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Comprehensive Description

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During the late spring and summer, this native perennial grass is tufted at the base, producing unbranched culms about 3-5' tall. Each culm has about 8 alternate leaves that are distributed throughout its length; the lower leaves often become withered before commencement of the blooming period. From fall to spring, this grass produces clumps of low basal leaves up to 1' tall that are semi-evergreen. Each culm is light green, terete, and slightly glaucous; it is mostly hidden by the sheaths. The blades of the alternate leaves are up to 13" long and 2/3" (15 mm.) across; they are ascending to spreading, hairless, and widest toward the middle. The upper surface of each blade is green, while the lower surface is blue and glaucous. The sheaths of the alternate leaves are mostly blue and glaucous, although the lower sheaths may be somewhat green; they are hairless, open, and longer than than the internodal areas of the culm. Each ligule consists of a stiff short membrane that soon turns brown. The nodes of the culm are slightly swollen. Each culm terminates in a nodding spike about 5-9" long and 1½" across. This spike consists of a dense arrangement of slightly spreading spikelets and their awns; it has a blue and a glaucous appearance. Each spikelet has a pair of glumes below and 3-6 lemmas above, forming a V-shape; the spikelets occur in groups of 2 or more. Each glume is about 2.0–2.5 cm. long (including its awn) and 1.25 mm. across; it is blue-glaucous, linear in shape, and slightly ciliate along the margins with short stiff hairs. Each lemma is about 1.0–1.5 cm. long (excluding its awn), 2.25 mm. across, and having an awn about 2.0–4.0 cm. long; it is blue-glaucous, finely pubescent on the outer surface, and narrowly linear-lanceolate in shape. Each lemma encloses a palea (a membrane that surrounds the ovary/grain) that is 8.5–13.0 mm. in length. The blooming period occurs during mid- to late summer. The culms and their spikes turn tan during the fall, at which time the awns curve outward. Disarticulation of the spikelets is above the glumes. The large grains are 5.0–7.0 mm. long, 1.5–2.0 mm. across, somewhat flattened, and narrowly oblongoid-ellipsoid in shape. The root system is fibrous.


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

© John Hilty

Source: Illinois Wildflowers

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