Grass family (Poaceae)
Description: This native perennial grass is about 4-7' tall and unbranched. The central culm is green to light brown, terete (round in cross-section), and glabrous. The alternate leaves are located primarily along the lower half of the culm. The leaf blades are up to 3' long and 1" across; they are linear, flat, green to yellowish green, and glabrous. Each blade has a rather thick succulent texture, fine parallel veins, and a prominent midrib. The leaf blades typically curve upward from the central culm and then curve downward toward their tips. The leaf sheaths are green to yellowish green, finely ribbed, and glabrous. Each ligule at the junction of the blade and sheath has a ring of dense white hairs. The culm terminates in a raceme of floral spikes up to 1½' long; these spikes are widely spaced along the central stalk of the raceme and they are appressed, ascending, or widely spreading. Each spike is about 3-5" long and consists of many narrow spikelets that are densely appressed together along one side of its rachilla (secondary stalk). At the base of each spike, there is a pedicel up to 1" long, while the rachilla of the spike is often dark red or burgundy. The spikelets are initially green and glabrous, although they later turn brown after the blooming period. Each spikelet consists of a pair of glumes, a pair of lemmas, and a floret. The first glume is about 1/3" (10 mm.) long, linear-lanceolate, and strongly keeled; the second glume is 2/31" (20-30 mm.) long (including its awn), linear-lanceolate, strongly keeled, and conspicuously awned. The keels of the glumes have rough margins. The lemmas are about 1/3" (10 mm.) in length, linear-lanceolate, and keeled. Each floret has 3 stamens and 2 plumose stigmas. The blooming period occurs from mid-summer to early fall. With maturity, the spikelets disarticulate below the glumes and fall to the ground with their grains. The root system is fibrous and strongly rhizomatous. Vegetative colonies of plants are often produced.
Cultivation: The preference is full to partial sun, wet to mesic conditions, and a fertile loamy soil to sustain the prodigious growth of this grass. It also adapts to soil that is rocky or sandy if consistent moisture is maintained. This grass is somewhat aggressive, although it won't tolerate regular mowing.
Range & Habitat: Prairie Cordgrass is occasional to locally common in central and northern Illinois, while in southern Illinois it is occasional or absent (see Distribution Map). Habitats include openings in floodplain forests, wet to moist prairies (including black soil, sand, & dolomite), prairie swales and sloughs, low areas along rivers and ponds, edges of marshes, swamps, roadside ditches, low areas along railroads, edges of fields, and soggy vacant lots. This grass is often found in moist prairie remnants and can survive low to moderate levels of degradation because of its robust nature. It also survives occasional droughts rather well because of its C4 metabolism.
Faunal Associations: Several moth species are oligoleges (specialist feeders) of Prairie Cordgrass. This includes Luperina stipata (Noctuid Moth sp.), Chortodes enervata (Many-Lined Cordgrass Moth), Spartiniphaga inops (Noctuid Moth sp.), and Peoria gemmatella (Gemmed Cordgrass Borer Moth). Other specialist insect feeders include the leafhoppers Destria fumidus and Neohecalus magnificus. The rootstocks and seedheads of Prairie Cordgrass are eaten by the Canada Goose. The seedheads are occasionally eaten by the Black Duck, Mallards, and other ducks. Muskrats feed on the rootstocks and foliage. Because Prairie Cordgrass forms dense colonies of tall vegetation, it is an important source of protective cover and nesting habitat for many wetland birds and other kinds of wildlife.
Photographic Location: The Red Bison Railroad Prairie in Savoy, Illinois, where this grass occurs in wet to mesic locations.
Comments: Prairie Cordgrass has attractive foliage with a succulent appearance. It was the dominant grass of wet prairies in Illinois and no other grass species in the state resembles it. There are similar Spartina spp. (Cordgrasses) in brackish and saltwater marshes along both the Eastern and Gulf coasts, but they don't occur in Illinois. Prairie Cordgrass can be distinguished from these species by the long awns of its second glumes (about 1/32/3" in length) and the relative length of its first glumes, which are about the same length as the lemmas (1/3" in length). Other Cordgrasses lack these long awns and their first glumes are shorter than their lemmas.