Eriophorum (cottongrass, cotton-grass or cottonsedge) is a genus of flowering plants in the family Cyperaceae, the sedge family. They are found in the cool temperate, alpine, and Arctic regions of the Northern Hemisphere, primarily in the middle latitudes of North America, Europe, and Asia.
Description Eriophorium species are perennial herbaceous plants that persist by means of underground rhizomes. Stems (called culms) grow singly or in clumps (i.e., cespitose). Both basal leaves and stem leaves are present, although the latter are bladeless in some species. The terminal inflorescence is either a single erect spikelet or multiple spikelets on peduncles of various lengths. In the case of multiple spikelets, the inflorescence is subtended by one or more leaf-like bracts. Individual flowers have 10 or more smooth perianth bristles that greatly elongate and remain attached to the achene during fruiting. The bristles facilitate seed dispersal by wind. In cold Arctic regions, the bristles also serve as insulation by trapping solar radiation and thereby increasing the temperature of the reproductive organs.
Identification keys often begin with a pair of alternatives that implicitly divide the genus into two mutually exclusive sections:
Eriophorum section Vaginata: one erect spikelet; no leaf-like bracts at the base of the inflorescence; stem leaves absent or, if present, either bladeless or with blade not more than 1 cm long Eriophorum section Phyllanthela: multiple spikelets (rarely one); one or more leaf-like bracts at the base of the inflorescence; uppermost stem leaf with a blade at least 1 cm long
Besides the number of spikelets and the presence of bracts and stem leaves, other characters may be used for identification, including: the length of the uppermost leaf blade relative to its sheath; the number of bracts (0, 1, or more than 1); the length and orientation of the bracts; the length of the peduncles; and the color of the bristles.
Taxonomy In the first edition of Species Plantarum published in 1753, the Swedish botanist Carl Linnaeus established genus Eriophorum by recognizing four species: Eriophorum vaginatum, Eriophorum polystachion, Eriophorum virginicum, and Eriophorum alpinum. In the second edition published in 1762, Linnaeus added a fifth species, Eriophorum cyperinum. The name Eriophorum is the primary generic name in use today. Although the names of some of the species have changed, the number of recognized taxa in genus Eriophorum has remained more-or-less the same since 1994.
In the fifth edition of Genera Plantarum published in 1754 (intended to accompany the first edition of Species Plantarum), Linnaeus referenced the prior work of the Italian botanist Pier Antonio Micheli and the French botanist Joseph Pitton de Tournefort. In 1729, Micheli described genus Linagrostis, including an illustration of an unidentified plant. (The plant was later identified to be Eriophorum vaginatum.) Tournefort coined the French name Linaigrette (Latin: Linagrostis) in 1694, but his contribution became better known in Europe when his book was translated to Latin in 1719.
The French naturalist and mineralogist Jean-Étienne Guettard resurrected the pre-Linnaean name Linagrostis in 1750, and again in 1754, but Linagrostis is regarded as a synonym for Eriophorum After Guettard, the name Linagrostis was redescribed by numerous botanists, including John Hill (1756), Johann Gottfried Zinn (1757), and Giovanni Antonio Scopoli (1771), but all three published illegitimate names since Linagrostis takes precedence. Scopoli's description of Linagrostis is notable, however, since it is explicitly based on the early work of Tournefort. The names Linagrostis vaginata , Linagrostis alpina , and Linagrostis polystachia are synonyms for the corresponding names introduced by Linnaeus in 1753.
The Austrian botanist and mycologist Eduard Palla established genus Eriophoropsis in 1896 by segregating Eriophorum virginicum into a new genus. The name Eriophoropsis is both a synonym for Eriophorum and the basionym of Eriophorum subgen. Eriophoropsis , the latter described by the Canadian botanist Louis-Florent-Marcel Raymond in 1954.
Species , the following species are accepted by Plants of the World Online (POWO):
Name/Author Year described Year published Group Distribution Eriophorum angustifolium 1782 1782 Multispicate Widespread across Europe, Asia, North America Eriophorum arcticum 1994 2023 Unispicate Siberia Eriophorum brachyantherum 1856 1856 Unispicate Scandinavia, northern Russia, Mongolia, Korea, Alaska, northern Canada Eriophorum callitrix 1831 1831 Unispicate Siberia, Russian Far East, Alaska, Canada, Greenland, Montana, Wyoming Eriophorum chamissonis 1831 1831 Unispicate Siberia, Russian Far East, Korea, Mongolia, Alaska, Canada, Greenland, northern and western United States Eriophorum gracile 1799 1799 Multispicate Much of Europe; northern and Central Asia; China, Tibet, Mongolia, Alaska, Canada, northern United States Eriophorum humile 1838 1838 Unispicate Altai, Tuva, Kazakhstan, Mongolia, Amur Eriophorum latifolium 1800 1800 Multispicate Much of Europe; Caucasus, Turkey, Mongolia Eriophorum scheuchzeri 1800 1800 Unispicate Much of Europe; northern and Central Asia including Siberia, Xinjiang, Himalayas, Alaska, Greenland, Canada, mountains of western United States Eriophorum tenellum 1818 1818 Multispicate Eastern Canada and northeastern United States from Nunavut and Labrador to New Jersey Eriophorum tolmatchevii 1994 1994 Unispicate Krasnoyarsk, Yakutiya Eriophorum transiens 1959 1959 Multispicate Guizhou Eriophorum triste 1869 1950 Multispicate Finland, North America and temperate regions of Asia Eriophorum vaginatum 1753 1753 Unispicate Widespread across Europe, Asia, North America Eriophorum virginicum 1753 1753 Multispicate Eastern North America from Labrador to Tennessee, west to Michigan Eriophorum viridicarinatum 1844 1905 Multispicate Canada including Arctic territories; northern United States
The following natural hybrids are also accepted by POWO:
Name/Author(hybrid formula) Year described Year published Distribution Eriophorum × beringianum (E. angustifolium × E. chamissonis) 1957 1957 Alaska including Aleutians; Magadan region of Russia Eriophorum × churchillianum (E. triste × E. vaginatum) 1957 1957 Alaska Eriophorum × fellowsii (E. virginicum × E. viridicarinatum) 1905 1995 Ontario, Maine, Massachusetts Eriophorum × gracilifolium (E. gracile × E. latifolium) 1994 1994 European Russia Eriophorum × medium (E. chamissonis × E. scheuchzeri) 1857 1857 Scattered locations in Finland, Norway, Russia, Alaska, Quebec, Labrador Eriophorum × pylaieanum (E. chamissonis × E. vaginatum) 1951 1951 Scattered locations in Canada and Alaska Eriophorum × rousseauianum (E. angustifolium × E. scheuchzeri) 1950 1950 Alaska, Quebec
World Flora Online (WFO) accepts all of the above species and hybrids except Eriophorum arcticum. In addition, WFO accepts Eriophorum × polystachiovaginatum whereas POWO does not.
Other names Of the five species described by Linnaeus in 1753 and 1762, three of the names are no longer in use. Eriophorum polystachion is a rejected name, now considered to be a synonym for Eriophorum angustifolium subsp. angustifolium, while Eriophorum alpinum and Eriophorum cyperinum are synonyms for Trichophorum alpinum and Scirpus cyperinus , respectively.
The Swedish mycologist and botanist Elias Magnus Fries described Eriophorum russeolum in 1836. Some authors consider Eriophorum russeolum to be a synonym for Eriophorum chamissonis , while others consider the two names to refer to separate species.
In 1942, the American agrostologist and botanist Alan Ackerman Beetle placed the species Scirpus criniger into genus Eriophorum. In 2012, Eriophorum crinigerum was segregated into genus Calliscirpus, and so Eriophorum crinigerum is a synonym for Calliscirpus criniger .
In 1957, the Canadian botanist Louis-Florent-Marcel Raymond placed the species Scirpus scabriculmis into genus Eriophorum. In 2019, Eriophorum scabriculme was segregated into genus Trichophorum. Hence Eriophorum scabriculme is a synonym for Trichophorum scabriculme .
The invalidly published name Eriophorum × polystachiovaginatum is a synonym for Eriophorum × beauverdii but the latter is unplaced by POWO.
Subdivision In 1849, the Swedish botanist Nils Johan Andersson placed the European species of Eriophorum into two new sections:
Eriophorum section Vaginata: Eriophorum vaginatum Eriophorum capitatum (a synonym for Eriophorum scheuchzeri) Eriophorum russeolum (a synonym for Eriophorum chamissonis)
Eriophorum section Phyllanthela: Eriophorum angustifolium Eriophorum latifolium Eriophorum gracile
In 1905, the American botanist Merritt Lyndon Fernald placed the North American species of Eriophorum into Andersson's sections as follows:
Eriophorum section Vaginata: Eriophorum scheuchzeri Eriophorum chamissonis Eriophorum vaginatum Eriophorum callitrix Eriophorum opacum n. comb. (a synonym for Eriophorum brachyantherum)
Eriophorum section Phyllanthela: Eriophorum gracile Eriophorum tenellum Eriophorum polystachion (a synonym for Eriophorum angustifolium) Eriophorum viridicarinatum n. comb. Eriophorum virginicum
Phylogeny Based on phylogenetic analyses, Eriophorum forms a well‐supported clade nested within the genus Scirpus, which suggests the latter is paraphyletic. To resolve this issue, there are at least two options: 1) merge Eriophorum into Scirpus, or 2) split Scirpus into a series of new genera. , there has been insufficient data for a majority of botanists to prefer one option or the other.
Eriophorum virginicum, Eriophorum tenellum, and Eriophorum gracile form a strongly supported clade that is sister to the rest of the genus. The clade is distinguished by having glumes (scales at the base of each flower in a spikelet) with many prominent nerves, whereas the glumes of the remaining species possess a single prominent midnerve.
Within a weakly supported clade of unispicate species (i.e., species with a single spikelet), Eriophorum russeolum and Eriophorum scheuchzeri form a strongly supported, monophyletic species complex characterized by a rhizomatous habit, up to 7 sterile glumes, and by glumes with well-defined hyaline margins (i.e., with thin, translucent edges). In contrast, in the sister clade to this complex (Eriophorum vaginatum, Eriophorum brachyantherum, and Eriophorum callitrix) each species has a caespitose habit and more than 12 sterile glumes that generally lack clear hyaline margins.
Distribution and habitat Eriophorum species are found in the cool temperate, alpine, and Arctic regions of the Northern Hemisphere, primarily in the middle latitudes of North America, Europe, and Asia.
North America: E. angustifolium, E. brachyantherum, E. callitrix, E. chamissonis, E. gracile, E. scheuchzeri, E. tenellum, E. triste, E. vaginatum, E. virginicum, E. viridicarinatum Europe: E. angustifolium, E. brachyantherum, E. chamissonis, E. gracile, E. latifolium, E. scheuchzeri, E. triste, E. vaginatum Asia: E. angustifolium, E. arcticum, E. brachyantherum, E. callitrix, E. chamissonis, E. gracile, E. humile, E. latifolium, E. scheuchzeri, E. tolmatchevii, E. transiens, E. triste, E. vaginatum
Preferred habitats include bogs, fens, meadows, and alpine tundra.
Uses Paper and the wicks of candles have been made of its fiber, and pillows stuffed with the same material. The leaves were formerly used in treating diarrhea, and the spongy pith of the stem for the removal of tapeworm.
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