This is a form of the species which Fassett recognizes but Hitchcock does not. It seems to be distinct in our area. Its habitat is that of the species.

Stems 1-3 m (in water seldom over 6 dm deep); lvs 1-3 cm wide; ligule 10-15 mm; panicle wider and more ample, the lower branches with usually 26-50 staminate spikelets; awns of the pistillate lemmas 4-7 cm. Ind. to Mo. and Nebr., n. to N.D. and se. Man. (Z. interior; Z. aquatica var. i.)

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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