==Description==
==Description==
”Cyperus odoratus” is an [[Annual plant|annual]] [[wikt:sedge|sedge]] approaching half a meter in height on average but known to grow much taller. It usually has some long, thin leaves around the base of the plant. The [[inflorescence]] is made up of one to several cylindrical [[Raceme#Spike|spikes]], each resembling a bottle brush. There are 5 to 8 leaf-like [[bract]]s at the base of the inflorescence. Each of the spikes bears a large number of flat, oval-shaped [[spikelet]]s. Each spikelet is usually light brown to reddish-brown and has a few to over 20 flowers. Each flower is covered by a tough, flat scale (a kind of bract) with a visible midvein. The fruit is a flat [[achene]] less than two millimeters long.{{r|ucjeps|FNA}}
”Cyperus odoratus” is an [[Annual plant|annual]] [[wikt:sedge|sedge]] approaching half a meter in height on average but known to grow much taller. It usually has some long, thin leaves around the base of the plant. The [[inflorescence]] is made up of one to several cylindrical [[Raceme#Spike|spikes]], each resembling a bottle brush. There are 5 to 8 leaf-like [[bract]]s at the base of the inflorescence. Each of the spikes bears a large number of flat, oval-shaped [[spikelet]]s. Each spikelet is usually light brown to reddish-brown and has a few to over 20 flowers. Each flower is covered by a tough, flat scale (a kind of bract) with a visible midvein. The fruit is a flat [[achene]] less than two millimeters long.{{r|ucjeps|FNA}}
”Cyperus odoratus” is similar to ”[[Cyperus engelmannii]]”. The floral scales of ”Cyperus odoratus” are overlapping. In contrast, the mature floral scales of ”Cyperus engelmannii” do not overlap, that is, the tip of each scale does not reach the base of the next scale on the same side of the spikelet. The mature achenes of ”Cyperus odoratus” are slightly ellipsoid, while those of ”Cyperus engelmannii” are narrow with linear (parallel) edges.{{r|FSUS}}{{sfnp|Standley|2025}} The widths of fully developed achenes are 0.5–0.7 mm and 0.3–0.4 mm, respectively.{{sfnp|Naczi|2017|page=4}}
”Cyperus odoratus” is similar to ”[[Cyperus engelmannii]]”. The floral scales of ”Cyperus odoratus” are overlapping. In contrast, the mature floral scales of ”Cyperus engelmannii” do not overlap, that is, the tip of each scale does not reach the base of the next scale on the same side of the spikelet. The mature achenes of ”Cyperus odoratus” are slightly ellipsoid, while those of ”Cyperus engelmannii” are narrow with linear (parallel) edges.{{r|FSUS}}{{sfnp|Standley|2025}} The widths of fully developed achenes are 0.5–0.7 mm and 0.3–0.4 mm, respectively.{{sfnp|Naczi|2017|page=4}}
”Cyperus odoratus” and ”Cyperus engelmannii” are the only two ”Cyperus” species in [[temperate]] North America with spikelets that eventually break into one-seeded segments.{{sfnp|Tucker|Gandhi|2019}} At maturity, each spikelet breaks into segments each consisting of a scale and an achene held together by a portion of the floral axis.{{r|FNA}}
”Cyperus odoratus” and ”Cyperus engelmannii” are the only two ”Cyperus” species in [[temperate]] North America with spikelets that eventually break into one-seeded segments.{{sfnp|Tucker|Gandhi|2019}} At maturity, each spikelet breaks into segments each consisting of a scale and an achene held together by a portion of the floral axis.{{r|FNA}}
Species of plant
| Fragrant flatsedge | |
|---|---|
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Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Poales |
| Family: | Cyperaceae |
| Genus: | Cyperus |
| Species: |
C. odoratus |
| Binomial name | |
| Cyperus odoratus | |
| Synonyms[4][5][6] | |
C. o. subsp. transcaucasicus
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Cyperus odoratus is a species of flowering plant in the sedge family Cyperaceae. It is known by the common names fragrant flatsedge and rusty flatsedge. It has a pantropical distribution that extends into the temperate regions of North and South America. The species is quite variable and may in fact be more than one species included under a single name.
Cyperus odoratus sensu lato is an annual sedge approaching half a meter in height on average but known to grow much taller. It usually has some long, thin leaves around the base of the plant. The inflorescence is made up of one to several cylindrical spikes, each resembling a bottle brush. There are 5 to 8 leaf-like bracts at the base of the inflorescence. Each of the spikes bears a large number of flat, oval-shaped spikelets. Each spikelet is usually light brown to reddish-brown and has a few to over 20 flowers. Each flower is covered by a tough, flat scale (a kind of bract) with a visible midvein. The fruit is a flat achene less than two millimeters long.[7][8]
Cyperus odoratus sensu stricto is similar to Cyperus engelmannii. The floral scales of Cyperus odoratus are overlapping. In contrast, the mature floral scales of Cyperus engelmannii do not overlap, that is, the tip of each scale does not reach the base of the next scale on the same side of the spikelet. The mature achenes of Cyperus odoratus are slightly ellipsoid, while those of Cyperus engelmannii are narrow with linear (parallel) edges.[9][10] The widths of fully developed achenes are 0.5–0.7 mm and 0.3–0.4 mm, respectively.
Cyperus odoratus and Cyperus engelmannii are the only two Cyperus species in temperate North America with spikelets that eventually break into one-seeded segments.[12] At maturity, each spikelet breaks into segments each consisting of a scale and an achene held together by a portion of the floral axis.[8]
Cyperus odoratus was first described by the Swedish botanist Carl Linnaeus in 1753.[3] Linnaeus based his diagnosis on a specimen collected along a riverbank in North America (“habitat in America ad fluviorum ripas”).
As of October 2025[update], the following infraspecific names are accepted by both Plants of the World Online and World Flora Online:[4][14]
- Cyperus odoratus subsp. odoratus
- Cyperus odoratus subsp. transcaucasicus (Kük.) Kukkonen
The typical subspecies Cyperus odoratus subsp. odoratus has dozens of synonyms.[5] Cyperus odoratus var. engelmannii (Steud.) R.Carter, S.D.Jones & Wipff is a homotypic synonym of Cyperus engelmannii Steud.[15]
Cyperus odoratus is a member of Cyperus subgen. Diclidium (Schrad. ex Nees) C.B.Clarke.[12] It is one of two species in subgenus Diclidium whose range extends into temperate North America (the other species being Cyperus engelmannii).
Distribution and habitat
[edit]
Cyperus odoratus sensu lato is found in much of the tropical and warm temperate world, including South, Central, and North America, Southeast Asia, some Pacific Islands, Australia, New Guinea, Madagascar, and central Africa.[4][8][16] It is a plant of wet, muddy areas, including disturbed and altered sites. Cyperus odoratus subsp. transcaucasicus is native to Iran, Iraq, and the South Caucasus.[6]
- ^ Bárrios, S.; Copeland, A. (2021). “Cyperus odoratus“. The IUCN Red List of Threatened Species. Retrieved 26 October 2025.
- ^ NatureServe (3 October 2025). “Cyperus odoratus“. NatureServe Explorer. Arlington, Virginia. Retrieved 21 October 2025.
- ^ a b “Cyperus odoratus L.“. International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens. Retrieved 20 October 2025.
- ^ a b c “Cyperus odoratus L.“. Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 October 2025.
- ^ a b “Cyperus odoratus subsp. odoratus“. Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 21 October 2025.
- ^ a b “Cyperus odoratus subsp. transcaucasicus (Kük.) Kukkonen“. Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 October 2025.
- ^ Tucker, Gordon C. (2012). “Cyperus odoratus“. Jepson eFlora. University and Jepson Herbaria. Retrieved 21 October 2025.
- ^ a b c Tucker, Gordon C.; Marcks, Brian G.; Carter, J. Richard (2002). “Cyperus odoratus“. In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 23. New York and Oxford: Oxford University Press. Retrieved 21 October 2025 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
- ^ “Key to Cyperus“. Flora of the Southeastern United States. Retrieved 22 October 2025.
- ^ Standley (2025).
- ^ a b Tucker & Gandhi (2019).
- ^ “Cyperus odoratus L.“. World Flora Online. Retrieved 22 October 2025.
- ^ “Cyperus engelmannii Steud.“. Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 3 November 2025.
- ^ Dai, Lun-Kai; Tucker, Gordon C.; Simpson, David A. “Cyperus odoratus“. Flora of China. Vol. 23. Retrieved 21 October 2025 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
- Linnaeus, Carl (1753). Species Plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas (1st ed.). Stockholm: Impensis Laurentii Salvii. Retrieved 20 October 2025.
- Naczi, R.F.C. (2017). “Portion of Cyperaceae, the sedge family: Cyperus“. In Naczi, R.F.C.; Abbott, J.R.; and collaborators (eds.). New Manual of Vascular Plants of Northeastern United States and Adjacent Canada, compiled in 2016, 2017. Bronx, NY: New York Botanical Garden Press.
- Standley, Lisa A. (2025). “Cyperus engelmannii in New England”. Rhodora. 126 (1006): 178–182. doi:10.3119/25-08.
- Tucker, Gordon C.; Gandhi, Kanchi N. (2019). “Nomenclatural notes on Cyperus odoratus and related species (Cyperaceae)”. Harvard Papers in Botany. 24 (2): 349–357. doi:10.3100/hpib.v24iss2.2019.n18. ISSN 1938-2944.
