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Rhynchospora
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| Beak-sedge | |
|---|---|
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| Rhynchospora fascicularis | |
Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Poales |
| Family: | Cyperaceae |
| Genus: | Rhynchospora Vahl |
| Type species | |
| Rhynchospora alba (L.) Vahl.
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| Synonyms[1] | |
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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.[1] [2]
The inflorescences (spikelets) are sometimes subtended by bracts which can be leaf-like or showy.[3][4]
Members of this genus have holocentric chromosomes and have become a model for the study of chromosome evolution and meiotic recombination in holocentric plants.[5] The genomes of Rhynchospora pubera, R. breviuscula, and R. tenuis have been published in 2022.[6]
Ecology
[edit]Rhynchospora occurs on all continents except Antarctica, but is most diverse in the neotropics.[7] It is most frequent in sunny habitats with wet, acidic soils.[8] In marshes and savannas, Rhynchospora may be the dominant form of vegetation.
Evolution
[edit]Chromosome evolution models point to polyploidy as the major driver of chromosome evolution in Rhynchospora (which is characterized as having holocentric chromosomes), followed by dysploidy[9]. Lineages that stayed in wet high acidity environments seemingly preserved low chromosome numbers and a high long terminal repeat retrotransposons (LTR-RTs) and DNA transposons content. However lineages (like those in North America) that rapidly diversified into less rainy regions underwent multiple fission events accompanied by a quick loss of LTR-RTs due to holokinetic drive and environmental constraints.[10]
A time-calibrated phylogenetic analysis of 115 taxa within the tribe, together with 11 outgroup taxa, estimated the mean crown-group age of the tribe at approximately 43.2 million years[11]. Ancestral state reconstruction using stochastic character mapping inferred that the most recent common ancestor (MRCA) occupied open (savanna) habitats. This habitat type accounted for 77% of the total reconstructed branch lengths across the phylogeny. Despite this predominance, an average of 22 independent transitions from open habitats to forest understory or forest-edge environments were inferred among descendant lineages. The ancestral soil association was reconstructed as seasonally wet savanna soils. Occurrence in dry, well-drained soils was reconstructed along 4% of the total branch lengths, with an estimated mean of 11.2 independent transitions to this condition. An average of 3.7 transitions were inferred to habitats characterized by standing or flowing water. Changes in inflorescence traits were also reconstructed. An average of 5.9 transitions from nondescript brown or green inflorescences associated with wind pollination to white spikelets and/or bracts associated with insect pollination were inferred. These transitions were not correlated with shifts to forest habitats. Taxa exhibiting C4 photosynthetic anatomy formed a distinct clade that diverged from a sister clade comprising taxa with C3 photosynthetic anatomy approximately 26 million years ago, earlier than previously estimated.
Taxonomy
[edit]Contemporary taxonomic treatments include Rhynchospora and the related genus Pleurostachys in the tribe Rhynchosporae, a well-supported clade within Cyperaceae.[12] The most comprehensive monograph of the genus [13] divides Rhynchospora into two subgenera and 29 sections. A recent molecular analysis [14] 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.[14]
- Selected species
- [1]
- Rhynchospora alba - White beak-sedge. Europe, North America
- Rhynchospora caduca - Southeast North America
- Rhynchospora californica - California beaked-rush, occurring in Marin and Sonoma County, California
- Rhynchospora capillacea - Slender beakrush. Eastern North America
- Rhynchospora capitellata - Brownish beak-sedge
- Rhynchospora colorata - White star sedge. Southeast North America.
- Rhynchospora fusca - Brown beak-sedge. Europe.
- Rhynchospora glomerata - Clustered beak-sedge. North America.[15]
- Rhynchospora inexpansa - Southeastern North America and West Indies
- Rhynchospora knieskernii - Knieskern's beak-sedge.
- Rhynchospora longisetis
- Rhynchospora macrostachya - Tall horned beaksedge. Eastern North America.
- Rhynchospora megalocarpa - Southeastern United States
- Rhynchospora megaplumosa - Florida
- Rhynchospora nervosa - Tropical New World.
- Rhynchospora rariflora - Southeastern North America, West Indies, Central America
- Rhynchospora scirpoides - North America
- Rhynchospora waspamensis - New World.
References
[edit]- ^ a b c "Rhynchospora Vahl | Plants of the World Online | Kew Science". Plants of the World Online. Retrieved 11 February 2024.
- ^ Govaerts, R. & Simpson, D.A. (2007). World Checklist of Cyperaceae. Sedges: 1-765. The Board of Trustees of the Royal Botanic Gardens, Kew.
- ^ Flora of China, Vol. 23 Page 253, 刺子莞属 ci zi guan shu, Rhynchospora Vahl, Enum. Pl. 2: 229. 1805.
- ^ Flora of North America, Vol. 23 Page 200, Rhynchospora Vahl, Enum. Pl. 2: 229. 1805 (as Rynchospora)
- ^ Castellani, Marco; Zhang, Meng; Thangavel, Gokilavani; Mata-Sucre, Yennifer; Lux, Thomas; Campoy, José A.; Marek, Magdalena; Huettel, Bruno; Sun, Hequan; Mayer, Klaus F. X.; Schneeberger, Korbinian; Marques, André (March 2024). "Meiotic recombination dynamics in plants with repeat-based holocentromeres shed light on the primary drivers of crossover patterning". Nature Plants. 10 (3): 423–438. Bibcode:2024NatPl..10..423C. doi:10.1038/s41477-024-01625-y. ISSN 2055-0278. PMC 10954556. PMID 38337039.
- ^ Hofstatter, Paulo G.; Thangavel, Gokilavani; Lux, Thomas; Neumann, Pavel; Vondrak, Tihana; Novak, Petr; Zhang, Meng; Costa, Lucas; Castellani, Marco; Scott, Alison; Toegelová, Helena; Fuchs, Joerg; Mata-Sucre, Yennifer; Dias, Yhanndra; Vanzela, André L.L. (2022). "Repeat-based holocentromeres influence genome architecture and karyotype evolution". Cell. 185 (17): 3153–3168.e18. doi:10.1016/j.cell.2022.06.045. ISSN 0092-8674. PMID 35926507.
- ^ Thomas, W.W. 1992. A synopsis of Rhynchospora (Cyperaceae) in Mesoamerica. Brittonia 44:14–44.
- ^ 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.
- ^ Burchardt, P., Buddenhagen, C. E., Gaeta, M. L., Souza, M. D., Marques, A., Vanzela, A. L. L. (2020). "Holocentric Karyotype Evolution in Rhynchospora Is Marked by Intense Numerical, Structural, and Genome Size Changes". Frontiers in Plant Science. 11. Frontiers Media S.A. doi:10.3389/fpls.2020.536507.
- ^ Costa, L., Castro, N., Buddenhagen, C. E., Marques, A., Pedrosa-Harand, A., Souza, G. (18 December 2024). "Repeat competition and ecological shifts drive the evolution of the mobilome in Rhynchospora Vahl. (Cyperaceae), the holocentric beaksedges". Annals of Botany mcae220. doi:10.1093/aob/mcae220. ISSN 1095-8290 0305-7364, 1095-8290. Retrieved 22 January 2025.
{{cite journal}}: Check|issn=value (help) - ^ Buddenhagen, C. E. (2016), A view of Rhynchosporeae (Cyperaceae) diversification before and after the application of anchored phylogenomics across the angiosperms., Florida State University
- ^ 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.
- ^ Kükenthal, G. 1949-1951. Vorarbeiten zu einer Monographie der Rhynchosporoideae. Rhynchospora. Bot. Jahrb. Syst. 74, 75
- ^ a b Thomas W.W., A.C. Araujo, and M.V. Alves. 2009. A Preliminary Molecular Phylogeny of the Rhynchosporae (Cyperaceae). Botanical Review 75:22-29.
- ^ Rhynchospora glomerata (L.) Vahl USDA Plants Profile. 23 Nov 2011
External links
[edit]Other sources
[edit]- 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.
- Gale, S. 1944. Rhynchospora sect. Eurhynchospora in Canada, the United States and the West Indies. Rhodora 46: 80–134, 159–197, 255–278.
- Kral, R. 1996. Supplemental notes on Rhynchospora crinipes and related species in sect. Fuscae (Cyperaceae). Sida 17: 385–411.
- 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.
- 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.
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