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. Oval-leaf Sedge is a perennial tufted sedge commonly found in fields and dry woods. The flowering stems (culms) grow 8 to 24 inches high, erect, unbranched with smooth surface except the upper areas may be rough to the touch. Stems narrow in width from 2 to 3.5 mm wide below to 0.5 to 1 mm wide near the top. Roots may put up multiple stems. Basal areas are purplish.
The basal leaf sheaths do not have prominent cross-veins. Upper leaf sheaths are tight and green with fronts that have somewhat translucent edges, but no other coloring. Ligules are longer than wide.
The upper leaf blades are only 2.5 to 5.5 mm wide, and up to 8 inches long, V shaped when young otherwise flat, smooth but the edges may be rough on some plants.
The inflorescence is dense with all the spikes crowded into what looks like a single conical head. They consist of 3 to 8 un-stalked spikes, each spike from 0.6 to 2 cm long and 5 to 10 mm wide. In this species, the spikes are individually indistinct, hence the crowded look. The terminal spike is androgynous, that is, with both staminate and pistillate florets, the staminate at the tip, the pistillate below. The closely spaced lateral spikes may be androgynous but are usually all pistillate. Each spike can have 4 to 20 ascending to spreading perigynia. (The bladder-like sacs that enclose the female flower and later the fruit are called perigynia, singular - perigynium).
Perigynia: Each perigynium is green to pale yellow in color, vein-less or weakly 8-veined, without hair, flattened on one face, otherwise rounded, (elliptic to circular) broadest at or just below the middle, roughly 2.5 to 3.2 mm long and 1.4 to 2 mm wide. There is a beak 0.7 to 1.1 mm long, with rough margins and 2 tiny teeth. The bracts that form at the base of the spikes are thread-like, stiff, and usually shorter than or no more than 2x the length of the inflorescence itself. The lowest bract is either without a sheath or with one no more than 4 mm long. The scales of the pistillate perigynia have a translucent appearance with a green mid-vein; these are ovate and not more than 1/2 the length of the perigynia and narrower with a slender tip. Scales turn to a light brown at maturity. There are two stigmas per pistillate floret and three stamens per staminate floret.
Seed: Mature fruit is a brown circular shaped achene, about 1 x 1 mm, with a short beak at the tip. Florets are wind pollinated. Carex achenes usually require 60 days of cold stratification for germination - or sown outside in the Fall.
Habitat: Oval-leaf Sedge grows from a short knotty brown rootstock without conspicuous rhizomes, forming clumps in dry to wet-mesic deciduous forests, thickets, wood-edges where there is partial shade. It can tolerate full sun and thus invade fields and lawns.
Names: The genus name, Carex, is from the Latin, being the old name for Sedges. The species, cephalophora, is derived from the Greek kephale, meaning 'head' and phoros, meaning to 'carry', referring to the spikelets all being carried at the tip of the stem. The author names for the plant classifications 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. While the most accepted common name of this species by international and Minnesota authorities is Oval-leaf Sedge, the alternate common name of Woodbank Sedge is representative of where the plant is found.
Comparisons: Oval-leaf Sedge is a member of the short-headed bracted sedges in the Section Phaestoglochin, and has the distinguishing characteristics of clustered androgynous spikes containing ascending to spreading perigynia with scales no more that half the length of the perigynia. Other sedges like this with dense spikes include C. leavenworthii, where the perigynia are more ovate with a shorter beak or C. mesochorea where the head is more globose rather than elongated. Neither are in the Minnesota area.
Above: The spikelets are all crowded together in a dense head, with subtending bracts thread-like. 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: Young leaves have a V shape due to the central vein ridge. The various spikelets are not stalked and packed next to each other on the stem. The mature perigynia is brown, weakly 8-veined, flattened on one side, otherwise rounded, with a two-toothed beak. Perigynium photo ©Linda W. Curtis, University of Wisconsin, Steven's Point.
Below: 1st photo - the base of the stems. 2nd & 3rd photos - the leaf sheath front and back
Oval-leaf Sedge is one of over 150 sedges native to Minnesota. It is not widespread in the state with only 22 counties reporting it. Most of those counties are in and surround the metro area and south-southeast. In North America it is found from the Great Plains eastward in the U.S. and in Ontario and Quebec in Canada.
It has been noted in the Garden on both the 1986 and 2009 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"