Common Bladder Sedge
Carex intumescens var. intumescens
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CLASSIFICATION: What’s in a name?
Scientific Name: Carex intumescens var. intumescens. The genus, Carex, comes from Greek kairos “to cut”, referring to some species’ sharp-edged leaves. The epithet, intumescens comes from Latin, and means swollen, referring to the inflated sacs which the seeds are contained in.6
Common Name: Common Bladder Sedge. The word sedge is derived from the Old English secg which in turn is derived from the Proto Indo-European sek meaning “to cut” again referring to the sharp, scabrous leaves and sheaths of some species.7 “Bladder” refers to the inflated perigynia which the seeds are contained within.
Family: Cyperaceae (Sedge family): This is a massive family of over 5,000 species, found worldwide, with many genera of graminoids (grasslike plants). In Virginia, there are around 200 species in the genus Carex alone! Papyrus (Cyperus papyrus) and water chestnuts (Eleocharis dulcis) are in the sedge family, and many other species are cultivated as ornamentals.
IDENTIFICATION: What does it look like?
Average Height: 12-18 inches
Description: A medium-sized sedge, clump-forming or in small, loose colonies. Leaves are triangular in cross-section, and grasslike. The male and female flowers are borne in separate clusters on the same stalk, with the male situated above the female. Male (staminate) flowers are tiny and hidden within small scales, with the anthers hanging out. The female (pistillate) flowers sit lower and have inflated bases, hinting at the bladderlike sacs which develop after fertilization. Sedge seeds are contained within a structure called a perigynium, which can vary greatly between species. Many wetland sedges, including C. intumescens, have inflated perigynia as a flotation aid in order to better disperse the seeds in flooded habitats.
Bloom time: Apr – Jul
Notes: This is one of a number of wetland sedge species with inflated sac-like perigynia. Another variety, var. fernaldii, can be found at higher elevations in southwestern Virginia.9 The most likely species to be confused with bladder sedge is Gray’s sedge (C. grayi). It differs in having perigynia spreading in all directions (vs mostly spreading outwards and upwards) round seeds (vs. triangular)4, and averages more perigynia per head up to 35 (vs. a maximum of 20.)3,9
LOCATION: Where is it at home?
Range: Found commonly across Virginia, but absent from the highest elevations.8 A large native range in North America, from Florida west to Texas and north into Canada. A disjunct population occurs in the Black Hills of southwestern South Dakota and northeastern Wyoming.1
Geology/Soil: Found on a wide range of geologic formations and soil types.
Habitat: Wetlands, particularly in forested areas. Can be found in swamps, seepages, streambanks, pond edges, marshes, bogs, wet grasslands, and flatwoods.
CONNECTIONS: What are its relationships to other plants, animals, and humans?
Flora associations: Grows with a wide variety of plant species across its range. In the Virginia Piedmont, common associates include red maple (Acer rubrum), willow oak (Quercus phellos), green ash (Fraxinus pennsylvanica), spicebush (Lindera benzoin), smooth alder (Alnus serrulata), southern lady fern (Athyrium asplenioides), false nettle (Boehmeria cylindrica), and orange jewelweed (Impatiens capensis).
Fauna associations: Sedges support a wide variety of insect life, including the Appalachian brown butterfly (Satyrodes appalachia), various skippers (Hesperiidae), and a whole host of other herbivorous insects. The seeds are an important food source for wetland birds such as dabbling ducks, sparrows, and the American woodcock (Scolopax minor).5
Human associations: No human uses are known for Carex intumescens var. intumescens. However, many species of Carex are used in Indigenous basketry.2
We want these plants to thrive and for everyone who gets to visit the park to enjoy them, so remember – don’t pick flowers or other parts of the plant!!
Bibliography & Definitions
1 “2013 BONAP North American Plant Atlas. TaxonMaps.” Bonap.net, bonap.net/Napa/TaxonMaps/Genus/County/Carex. Accessed 21 May 2024.
2 “BRIT – Native American Ethnobotany Database.” Naeb.brit.org, naeb.brit.org/uses/search/?string=carex+. Accessed 21 May 2024.
3 “Carex intumescens (Greater Bladder Sedge): Go Botany.” Gobotany.nativeplanttrust.org, gobotany.nativeplanttrust.org/species/carex/intumescens/#:~:text=Greater%20bladder%20sedge%20has%20lustrous. Accessed 21 May 2024.
4 “Distinction between Carex Intumescens and C. Grayi.” Botanical Gazette, vol. 4, no. 10, Oct. 1879, pp. 221–224, https://doi.org/10.1086/325294. Accessed 26 July 2021.
5 Hilty, John. “Bladder Sedge (Carex intumescens).” Illinoiswildflowers.info, 2013, www.illinoiswildflowers.info/grasses/plants/bladder_sedge.html.
6 “Intumescent | Etymology of Intumescent by Etymonline.” Www.etymonline.com, www.etymonline.com/word/intumescent. Accessed 21 May 2024.
7 “Sedge | Etymology of Sedge by Etymonline.” Www.etymonline.com, www.etymonline.com/word/sedge. Accessed 21 May 2024.
8 Virginia Botanical Associates. “Digital Atlas of the Virginia Flora | Browsing Family Cyperaceae.” Vaplantatlas.org, vaplantatlas.org/index.php?do=browse:family&id=22. Accessed 21 May 2024.
9 Weakley, Alan S, et al. Flora of Virginia. Fort Worth, Tex Botanical Research Institute Of Texas Press, 2013.
Definitions:
Disjunct: Separated geographically from its primary range.
Anther: The part of a flower which bears pollen.
Perigynium: A structure which surrounds the seed of a sedge (Carex). Plural perigynia.