“White-top sedge” can refer to either of two similar sedges that grow commonly in marshes, pine woods, and savannahs of the southeastern United States. They were once both referred to by the scientific name dichromena colorata, but now each is classified as a separate genus.
The one known most commonly as white-topped sedge now carries the scientific name of rhyncospora colorata. It is known by several other common names, including “narrowleaf sedge” and “starbrush white-top sedge”. It is an upright, tall perennial that is often mistaken for a lily. It prefers moist, marshy areas, and flowers from June to September. White-topped sedge grows throughout the states of Florida and Louisiana, and in the coastal regions of all Southern states as far north as Virginia. Its westward range extends into Oklahoma and through much of Texas, and it is reported to have spread to California. Its tiny flowers appear on spikelets that are surrounded by showy white bracts on top of triangular stems that grow up to about 2 ft. tall. The bracts are droopy and white, with green tips. The bracts look like leaves, but the plant’s true leaves grow at its base. White-topped sedge is vulnerable to frost, and grows in USDA Zones 8-11. It will occasionally grow in shallow water, and is highly deer-resistant. It is also tolerant of brackish water.
Giant white-topped sedge has the scientific name rhynchospora latifolia. It is also known as the “sandswamp white-top sedge”, “broadleaf whitetop sedge”, and “star-rush”. It has 3 to 10 bracts surrounding the flowers at the top, and needle-like leaves at its base. It flowers from May to September. Its slender stems grow up to 32 in. in height, and its needle-like leaves grow up to 16 in. in length and 1/4 in. wide. Like r. colorata, it spreads by rhizomes.
The name “rhyncospora” means “beaked seed”, and refers to the shape of the achenes that grow on both varieties of white-topped sedge. These are unusual among sedges in that their flowers attract insect pollinators. The two-sided achenes that appear on these sedges as fruit provide food to several birds, including cardinals, coots, painted buntings, and song sparrows. They also provide food to the larva of the Appalachian Brown butterfly, and to rabbits.
The white-topped sedges are good for water and bog gardens, and can be grown as annuals in colder regions. Their seeds are food for waterfowl, and they make good cut flowers. They live in sun or partial shade, and can sometimes be found in nurseries.