Rhynchospora Vahl. Beaksedge, Beakrush.

Contributed by Richard J. LeBlond, Bruce A. Sorrie, & Alan S. Weakley

Key to Rhynchospora

A genus of about 250 species, subcosmopolitan, but concentrated in tropical and warm temperate America. See Thomas (1984) for the reasons for the inclusion of Dichromena in Rhynchospora. Distributions given for tropical America are often based on Thomas (1992), with some modernizations and corrections.

Key advice:Members of the genus Rhynchospora -- mainly called beaksedges but also called beakrushes -- are mostly Coastal Plain in distribution and are important members of our longleaf pine savannas, flatwoods, streamheads, depression ponds, Carolina bays, and beaver ponds. They vary from small and wiry to large and coarse. Keys concentrate on features of the achenes (seeds) and the shape and arrangement of the flower clusters (spikelets). The seeds may or not have bristles at their base; bristle number, length, and toothing are critical characters. Size and shape of the seed beaks is also critical. The drawings in Godfrey & Wooten (1979) are extremely helpful. The genus now includes Dichromena, the white-topped sedges. Measurements and descriptions of the achene are of the achene body only, not including the tubercle (unless otherwise indicated). Occasional achenes of various bristle-bearing species, particularly those on immature specimens, will have filaments present alongside the bristles, both of which originate basally. These are not to be confused with the bristles, which are most often barbed, and can be distinguished by their weaker, twisting, and laterally flattened morphology (compared to the stiffer sometimes unilaterally curved but not flexuous or sinuate bristles that are often persistent).

Ref: Bridges & Orzell (2000); Bridges & Orzell (2023) In Weakley et al. (2023); Ciafré & Naczi (2022); Gale (1944); Goetghebeur In Kubitzki (1998b); Kral (1996); Kral (1999); Kral (2002e) In Flora of North America Editorial Committee (2002b); McMillan (2007); Naczi & Moyer (2017); Naczi, Knapp, & Moore (2010); Naczi, Knapp, & Thomas (2012); Sorrie, LeBlond, & Weakley (2018a) In Weakley et al. (2018b); Treher Eberly & Naczi (2023); Ungberg (2022) In Weakley et al. (2022); Ward (2012a). Show full citations.

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