Sedges differ from grasses by having a 3-angled stem and structurally different flowers where the female flowers are enclosed in a sac like structure called the perigynium, which is subtended by a single scale. Bristly Sedge is a large tufted wetland sedge. The flowering stems (culms) are triangular in cross-section, 10 to 60 inches high, yellow-green in color, lighter brown at the base, usually smooth but the very upper portion may have some roughness.
The leaf blades are alternate along the stem, mid-green in color, smooth, 5 to 16 mm wide and usually with a 'W' shape formed by the furrow along the length.
Leaf sheaths of the basal leaves are pale brown. Ligules of all leaves are longer than wide and V-shaped.
The inflorescence consists of (2) 3 to 6 pistillate (female) spikes, either erect or the lower ones usually pendant on a stalk, with one terminal staminate (male) spike above the pistillate ones. Staminate spikes have been known to be partly female near the base. The inflorescence below the lowest spike is subtended by a long green bract that is much longer (15 to 85 cm) than the inflorescence itself; this usually lacks a sheath. Each of the other spikes has its own shorter bract. The male spike is long (1.5 to 4 inches), narrow and brown. The female spikes are cylindrical, up to 6 cm long and 12 to 18 mm thick and rounded on both ends. They appear bristly (and hence the common name) from the two long teeth on the tip of the perigynia. (The bladder-like sacs that enclose the female flower and later the fruit are called perigynia, singular - perigynium).
The perigynia are 6.2 to 8.7 mm long and 1.1 to 1.8 mm wide, narrowly elliptic to ovate in shape, strongly 14 to 22 veined becoming confluent at or just below mid-beak, leathery, gradually tapering to a poorly define beak with two out-curved teeth 1.3 to 2.1 mm long. The perigynia tightly enclose the achene and are spreading to reflexed at maturity. The scales on the perigynia are reddish-brown with a greenish midrib, linear to ovate in shape, margins with fine cilia; with the tips tapered to a small awn. (Awns are bristle-like appendages at the tip of the seed that can make a twisting response to temperature and humidly changes and thus help the seed to work into the soil).
Seed: Female flowers have 3 stigmas and when mature form a pale brown, smooth, 3-sided achene. Carex achenes usually require 60 days of cold stratification for germination - or sown outside in the Fall.
Habitat: Bristly Sedge is clump forming with short rhizomes. It grows in swamps, marshes, moist swales where it has moist conditions, wet to wet-mesic, full sun only. It has low drought and shade tolerance.
Names: The genus name, Carex, is from the Latin, being the old name for Sedges. The species, comosa, refers to the hairy (bristly) appearance of the female spikes. The author name for the plant classification, ‘Boott’ refers to Francis Boott (1792-1863) American physician and botanist, a founder of Lowell MA. His best known work was a large folio titled Illustrations of the Genus Carex, published in 4 parts in London 1858-1867.
Comparisons: Bristly Sedge is a member of the sedge section Vesicariae whose characteristics are: Rhizomatous root systems, stems reddish-purplish to reddish-brown to brown at the base, sheath fronts membranous, blades V or W shaped to somewhat flat, blades mostly wider that 4 mm; racemose inflorescences with 2 to 10 spikes; perigynia 0 to 25 veined, slightly inflated, 2 to 12 mm long, with the apex tapering or abruptly forming a a beak; scales green to dark brown; achenes usually 3 sided and almost as large as the perigynia body. Some sources call this species Bottlebrush Sedge, but that is more properly assigned to Carex hystericina. The sedges with bristly cylindrical pistillate spikes have generally taken on the common name of 'bottlebrush type.' Of the bristly hedges, C. comosa has the distinguishing two divergent teeth at the apex of the perigynia and achenes smooth. The closest look-a-like is C. pseudocyperus, Cypress-like Sedge, where the beak is straight or only slightly out-curved, only 0.7 to 1.2 mm long, and the spikes are only 9 to 12 mm thick. It is found extensively in northern Minnesota and in a few counties of the metro area but not in SE Minnesota like C. comosa.
Above: A group of pistillate spikes with the remains of one staminate spike (brown) visible. Drawing of Bristly Sedge from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: The perigynia developed on the female spikes, summer and fall view. Note the beak with the split outward pointed awns.
Below: Details of the sheath area. Note the roughness on the edge of the stem.
Below: 1st photo - The blade forms a flattened W shape. 2n photo - A mature perigynium - much longer than wide, with two outcurved beaks. Photo ©Linda Curtis, Wisconsin Flora.
Bristly Sedge is one of over 150 sedges native to Minnesota. This species is found principally east and north of a diagonal line drawn from Winona County in the SE, northwestward to Otter Tail and Norman Counties. In North America it is found in most of the U.S. except the drier SW and in Canada it is known in British Columbia, Ontario, Quebec, New Brunswick and Nova Scotia.
Bristly Sedge was reported as present in the Garden on the 2009 census, but not on the previous 1986 census.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"