Side Oats Grama
Grass family (Poaceae)
Description: This native perennial grass is about 22½' tall and unbranched. The culms are light green, glabrous, and terete (round in cross-section); later during the fall, they become light tan. The alternate leaves are more common toward the base of each culm. The leaf blades are up to 8" long and ¼" across; they are light green to green, mostly hairless, and rough along their margins. However, toward the base of each leaf blade, there is often a few white hairs that are somewhat deciduous. The larger leaf blades often have prominent central veins. The leaf sheaths are light green, finely ribbed, and hairless. Each ligule has a ring of short fine hairs. The nodes are slightly swollen, rough, and often reddish or brownish green; the portion of the culm near each node may be tinted similarly as well. The culm terminates in a narrow raceme up to 10" long that consists of 30-50 pendulous spikes. Each spike is about ½" long and consists of about 5 spikelets. Each spikelet consists of a pair of linear-lanceolate glumes and a pair of linear-lanceolate lemmas; only one of the lemmas is fertile. The spikelets are up to 1/3" long and greenish red while the flowers are blooming, but they later become tan. Each glume tapers into an acute tip, while the tip of each lemma is often notched on either side. The anthers of the fertile lemmas are bright red to brownish red, while their stigmas are white and feathery. The blooming period occurs from mid-summer to early fall. The spikes of the inflorescence persist into the fall, after which they fall to the ground in their entirety (the glumes are non-persistent). Each fertile lemma bears a single grain. The root system has fibrous roots and short rhizomes. Side Oats Grama often forms tight bunches of culms from its rhizomes, although it also occurs as scattered plants. In moist areas where there is little competition, it may form a dense sod.
Cultivation: The preference is full sun and dry conditions. This grass grows readily in various kinds of soil, including those containing clay-loam, loess, gravel, rocky material, and sand. It is quite drought resistant and adapts well to gentle or moderate slopes.
Range & Habitat: Side Oats Grama is locally common in sunny upland areas along the Mississippi and Illinois River; it is absent in SE Illinois and parts of central Illinois, and uncommon to occasional elsewhere (see Distribution Map). Habitats include various kinds of hill prairies, dry upland prairies (including gravel prairies & dolomite prairies), thinly wooded bluffs and barrens, limestone glades, and areas along railroads. This grass is often used in prairie restorations, from which it occasionally escapes into adjacent areas. As a result, Side Oats Grama is becoming more common in some areas of the state.
Faunal Associations: The leafhoppers Flexamia pectinata and Laevicephalus minimus are specialist feeders of Side Oats Grama. Many grasshoppers feed on this prairie grass (see Grasshopper Table), as do the stinkbugs Moromorpha tetra and Mecidea major. Some upland gamebirds and granivorous songbirds are known to feed on the seeds of Bouteloua spp. (Grama Grasses), but information for Side Oats Grama in Illinois is unavailable. In Texas and states of the Great Plains, the McCown Longspur and Wild Turkey eat the seeds of various Grama grasses. Some hoofed mammalian herbivores, including bison, horses, and cattle, graze on Grama grasses readily, including Side Oats Grama.
Photographic Location: A prairie at Meadowbrook Park in Urbana, Illinois.
Comments: Side Oats Grama is the only Bouteloua sp. (Grama Grass) that is fairly common in Illinois. Two other species, Bouteloua gracilis (Blue Grama) and Bouteloua hirsuta (Hairy Grama), are shorter grasses that are more common in states of the Great Plains. These latter two species have curious racemes of spikes that are shaped like eye-lashes; they tend to be held horizontally in relation to the ground. Among the grasses of Illinois, the inflorescence of Side Oats Grama is really quite unique as the spaced out spikes tend to droop on one side of the raceme's central axis. As a result, this interesting grass is easy to identify. Side Oats Grama is a warm-season grass with a C4 metabolism (a trait it shares with other Grama Grasses). This enables it to tolerate the hot dry summers of the Midwest and other areas further to the west.