Prairie Cordgrass is a robust warm-season grass that grows from strong scaly rhizomes that can spread the plant 5 to 10 feet per year which is why it is sometimes found in pure dense stands in the pothole area of the old tall-grass prairie. The stems are erect, tall - reaching to 8 feet - and stout - up to 11 mm thick (about 7/16 inches).
Leaf blades are 3/16 to 5/8 inch wide (5-15 mm) and 8 to 30 inches long, mostly smooth of the lower surface but rough on top with sharp finely serrated edges. The blades have prominent linear veining and taper to a fine tip.
Sheaths and ligules: The leaf sheath has a long open throat with the sheath smooth but the throat is often hairy. Ligules are 1 to 3 mm long.
Inflorescence: The flowering panicles are 12 to 20 inches long and are composed of 5 to 50 (usually 7 to 17) densely flowered raceme-like branches. The branches are comb-like with 10 to 80 spikelets growing in two rows on the side of the spike away (outward) from the stem.
The spikelets have one bisexual floret each, with the glumes having a short barbed awn which causes them to stick to clothing. (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). The glumes are keeled, unequal in size - the lower glume 5 to 10 mm long and shorter than the floret, the upper much longer - 10 - 25 mm long; both can have fine stiff hair on the keels. The lemmas are bilobed. Florets have 3 anthers.
A variegated cultivar is available - 'Aureo-marginata' - with yellow margins and stripes.
Habitat: The seed is said to be poorly viable, thus the spread of the plant is via the vigorous rhizomes. It tolerates moisture very well making it the native grass of choice for wet areas. It is an excellent choice for pond edges or any low, damp area. Cordgrass makes good shelter for birds and animals, but is not useful for animal forage except when young and tender before the blades develop the serrated edges, so farmers will cut the grass early and several times during the growing season.
Names: The scientific names: Spartina is from the Greek spartine, for a cord made from Spartium junceum, and thus a reference to the tough fibers of the leaves which could make cords. The species, pectinata is Latin for "comb-like" referring to the flower panicles. The author names of the plant classification are as follows: First to publish was ‘Bosc’ which refers to Louis Augustin Guillaume Bosc (1759-1828), French botanist and entomologist, at one time French consul in the U.S., author of several botanical works and in 1825 became chair of plant culture at the Natural Museum of Natural History in Paris. His work was incomplete and amended by ‘Link’ who was Johann Heinrich Friedrich Link (1767-1851) German naturalist and botanist who succeeded Willdenow as director and curator of the Botanic Garden of Berlin, published widely and named many species.
Comparisons: One other species of Spartina grows in Minnesota - S. gracilis, Alkali Cordgrass. It is a much shorter grass, growing only to 3.5 feet and thin stems - 2 to 3.5 mm. The panicle has only 3 to 12 branches with 10 to 30 spikelets per branch. It is found in only a few counties of the State bordering the Dakotas. See comparison drawing below.
Above: Tall stems of Prairie Cordgrass, photo ©Phoebe Waugh. Drawing courtesy USDA-NRCS PLANTS Database / Hitchcock, A.S. (rev. A. Chase). 1950. Manual of the grasses of the United States.
Below: 1st photo - The beginning of a flower panicle. 2nd photo - A fully developed flower panicle with florets in flower.
Below: Detail of the spikelets while in flower, forming a double row on the panicle branch and facing away from the stem.
Below: Parts of a mature panicle branch - note the barbed edges on the larger upper glumes and the awns.
Below: 1st & 2nd photos - The leaf sheath has a long open throat and is often hairy. 3rd & 4th photos - Note the veining in the leaf blade and the very finely serrated edge of the blade
Below: Floret detail - ©Anna Gardner, University of Iowa. Comparative Drawing showing the two Spartina species native to Minnesota (S. gracilis and S. pectinata) by Linda A. Vorobik and Linda Bea Miller, ©Utah State University.
Prairie Cordgrass is a native perennial found throughout the United States except the far SW Corner and the SE Corner, and in all the lower Canadian Provinces except British Columbia. In Minnesota it is found in almost all the counties except Cook and a few in the north central part of the state.
Nine species of Spartina are native to North America along with two introduced species and three hybrids. There are 15 to 17 known species worldwide.
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"