The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Carex disticha
Carex disticha
(tworank sedge)
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Carex disticha Huds.

Common name: tworank sedge

Synonyms and Other Names: Carex distique, two-rank sedge, two rank sedge

Taxonomy: available through www.itis.govITIS logo

Identification: Culms trigonous, scabrous-angled distally, 30–120 cm; vegetative culms somewhat taller. Leaves: basal sheaths brown; sheaths with inner band green, veined, apex hyaline, prolonged 0.7–3 mm; glabrous; ligules 1.8–16 mm; blades 1.8–5.2 mm wide. Inflorescences contracted near middle, 2–7 cm; spikes ascending, ovate, 4–16 × 1.2–9 mm, basal spikes larger than those near middle. Pistillate scales reddish brown at maturity, hyaline margins very narrow or absent, ovate, acute to acuminate, glabrous. Staminate scales reddish brown, narrowly ovate, apex acute to acuminate, glabrous. Perigynia (3.8–)4–5.5(–6.1) × 1.7–2.3 mm; beak (0.8–)1–1.9(–2.3) mm. Achenes brown.

Size: 30-120 cm

Native Range: Eurasia

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Carex disticha are found here.

StateYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Illinois201520162Lower Fox; Spoon
Massachusetts201620161Cape Cod

Table last updated 9/30/2019

† Populations may not be currently present.

Ecology: Carex disticha is a monocotyledonous perennial that produces extensive rhizomatous systems via sympodial growth. Individual ramets and the connections between them appear long-lived, potentially surviving 4 years or longer. Carex disticha is also capable of transporting and sharing resources between ramets across long distances though its ramet system (D’Hertefeldt and Falkengren-Grerup 2002).

Tworank sedge fruits from June–July. It is found in productive habitats, including wet meadows, stream banks, lakeshores, pastures, and disturbed areas (D’Hertefeldt and Falkengren-Grerup 2002).

Means of Introduction: Solid ballast (USEPA 2008). Carex disticha may have been introduced through the shipment of hay, animal forage or bedding, or packing materials (Mills et al. 1993).

Status: Established

Impact of Introduction: thus far still a sporadic introduction

References: (click for full references)

Canadensys. 2012. Carex disticha. Université de Montréal Biodiversity Centre. Available http://data.canadensys.net/vascan/name/Carex%20disticha. Accessed 17 April 2012.

Catling, P.M., A.A. Reznicek, and B.S. Brookes. 1988. The separation of Carex disticha and Carex sartwellii and the status of Carex disticha in North America. Canadian Journal of Botany 66:2323—2330.

Cayouette, J., and P.M. Catling. 1992. Hybridization in the Genus Carex with special reference to North America. Botanical Review 58(4): 351—438.

D’Hertefeldt, T. and U. Falkengren-Grerup. 2002. Extensive physiological integration in Carex arenaria and Carex disticha in relation to potassium and water availability. New Phytologist 156:469—477.

Flora of North America.  2008. www.eFloras.org

Grootjans, A.P., H.W.T. Geelen, A.J.M. Jansen, and E.J. Lammerts. 2002. Restoration of coastal dune slacks in the Netherlands. Hydrobiologia 478: 181—203.

Mills, E.L., J.H. Leach, J.T. Carlton, C.L. Secor. 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. Journal of Great Lakes research 19(1):1-54.

Riutta, T., J. Laine, and E-S. Tuittila. 2007. Sensitivity of CO2 exchange of fen ecosystem components to water level variation. Ecosystems 10: 718—733.

U.S. Army Corps of Engineers (USACE). 2011. Aquatic herbicides. 8 pp.

United States Environmental Protection Agency (US EPA). 2008. Predicting future introductions of nonindigenous species to the Great Lakes. National Center for Environmental Assessment, Washington, DC. 138 pp.

United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). 2012. Plants Database. Available http://plants.usda.gov/java/. Accessed 17 April 2012.

Other Resources:
USDA/NRCS Plants Database

Author: Larson, J. L. Berent, and A. Fusaro

Revision Date: 11/19/2018

Citation Information:
Larson, J. L. Berent, and A. Fusaro, 2020, Carex disticha Huds.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2676, Revision Date: 11/19/2018, Access Date: 9/19/2020

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2020]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [9/19/2020].

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