Starrush whitetop

Description

Rhynchospora colorata, also known as starrush whitetop, white star sedge and white-topped sedge, is a perennial sedge with white bracts, giving it the appearance of white petals with long, green points. It is native to southeastern North America, from Virginia west to New Mexico in the United States, and south into the Caribbean islands. Rhynchospora (beak-rush or beak-sedge) is a genus of about 400 species of sedges with a cosmopolitan distribution. The genus includes both annual and perennial species, mostly with erect 3-sided stems and 3-ranked leaves. The achenes bear a beak-like tubercule (hence the name “beak-rush”, although the plants are sedges, not rushes) and are sometimes subtended by bristles. Many of the species are similar in vegetative appearance, and mature fruits are needed to make a positive identification. The inflorescences (spikelets) are sometimes subtended by bracts which can be leaf-like or showy. Rhynchospora occurs on all continents except Antarctica, but is most diverse in the neotropics. It is most frequent in sunny habitats with wet, acidic soils. In marshes and savannas, Rhynchospora may be the dominant form of vegetation. Contemporary taxonomic treatments include Rhynchospora and the related genus Pleurostachys in the tribe Rhynchosporae, a well-supported clade within Cyperaceae. The most comprehensive monograph of the genus divides Rhynchospora into two subgenera and 29 sections. A recent molecular analysis identifies two primary clades within the genus, with well-supported subgroups that agree with several of the sections identified by Kükenthal. However, this molecular analysis also suggests that Pleurostachys is embedded within one of the primary clades of Rhynchospora and that several of the recognized sections are not monophyletic.