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. Sprengel's Sedge is a cool season native perennial sedge forming clumps. The flowering stems (culms) are triangular in cross-section, 12 to 36 inches high, green in color, usually smooth but within the inflorescence they may have some roughness. These rise from the rhizome and at maturity the flowering stem is much longer than the leaves. Bases are usually brown, covered with the slender fibers of the prior years leaves. There are also non-flowering stems. Stems are 0.5 to 0.7 mm thick.
The leaf blades are dark-green in color, smooth on the back and slightly rough on the upper surface and margins. They are flat except for a prominent mid-vein ridge which forms a V or M shape when young; 2.5 to 4 mm wide and much shorter than the stems. The leafy part of the plant is usually around 12 inches high.
Leaf sheaths are green to green-translucent on the back and white-translucent on the front, usually smooth. The basal sheaths may be tinged with brown and all have blades.
The inflorescence consists of both pistillate (female) spikes, and staminate spikes. Staminate spikes (there may be several) are at the top of the stem and the terminal spike, while staminate, may have a few pistillate florets at the base making the terminal spike what is referred to as 'androgynous', but that is a rarer case. The terminal spike can be 10 to 20 mm long, 1.5 to 2 mm wide and on a short (5 to 15 mm) stalk. Those upper lateral spikes are usually all staminate or androgynous, that is with staminate florets above and some pistillate florets below. These spikes are linear and less than 20 mm long. The lower lateral spikes number 4 to 5, and are all pistillate, cylindric, 10 to 35 mm long, 8 to 10 mm wide, and on slender stalks as long or longer than the spikes, drooping at maturity, widely separated from each other, one at each stem node. The nodes of the inflorescence are subtended by green bracts with sheaths 3 to 5 mm long, the lower bracts may equal the length of the inflorescence, but frequently are shorter. The pistillate spikes have 10 to 40 perigynia placed about 1 mm apart but those on the upper mixed spikes will be more crowded at the top of the spike. (The bladder-like sacs that enclose the female flower and later the fruit are called perigynia, singular - perigynium).
The perigynia are shiny-tan to green when immature, ovoid-ellipsoid in shape, 4.5 to 6.5 mm long by 1.5 to 2.0 mm wide, 2-ribbed, vein-less, with an acute base and abruptly tapering to a smooth beak, with two teeth that are nearly as long as the body of the perigynia. Teeth have rough edges. The perigynia tightly envelopes the achene. The scales on the perigynia are whitish, sometimes tinged with chestnut brown and with a narrow green mid-rib, ovate to oblong in shape, shorter than the perigynium body with the tips long pointed. Stamens number 3 and female flowers have 3 slender white stigmas.
Seed: Female flowers when mature form a dark brown achene, 2 to 2.5 mm long. Florets are wind pollinated. Carex achenes usually require 60 days of cold stratification for germination - or sown outside in the Fall.
Habitat: Sprengel's Sedge grows from short creeping rhizomes which allow vegetative reproduction forming loose colonies. The sedge is found in wet-mesic to dry-mesic woodlands. Grows best in partial sun to full shade. Plants will be less robust in dry conditions.
Names: The genus name, Carex, is from the Latin, being the old name for Sedges. The species, sprengelii, is an honorary for Kurt Polykarp Joachim Sprengel. The name of the authors for the plant classification are as follows: ‘Dewey’ refers to Chester Dewey (1784-1867), American botanist and educator, professor at Williams College and later The University of Rochester. His work in botany is known chiefly for his studies of carices - the Sedges - resulting in a 43 year series of papers titled Caricography. He work was recognized but added to in 1826 by ‘Spreng.’ which is Kurt Polycarp Joachim Sprengel (1766-1833) German botanist who is noted for his early studies of the fertilization of flowers by insects.
Comparisons: Sprengel's Sedge is a member of the section Hymenochlaenae, the characteristics of which are short-rhizomatous root systems, vegetative and flowering stems, sheath fronts hyaline, either white or brownish, blades M shaped; racemose inflorescences with 3 to 7 spikes, upper spikes androgynous, terminal spike staminate or gynecandrous and rarely androgynous; perigynia erect to ascending with 2 strong marginal veins, usually beaked, 3 stigmas; achenes somewhat 3-sided. Of the sedges in this section C. sprengelii is best recognized with the perigynium abruptly narrowed to a beak as long as the body and by the fibrous basal sheaths. No other species in the section has those two characteristics.
Above: A lateral pistillate spike below the upper staminate spikes. 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: The perigynia with beaks as long as the body. The leaf has finely rough edges and a V shape due to the center rig. The sheath area of upper ligules can be hyaline. 3rd photo - the rhizomatous root system.
Below: Basal sheaths have short leaves and (2nd photo) ligules on lower stem are not necessarily hyaline. 3rd photo - the sheath area of the lowest bract.
Below: 1st photo - The terminal spike is usually all staminate with staminate or androgynous spikes below. 2nd photo - below the staminate are pistillate spikes.
Below: Staminate and pistillate spikes at flowering time.
Below: The mature perigynia. Note the prominent marginal rib.
Below: The inflorescence with terminal staminate spike, a lateral staminate spike and below pistillate spikes drooping on long stalks.
Sprengel's Sedge is one of over 150 sedges native to Minnesota. It is widespread in Minnesota, with only 4 counties not reporting it in the DNR surveys. In North America it is found in the parts of the continent with milder summers - all the lower Canadian Provinces except Labrador and Newfoundland and in the U.S. states of the Rocky Mountain area down through NM and then the northern tier of states to the east coast, south as far as Nebraska, Missouri, Illinois, Indiana, Ohio, Pennsylvania and New Jersey.
It has been noted in the Garden since the 1986 Garden Plant 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"