Cyperus odoratus
Species of plant
From Wikipedia, the free encyclopedia
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.
| Fragrant flatsedge | |
|---|---|
| |
Scientific classification  | |
| 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] | |
|
Cyperus odoratus
C. o. subsp. odoratus
C. o. subsp. transcaucasicus
| |
Description
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.[11]
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]
Taxonomy
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").[13]
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
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]
