Grass family (Poaceae)
Description: This native perennial grass is 12½' long, branching occasionally. The slender culms of this grass are initially erect, but they have a tendency to sprawl later in the year. Each culm is light green to pale purple (less often bright red), terete, and glabrous. The leaf blades are up to 3½" long and ¼" across; they are medium to greyish green, hairless, and spreading to ascending along the culms. The upper surface of each leaf often has a central vein and 2 lateral veins that are conspicuous; otherwise, its surface is rather flat. The leaf sheaths are light green to medium green, finely veined, and hairless; they are rather short and expose the culms at intervals. The lower ligules are swollen, glabrous, and pale green to reddish green; the upper ligules are more dark and sunken in appearance. The upper culms terminate in elongated panicles of spikelets about 4-10" long. These panicles have short erect branches (up to 2" long) and a spike-like appearance; they are greyish green or purplish green and silky in appearance during the period of bloom. Each spikelet is about 2 mm. long (excluding the awn) and narrowly lanceolate; it consists of 2 tiny glumes, a single awned lemma, and a membranous palea enclosing the floret. The lemma is long as the spikelet (2 mm.) and it has a slender awn that is 24 mm. in length. The blooming period occurs from mid-summer to early fall. Pollination is by wind. The spikelets disarticulate above their tiny glumes and fall to the ground. The tiny dark seeds are small enough to be dispersed by the wind. The root system is fibrous. This grass can reproduce vegetatively by forming rootlets along the lower nodes of the culms. Even though it doesn't have rhizomes, this grass often forms colonies.
Cultivation: The preference is light shade to partial sun, moist to mesic conditions, and a rich loamy soil. It also adapts to a somewhat acid soil that is sandy or rocky.
Range & Habitat: Nimblewill is occasional to locally common throughout Illinois (see Distribution Map). Habitats include thin or low woodlands (whether deciduous or coniferous), sandy woodlands, sandstone glades and rocky slopes, thickets, woodland edges, areas along woodland paths (if the soil is not too compacted), powerline clearances in wooded areas, degraded meadows, fence rows, grassy areas near back alleys in cities, partially shaded areas of lawns, and waste areas. This native grass prefers habitats with a history of disturbance, although it is sometimes found in higher quality habitats. Occasionally, it becomes a lawn weed, particularly in northern Illinois.
Faunal Associations: The plant bug Stenodema vicinum feeds on Muhlenbergia spp. (Satin Grasses). The tiny seeds of Nimblewill are too small to be useful as a food source for birds. The young foliage of Nimblewill is palatable and readily eaten by cattle and other hoofed herbivores. When the ground is moist, the tiny seeds may cling to the feet of animals and the shoes of humans, distributing this grass to new areas.
Photographic Location: Along a woodland path at Busey Woods in Urbana, Illinois.
Comments: This delicate grass blends into the background readily. Among the various Muhlenbergia spp. (Satin Grasses), Nimblewill is the one that you are most likely to encounter in suburban and urban areas; it has low fidelity to any particular habitat and can appear almost anywhere that is sufficiently moist and receives a little shade. Most Satin Grasses are more robust in appearance than Nimblewill and they have more stout inflorescences; their spikelets frequently lack awns. An exception is Muhlenbergia sylvatica (Woodland Muhly), which has awns that are somewhat longer than those of Nimblewill. However, Woodland Muhly has conspicuous glumes that are almost as long as its spikelets, while the glumes of Nimblewill are tiny and inconspicuous (in fact, it has the smallest glumes of any Muhlenbergia sp. in Illinois).