Comprehensive Description

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This grass is a short-lived perennial that produces either a solitary culm or small tuft of leafy culms about ¾–2' tall. Both fertile and shorter infertile shoots are present. The culms are light green, hairless, and terete to slightly compressed (subterete). On each fertile culm, the leaves mostly occur along the lower one-third of its length, where they are alternate. The leaf blades are 2-5 mm. across and up to 6" long; they are medium to dark green, hairless, and ascending to widely spreading. The leaf blades are furrowed above and keeled below; they have whitened auricles (ear-like basal lobes) at their bases that clasp the culms. The leaf sheaths wrap tightly around their culms; they are medium green, hairless, and open. However, the lowermost sheaths may become tan to reddish brown and disintegrate with age. The ligules are short-membranous, while the nodes are swollen and glabrous. Each fertile culm terminates in a flowering spike about 4-10" long. This spike consists of several sessile spikelets that alternate along two sides of the rachis (central stalk of the spike). The rachis is slightly indented where each spikelet occurs, providing it with a curvilinear zigzag appearance.  Each non-terminal spikelet is 8-16 mm. in length, consisting of a single outer glume at its base and 4-10 lemmas that are arranged in 2 overlapping ranks. The lemmas are 4-7 mm. in length, oblong in shape, convex along their outer surfaces, longitudinally veined, and hairless. The floret of each fertile lemma consists of an ovary, a pair of feathery stigmata, and 3 stamens. The outer glume is longer than individual lemmas, but shorter than the spikelet. Aside from its greater length, the glume is similar in appearance to the lemmas. Terminal spikelets are the same as non-terminal spikelets, except they have 2 glumes; these glumes are similar to the outer glumes of the non-terminal spikelets. As the spikelets mature, they change in color from light green to light tan. The blooming period typically occurs during early summer, although this may be delayed by disturbance. The florets are cross-pollinated by the wind. Afterwards, the florets of fertile lemmas are replaced by grains. At maturity, these grains are 3-5.5 mm. long, narrowly oblongoid in shape, narrowly grooved along one side, and light tan. Disarticulation of the spikelets is above the glumes. The root system consists of a tuft of shallow fibrous roots. This grass reproduces by reseeding itself. Cultivation


Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© John Hilty

Source: Illinois Wildflowers

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