tidewater areas of the Coastal Plain and barrier island . Click to see its range in North Carolina
 
More info here