IUCN threat status:

Not evaluated

Comprehensive Description

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Description

This native perennial grass is 3-8' tall, more or less erect, and unbranched or little branched. Each culm is terete, tan, and hairless; its nodes are dark-colored, slightly swollen, and glaucous. There are several alternate leaves that become smaller as they ascend the culm. The leaf blades are up to 1½' long and ½" across; they are dull green to glaucous blue, linear in shape, mostly hairless, and rather floppy. The leaf sheaths wrap tightly around the culms; they are dull green to glaucous blue, and mostly hairless. Sometimes there are short hairs near the ligules. Each culm terminates in 2-6 narrow racemes of spikelets. These racemes originate near the base of the inflorescence and spread outward, forming a claw-like V-shape. Each raceme is up to 6" long. The spikelets occur in pairs along the raceme; they are appressed against the central axis of each raceme, or they are slightly spreading. One spikelet in a pair is sessile and perfect, while the other spikelet is pedicellate and staminate. The pedicels of the latter spikelets are covered with short fine hairs. Both kinds of spikelets are up to 1/3" (10 mm.) in length and similar in size; they have narrowly lanceolate glumes. The fertile lemma of the sessile spikelet has a straight awn up to ½" long. The spikelets are dull greyish green to purplish red in color; their anthers are yellow to dull red. The blooming period occurs during late summer or early fall. Pollination is by wind. Each spikelet produces a single grain. The root system is fibrous and produces short rhizomes. Big Bluestem is a bunchgrass as tight tufts of culms are produced from these rhizomes.

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© John Hilty

Source: Illinois Wildflowers

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