Rhynchospora

Rhynchospora (beak-rush or beak-sedge) is a genus of about 400 species of sedges with a cosmopolitan distribution.[1][2][3][4][5][6][7][8][9][10] 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[1]
  • Rynchospora Vahl
  • Phaeocephalum Ehrh
  • Dichromena Michx.
  • Triodon Pers.
  • Spermodon P.Beauv. ex Lestib.
  • Zosterospermon P.Beauv. ex Lestib.
  • Pterotheca C.Presl
  • Calyptrostylis Nees
  • Cephaloschoenus Nees
  • Ceratoschoenus Nees
  • Diplochaete Nees
  • Echinoschoenus Nees & Meyen
  • Haloschoenus Nees
  • Haplostylis Nees
  • Mitrospora Nees
  • Morisia Nees
  • Psilocarya Torr.
  • Eriochaeta Torr. ex Steud.
  • Leptoschoenus Nees
  • Microchaeta Rchb.
  • Sphaeroschoenus Nees
  • Asteroschoenus Nees
  • Ephippiorhynchium Nees
  • Hygrocharis Nees
  • Pachymitra Nees
  • Ptilochaeta Nees
  • Astroschoenus Lindl.
  • Kleistrocalyx Steud.
  • Calyptrolepis Steud.
  • Cleistocalyx Steud.
  • Ptilosciadium Steud.
  • Trichochaeta Steud.
  • Pterochaete Arn. ex Boeckeler
  • Lonchostylis Torr.
  • Syntrinema H.Pfeiff.
  • Micropapyrus Suess.

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

Ecology

Rhynchospora occurs on all continents except Antarctica, but is most diverse in the neotropics.[11] It is most frequent in sunny habitats with wet, acidic soils.[12] In marshes and savannas, Rhynchospora may be the dominant form of vegetation.

Taxonomy

Contemporary taxonomic treatments include Rhynchospora and the related genus Pleurostachys in the tribe Rhynchosporae, a well-supported clade within Cyperaceae.[13] The most comprehensive monograph of the genus [14] divides Rhynchospora into two subgenera and 29 sections. A recent molecular analysis [15] 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.

Selected species
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References
  1. Kew World Checklist of Selected Plant Families
  2. Acevedo-Rodríguez, P. & Strong, M.T. (2005). Monocotyledons and Gymnosperms of Puerto Rico and the Virgin Islands. Contributions from the United States National Herbarium 52: 1-415.
  3. Strong, M.T. (2006). Taxonomy and distribution of Rhynchospora (Cyperaceae) in the Guianas, South America. Contributions from the United States National Herbarium 53: 1-225.
  4. Govaerts, R. & Simpson, D.A. (2007). World Checklist of Cyperaceae. Sedges: 1-765. The Board of Trustees of the Royal Botanic Gardens, Kew.
  5. Flora of China, Vol. 23 Page 253, 刺子莞属 ci zi guan shu, Rhynchospora Vahl, Enum. Pl. 2: 229. 1805.
  6. Flora of North America, Vol. 23 Page 200, Rhynchospora Vahl, Enum. Pl. 2: 229. 1805 (as Rynchospora)
  7. Gale, S. 1944. Rhynchospora sect. Eurhynchospora in Canada, the United States and the West Indies. Rhodora 46: 80–134, 159–197, 255–278.
  8. Kral, R. 1996. Supplemental notes on Rhynchospora crinipes and related species in sect. Fuscae (Cyperaceae). Sida 17: 385–411.
  9. Kükenthal, G. 1949–1951. Vorarbeiten zu einer Monographie der Rhynchosporoideae 18. Rhynchospora Vahl. Bot. Jahrb. Syst. 74: 375–509; 75: 90–115, 273–314, 451–497.
  10. Thomas, W. W. 1994. 1. Rhynchospora Vahl. 6: 404–422. In G. Davidse, M. Sousa Sánchez & A.O. Chater (eds.) Flora Mesoamericana. Universidad Nacional Autónoma de México, México, D. F.
  11. Thomas, W.W. 1992. A synopsis of Rhynchospora (Cyperaceae) in Mesoamerica. Brittonia 44:14–44.
  12. Kral, R. 2002. Rhynchospora. In: Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 15+ vols. New York and Oxford. Vol. 23 pp. 200-239.
  13. Muasya, A. M., J. Bruhl, D. A. Simpson, A. Culham and M. W. Chase. 2000. Suprageneric phylogeny of Cyperaceae: A combined analysis. pp. 593–601. In: K. Wilson and D. Morrison (eds.) Monocots: Systematics and Evolution. CSIRO: Melbourne.
  14. Kükenthal, G. 1949-1951. Vorarbeiten zu einer Monographie der Rhynchosporoideae. Rhynchospora. Bot. Jahrb. Syst. 74, 75
  15. Thomas W.W., A.C. Araujo, and M.V. Alves. 2009. A Preliminary Molecular Phylogeny of the Rhynchosporae (Cyperaceae). Botanical Review 75:22-29.
  16. Rhynchospora glomerata (L.) Vahl USDA Plants Profile. 23 Nov 2011
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