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. Bottlebrush Sedge is a large tufted wetland sedge. The flowering stems (culms) are triangular in cross-section, 8 to 40 inches high, yellow-green to medium green in color, withered remains of old leaves at the base; stem usually smooth but the very upper portion has some roughness.
The leaf blades are alternate along the stem, mid-green in color, smooth, 2.5 to 8.5 mm wide and usually with a 'W' shape formed by the furrow along the length. The underside of the blade can have a fine roughness to the surface.
Leaf sheaths of the basal leaves are tinged with reddish-purple, others yellow-green to medium green. Ligules of all leaves are longer than wide and somewhat V-shaped.
The inflorescence is from 2.5 to 12 cm long, and consists of (1) 2 to 3 (occasionally 4) pistillate (female) spikes, either erect or the lower ones usually pendant on a stalk, with one terminal staminate (male) spike above the pistillate ones. The inflorescence is subtended by a long green bract, 4 to 30 cm, that is longer than the inflorescence itself; this usually lacks a sheath, or if so, less than 4 mm long. Each of the other spikes may have its own shorter bract. The staminate spike is 18 to 35 mm long, narrow and brown at maturity. The pistillate spikes are cylindrical, up to 35 mm long and 12 mm thick (1/2 inch) and rounded on both ends. They appear sharply pointed (and hence the common name of Porcupine Sedge) from the two long teeth on the tip of the perigynia that point straight out. (The bladder-like sacs that enclose the female flower and later the fruit are called perigynia, singular - perigynium).
The perigynia are pale-greenish before maturity, spreading, numerous, densely packed on the spike, with the lowest ones sometimes reflexed; 4.5 to 7.3 mm long and 1.4 to 2.1 mm wide; elliptic in shape, slight inflated; strongly 13 to 21 veined, the veins separated by more than 3x their width and becoming confluent at or just below mid-beak except for two prominent lateral veins; the upper section contracted to a slender beak with two straight teeth 0.3 to 0.9 mm long. The perigynia loosely encloses the achene. The scales on the pistillate perigynia are lanceolate in shape, shorter than the perigynia, margins membranous with fine cilia; with the tips tapered to a rough edged awn that is longer than the body of the scale. (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. The style is straight and somewhat rigid becoming flexible and contorted only at maturity.
Habitat: Bottlebrush 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, hystericina, is derived from hystrix, meaning 'bristly' or 'porcupine like' and refers to the straight rigid style and the two straight teeth on the perigynia of the pistillate spikes. The author names for the plant classification are as follows: First to publish was ‘Muhl’ which refers to Gotthilf Heinrich Ernst Muhlenberg (1753-1815) American Botanist who produced several catalogues of plants after retiring as a Lutheran pastor. His work was recognized but added to by ‘Willd.’ which refers to Carl Ludwig Willdenow (1765-1812), German botanist, a founder of the study of the geographic distribution of plants. He was director and curator of the Botanic Garden of Berlin.
Comparisons: Bottlebrush 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 refer to C. comosa as Bottlebrush Sedge, but that is more properly called Bristly Sedge. The sedges with bristly cylindrical pistillate spikes have generally taken on the common name of 'bottlebrush type.' The closest look-a-like is C. thurberi, Thurber's Sedge, where the beak is shorter and the scales have an awn that is shorter than the scale body. That species is not found in the Midwest. Of the bristly sedges in our area, C. comosa, Bristly Sedge, is the most likely to confuse. It has a similar looking pistillate spike but with two divergent teeth at the apex of the perigynia, larger perigynia, thicker and longer spikes and the perigynia tightly enclosing the achene. It is found principally east and north of a diagonal line drawn from Winona County in the SE, northwestward to Otter Tail and Norman Counties and thus has considerable overlap with C. hystericina.
Below: Bottlebrush Sedge in June. Drawing 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: Upper staminate spike after pollination with pistillate spike below. 2nd photo maturing pistillate spikes October. Underside of the leaf blade shows fine rough hairs.
Below: The base of the stems can be reddish-purple. Basal leaves are short, sheaths have V shaped ligules.
Below: 1st photo - Male and female spikes in flower. 2nd photo - Maturing perigynia.
Below: The perigynia are densely packed on the spikes. The style is rigid and the two teeth of the perigynium are straight.
Below: The root system.
Bottlebrush Sedge is one of over 150 sedges native to Minnesota. This species is found in the majority of counties with the 13 exceptions being scattered throughout the SW quadrant - typically the less marshy or farmland-drained parts of the state. In North America it is widespread, found in most of the U.S. except along the SE coast from Louisiana to North Carolina. In Canada it is known in all the lower provinces.
Eloise Butler first noted this sedge in the Garden on Aug. 3, 1916. Bottlebrush Sedge was still reported as present in the Garden on the 1986 and 2009 Garden 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"