Distribution: Eastern U.S. to Mesomamerica, Caribbean

Commonly misidentification: Fimbristylis spadicea (L.) Vahl

Habitat:  Saline

Recognition:  Saltwater (often placed incorrectly under F. spadicea according to FNA).  Ligule absent. Achene 1.5-2 mm long. 

Fimbristylis cymosa also may occur on seaside beaches or dunes. The latter is likewise eligulate and likewise has blunt scales, but the spikelet is much smaller (2-3 mm vs. 5-20 mm), the achene is larger (1.5-2  mm vs. 1 mm long) and the inflorescence in F. castanea is usually compound (vs. usually simple in F. cymosa).

Also sometimes in brackish places, F. caroliniana has a ligule, unlike the other two species above.   In F. caroliniana the leaf blades are 2-5 mm wide. The stem is flattened and scabrous distally.

Photo: F. castanea