Acorus calamus - L.
European Sweetflag
Other Common Names: calamus
Taxonomic Status: Accepted
Related ITIS Name(s): Acorus calamus L. (TSN 564989)
French Common Names: acore roseau
Unique Identifier: ELEMENT_GLOBAL.2.134366
Element Code: PMACO01020
Informal Taxonomy: Plants, Vascular - Flowering Plants - Other flowering plants
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Arales Acoraceae Acorus
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Acorus calamus
Taxonomic Comments: As treated by Kartesz, Acorus calamus excludes the plants sometimes treated as Acorus calamus var. americanus, which (following Thompson, 1995, Ph.D. diss., U.Illinois) is treated by him as Acorus americanus. Kartesz (1999) considers at least some material of both species to be native in North America. LEM 8Jun98 & 14Jun99.

There has been confusion or disagreement as to the native status of this species in North America (Gleason and Cronquist 1963, Great Plains Flora Association 1986, Hitchcock and Cronquist 1976). Kartesz (1999) now recognizes two species (sometimes treated by others as varieties) of Acorus in North America. Under this taxonomy, Acorus americanus is the name given the native North American taxon, while A. calamus refers to the primarily Eurasian taxon, which is also considered native in parts of its present range in North America. Most botanists also consider these two taxa separate; however, there remains a great deal of disagreement about whether A. calamus is native anywhere in North America or not. The two are superficially very similar and difficult to distinguish, but they differ in chromosome number as well as other important characteristics (Michael Oldham pers. comm.). A commonly cited morphological difference between these taxa is the presence of only one raised vein running the length of the basal leaves in the Eurasian taxon, whereas the native North American taxon has two or more such veins (Swink and Wilhelm 1994). As further evidence that these taxa are not conspecific, one herbal remedy guide reports that the Eurasian material contains a carcinogen which North American material lacks (Tierra 1990).

Packer and Ringius (1984) contains information regarding the taxonomic status and distribution of Acorus in Canada.

There remains a great deal of confusion and disagreement among botanists regarding this species. Many reports of Acorus calamus throughout North America probably belong to A. americanus instead.
Conservation Status
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NatureServe Status

Global Status: G4?
Global Status Last Reviewed: 21Jan2000
Global Status Last Changed: 31Jan2000
Rounded Global Status: G4 - Apparently Secure
Reasons: It is likely that this species is in rangewide decline due to the disappearance and degradation of its wetland habitats. The recent splitting of Acorus at the species level means that it is uncertain for many occurrences whether they are A. calamus or A. americanus. When this is sorted out it may become evident that one species is rarer or more common than originally thought.
Nation: United States
National Status: NU
Nation: Canada
National Status: NNA (17Jun2016)

U.S. & Canada State/Province Status
United States Alabama (SNA), Arkansas (SNR), California (SNR), Colorado (S1), Connecticut (SNR), Delaware (SNA), District of Columbia (SNR), Georgia (SNA), Illinois (SNR), Indiana (SNR), Iowa (S3), Kansas (SNR), Kentucky (SNA), Louisiana (SNR), Maine (SNR), Maryland (SNR), Massachusetts (SNR), Michigan (SNR), Minnesota (SNA), Mississippi (S1), Missouri (SNR), Nebraska (SNR), New Hampshire (SNR), New Jersey (SNA), New York (SNA), North Carolina (S2S3), Ohio (SNR), Oklahoma (SNA), Oregon (SNR), Pennsylvania (SNA), Rhode Island (SNR), South Carolina (SNR), South Dakota (SNR), Tennessee (SNR), Texas (SNR), Vermont (SNR), Virginia (SNA), West Virginia (SNA), Wisconsin (SNR)
Canada New Brunswick (SNA), Nova Scotia (SNA), Ontario (SNA), Prince Edward Island (SNA), Quebec (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Please see Kartesz (1999) for the updated global range information for Acorus calamus and A. americanus. In North America, A. calamus is mostly concentrated in plains and eastern locations. This species is also reported from Eurasia in the former Soviet Union (Hulten, 1968; Gleason and Cronquist 1963). A. calamus is reported to occur throughout most of the eastern U.S. except Florida, and also in Washington, Oregon, California, South Dakota, Nebraska, Kansas, Oklahoma, and Texas (Kartesz 1999). It is considered an exotic in Ontario (Ontario Natural Heritage Information Centre), Nebraska (Nebraska Natural Heritage Program), Missouri (Missouri Department of Conservation), and Kansas (Kansas Natural Features Inventory). It is historical in Delaware (Delaware Natural Heritage Program) and in Colorado. The Missouri populations were reportedly introduced by settlers for medicinal use (Tim Smith pers. comm.). It is known from seven counties in South Dakota (South Dakota Natural Heritage Database). It is reported from southern lower Michigan (Michigan Natural Features Inventory). It is reported from all counties in Maine (Maine Natural Areas Program).

Packer and Ringius (1984) contains information regarding the taxonomic status and distribution of Acorus in Canada. Only Acorus americanus (A. calamus var. americanus) occurs in Manitoba (Manitoba Conservation Data Centre).

Number of Occurrences: 81 to >300
Number of Occurrences Comments: At least a few hundred North American occurrences for this species known, at least some of which may be native as well as a sizable Eurasian range (cf. Hulten, 1968). "Uncommon" in California (Hickman 1993). There is one population reported from Alaska (Hulten 1968). It is reported to be "not very common" in Nebraska (Nebraska Natural Heritage Program). It is reported to be "common" in Maine (Maine Natural Areas Program). The plant is not rare in New Hampshire (New Hampshire Natural Heritage Inventory). Fourteen occurrences are reported from seven counties in South Dakota (South Dakota Natural Heritage Database). Roughly one hundred occurrences of Acorus are reported from Ontario, including occurrences of both A. calamus and A. americanus (Ontario Natural Heritage Information Centre). Five populations are reported from the Okeefenokee Swamp in southern Georgia, but the taxonomic status of these occurrences is uncertain. Both taxa are genuinely rare in Georgia (Georgia Natural Heritage Program). It is infrequent in marshes, on pond margins, along streams, and in ditches throughout the state of Kentucky (Kentucky Natural Heritage Program). It is reported as common in wetlands across the state of New York (New York Natural Heritage Program). Acorus is common in Indiana in wet fields, ditches, and marshes, but the Indiana NHP has not tried to distinguish the two species of Acorus, and their relative abundance in the state is unknown (Indiana Natural Heritage Data Center). 40 to 50 occurrences are reported from Kansas (Kansas Natural Features Inventory). One occurrence is documented by the Mississippi Natural Heritage Program for the state (Mississippi Natural Heritage Program). A. calamus is rare in Texas with a few wetland occurrences known from the northeastern corner of the state (Texas Natural Heritage Program). It is known historically from three populations in Colorado, all of which appear to have been extirpated. Worldwide, there are probably many thousands of populations.

Overall Threat Impact Comments: An individual with the U.S. herbal medicinal industry states that trade in the plant is modest, on the order of 2000-3000 pounds per year, and that it is the root that is used (McGuffin pers. comm.).

In northeastern South Dakota, the Dakota tribe collects and utilizes an unknown quantity of this plant (David Ode pers. comm.). It is reportedly collected in Canada and the northeastern U.S. for sale on the herb market (Robyn Klein pers. comm.).

Acorus calamus is listed by the United Plant Savers At Risk Forum on their "To Watch" list. This list consists of "herbs which are broadly used in commerce and which, due to over-harvest, loss of habitat, or by the nature of their innate rareness or sensitivity are either at risk or have significantly declined in numbers within their current range." (United Plant Savers 2000)

With the general disappearance and degradation of wetlands, the habitat of this species continues to shrink. Because it is associated with relatively undisturbed habitats when compared with Acorus calamus, A. americanus is probably more threatened in some parts of its range as more undisturbed wetlands become disturbed. Replacement of A. americanus by A. calamus is possible as more wetland habitats become disturbed where the two species overlap. Channelization of springruns has been implicated as a threat to occurrences of this species in Georgia (Tom Patrick pers. comm.). Urban sprawl is causing widespread degradation of potential habitat for this species in southern Lower Michigan (Mike Penskar pers. comm.). Lack of monitoring resources available to properly document the population trends for this species are cited as a threat in Mississippi (Mississippi Natural Heritage Program).

Short-term Trend Comments: Increasing in California (Hickman 1993). Declining in Colorado, where its original habitat was wetlands in piedmont valley meadows (Weber and Wittmann 1996b). Claims of population trends in North America may sometimes be skewed according to an individual's belief or assumption regarding the native status of this species.

Intrinsic Vulnerability Comments: A wetland plant, it could be affected by hydrological modifications.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Please see Kartesz (1999) for the updated global range information for Acorus calamus and A. americanus. In North America, A. calamus is mostly concentrated in plains and eastern locations. This species is also reported from Eurasia in the former Soviet Union (Hulten, 1968; Gleason and Cronquist 1963). A. calamus is reported to occur throughout most of the eastern U.S. except Florida, and also in Washington, Oregon, California, South Dakota, Nebraska, Kansas, Oklahoma, and Texas (Kartesz 1999). It is considered an exotic in Ontario (Ontario Natural Heritage Information Centre), Nebraska (Nebraska Natural Heritage Program), Missouri (Missouri Department of Conservation), and Kansas (Kansas Natural Features Inventory). It is historical in Delaware (Delaware Natural Heritage Program) and in Colorado. The Missouri populations were reportedly introduced by settlers for medicinal use (Tim Smith pers. comm.). It is known from seven counties in South Dakota (South Dakota Natural Heritage Database). It is reported from southern lower Michigan (Michigan Natural Features Inventory). It is reported from all counties in Maine (Maine Natural Areas Program).

Packer and Ringius (1984) contains information regarding the taxonomic status and distribution of Acorus in Canada. Only Acorus americanus (A. calamus var. americanus) occurs in Manitoba (Manitoba Conservation Data Centre).

U.S. States and Canadian Provinces
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States AL, AR, CA, CO, CT, DC, DEexotic, GAexotic, IA, IL, IN, KS, KYexotic, LA, MA, MD, ME, MI, MNexotic, MO, MS, NC, NE, NH, NJexotic, NYexotic, OH, OK, OR, PAexotic, RI, SC, SD, TN, TX, VAexotic, VT, WI, WVexotic
Canada NBexotic, NSexotic, ONexotic, PEexotic, QCexotic

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
AL Baldwin (01003)*, Jackson (01071), Limestone (01083), Marshall (01095)
CO Boulder (08013)*, Denver (08031), Larimer (08069)
MS Carroll (28015), Forrest (28035), Leflore (28083), Union (28145)
OK Cleveland (40027)*, McClain (40087)*, Ottawa (40115), Seminole (40133), Stephens (40137)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Mobile - Tensaw (03160204)+*, Upper Leaf (03170004)+
06 Guntersville Lake (06030001)+, Wheeler Lake (06030002)+
08 Little Tallahatchie (08030201)+, Upper Yazoo (08030206)+
10 Upper South Platte (10190002)+, Middle South Platte-Cherry Creek (10190003)+, Clear (10190004)+, St. Vrain (10190005)+*, Cache La Poudre (10190007)+
11 Lake O' the Cherokees (11070206)+, Lower Canadian-Walnut (11090202)+*, Lower North Canadian (11100302)+, Farmers-Mud (11130201)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A tall (to 2m) (Gleason and Cronquist 1963) perennial (Hickman 1993) wetland plant with narrow, cattail-like leaves and tiny yellowish flowers clustered on a stalk. This species has a history of use for food, medicine, and ritual (Fernald and Kinsey 1943, Great Plains Flora Association 1986, Tierra 1990).
Technical Description: From CNHP Wetland Guide 2012: Growth Habit: perennial, creeping rhizomes with brownish exteriors and white, fleshy interiors.
Stems:
Leaves: erect, sharp-pointed, sword-shaped fan out from a pinkish base, up to 5 feet in length, mid-vein is usually off-center.

Flower Stem/Scape: arises from base of outer leaves, triangular in cross section, spathe extends beyond the scape.

Flowers: perfect, single, cylindrical 2- to 4- inch spike or spadix angles out, slightly curved and crowed with small yellowish green to brown flowers.

Fruit: berry with leathery pericarp


Diagnostic Characteristics: From CNHP Wetland Guide 2012: Main Characteristics:
·Resembles a cattail but the leaves are sword-like as in Iris
·Crushed foliage and rhizomes have a sweet fragrance

Habitat Comments: Shallow waters and wetlands, including ponds, marshes, swamps, and quiet riverbanks or floodplains (Gleason and Cronquist 1963, Fernald and Kinsey 1943). A. americanus is reported to occur in more stable habitats, whereas A. calamus is reported from more disturbed habitats, such as wet pastures and artificial ditches (Swink and Wilhelm 1994).
Economic Attributes
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Economically Important Genus: Y
Commercial Importance: Indigenous crop, Minor cash crop
Economic Uses: FOOD, MEDICINE/DRUG, LANDSCAPING, OTHER USES/PRODUCTS
Production Method: Wild-harvested
Economic Comments: There are no known differences between the uses for Acorus calamus and A. americanus at this time. This plant has a long history of use by Native Americans, who have used it for a variety of cures. It is used widely by drum singers to help keep the throat moist (Robyn Klein pers. comm.). Small pieces of the plant were sucked while singing during powwows, and it was used as a cough remedy. Native Americans also spread the leaves in their lodgings to give a pleasing scent. Early settlers used the plant as a candy or a kind of throat lozenge (Mike Penskar pers. comm.). It is used by herbalists as a treatment for ailments of the throat and lungs, but only in small amounts as part of an herbal formula (Robyn Klein pers. comm.). It is recommended as a component of formulas for quitting tobacco and marijuana smoking (Tierra 1990). It was probably introduced in many parts of its range by settlers for medicinal use. See Tierra (1990) for a very detailed summary of medicinal applications for this plant.

Euell Gibbons has documented many uses for this plant in his popular books on eating and using plants.

Prices for this species were found as follows:

Unknown location: $4.50/lb (Ed Fletcher pers. comm.)

U.S., internet: $3.25/packet of seeds

U.S., internet: $1.16/oz

U.S., mail order: $8.50/lb of wild-harvested material, $9.50/lb of powdered root

U.S., mail order: $1.08/oz dried root, $8.65/lb (1-4 lbs), $8.20/lb (5-24 lbs), $7.20/lb (25 lbs) (plant material from Poland)

U.S., mail order: $13.49/one-third oz. root essential oil (wholesale), $22.49 (retail)

Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 21Jan2000
NatureServe Conservation Status Factors Author: Susan Spackman, David Anderson, and Steve Thomas (1/00); rev. Eric Nielsen (1/00)

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Flora of North America Editorial Committee. 2000. Flora of North America north of Mexico. Vol. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford Univ. Press, New York. xxiii + 352 pp.

  • Gleason, H.A., and A. Cronquist. 1963. Manual of vascular plants of northeastern United States and adjacent Canada. D. Van Nostrand Company, New York, NY. 810 pp.

  • Hickman, J. C., ed. 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, CA. 1400 pp.

  • Hulten, E. 1968. Flora of Alaska and Neighboring Territories. Stanford University Press, Stanford, CA.

  • Hulten, E. 1968. Flora of Alaska and neighboring territories. Stanford Univ. Press, Palo Alto, CA. 1008 pp.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Packer, J.G., and G.S. Ringius. 1984. The distribution and status of Acorus (Araceae) in Canada. Canadian Journal of Botany 62(11): 2248-2252.

  • Swink, F., and G. Wilhelm. 1994. Plants of the Chicago Region. Morton Arboretum. Lisle, Illinois.

  • Tierra, M. 1990. The Way of Herbs. Simon and Schuster Inc., New York, NY. 378pp.

  • Tierra, M. 1990. The Way of Herbs. Simon and Schuster Inc., New York, NY. 378pp.

  • Weber, W.A., and R.C. Wittmann. 1996b. Colorado flora: Western slope. Univ. Press of Colorado, Niwot, Colorado. 496 pp.

  • Weber, William A. and Ronald C. Wittmann. 1996. Colorado Flora: Eastern Slope.

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