Comprehensive Description

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This introduced grass is about 2-3' tall and unbranched, although it may tiller at the base and send up multiple culms. The culms are green, terete, and glabrous. Along each culm, there are 3-5 alternate leaves. The leaf blades are up to 10" long and 10 mm. across; they are ascending or slightly arching and somewhat stiff. The upper blade surface is grayish blue, hairless to sparsely short-pubescent, and slightly rough-textured, while the lower blade surface is medium green, hairless, and more smooth-textured. At the base of each leaf blade, there is a pair of slender auricles (ear-like lobes) that wrap around the culm. The leaf sheaths are dull green and either hairless or short-pubescent. The ligules are short-membranous. The culm terminates in a spike-like raceme up to 8" long that is stiff and erect. Along this raceme are spikelets up to 20 mm. long that alternate along each side of its rachis on short peduncles; these spikelets are appressed-erect to strongly ascending. Immature spikelets are dull green to grayish blue, while mature spikelets are light brown or stramineous (straw-colored). Each spikelet consists of a pair of glumes at the bottom and 3-7 florets with their lemmas above. In each spikelet, the lemmas are arranged into 2 overlapping ranks. The glumes are about 8-11 mm. long and linear-lanceolate in shape; they have several fine longitudinal veins along their convex outer surfaces. The tips of glumes are acute and awnless. The lemmas are about 8-11 mm. long (excluding any awns) and linear to linear-lanceolate in shape; they have several fine longitudinal veins along their convex outer surfaces. The typical form of Quack Grass (f. repens) has either awnless lemmas or lemmas with awns up to 2 mm. in length, while f. aristata has lemmas with awns up to 10 mm. in length. The blooming period occurs during the summer, lasting about 1-2 weeks. The florets of the spikelets are cross-pollinated by the wind. Upon maturity, each spikelet easily detaches from its base and falls in its entirety to the ground; the individual glumes and lemmas do not separate as readily from each other. Individual grains are about 5 mm. in length, light tan, ellipsoid-oblongoid in shape, and slightly flattened. The root system is fibrous and long-rhizomatous. Clonal colonies of plants often develop from the rhizomes. Cultivation


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© John Hilty

Source: Illinois Wildflowers

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