Rhynchospora

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.

Beak-sedge
Rhynchospora fascicularis
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Family: Cyperaceae
Genus: Rhynchospora
Vahl
Type species
Rhynchospora alba
(L.) Vahl.
Synonyms
  • Asteroschoenus Nees
  • Astroschoenus Lindl.
  • Calyptrolepis Steud.
  • Calyptrostylis Nees
  • Cephaloschoenus Nees
  • Ceratoschoenus Nees
  • Cleistocalyx Steud.
  • Dichroma Ham.
  • Dichromena Michx.
  • Diplochaete Nees
  • Echinoschoenus Nees & Meyen
  • Ephippiorhynchium Nees
  • Eriochaeta Torr. ex Steud.
  • Haloschoenus Nees
  • Haplostylis Nees
  • Hygrocharis Nees
  • Kleistrocalyx Steud.
  • Leptoschoenus Nees
  • Lonchostylis Torr.
  • Microchaeta Rchb.
  • Micropapyrus Suess.
  • Mitrospora Nees
  • Morisia Nees
  • Nemochloa Nees
  • Nomochloa Nees
  • Pachymitra Nees
  • Phaeocephalum Ehrh
  • Pleurostachys Brongn.
  • Psilocarya Torr.
  • Pterochaete Arn. ex Boeckeler
  • Pterotheca C.Presl
  • Ptilochaeta Nees
  • Ptilosciadium Steud.
  • Spermodon P.Beauv. ex Lestib.
  • Sphaeroschoenus Nees
  • Syntrinema H.Pfeiff.
  • Trichochaeta Steud.
  • Triodon Pers.
  • Zosterospermon P.Beauv. ex Lestib.

The inflorescences (spikelets) are sometimes subtended by bracts which can be leaf-like or showy.

Members of this genus have holocentric chromosomes, which is rare in eukaryotes, and have become a model for the study of chromosome evolution. The genomes of Rhynchospora pubera, R. breviuscula, and R. tenuis have been published in 2022.

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