1. Lateral awns < 12 mm long, < half as long and half as thick as central awn (this to 30 mm long)â€?a href="Ar_patula.html">A. patula
1. Lateral awns 10 or more mm, > half the length of the central awnâ€?
2. Inflorescence a dense foxtail > 15 mm wide (excluding awns) wideâ€?a href="Ar_spiciformis.html">A. spiciformis
2. Inflorescence otherwiseâ€?
3. Wetland grass with well developed scaly rhizome; upper glume with awn > (3)-7 mmâ€?a href="Ar_rhizomphora.html">A. rhizomophora (basal sheath shredding) (central awn 15-30 mm long, horizontal to reflexed; lateral awn 13-20 mm)
3. Wetland or dry habitat grass without strongly developed rhizome; upper glume with no awn or with awn < 3 mm longâ€?
4. Leaf blades predominantly flat toward the base of the plantâ€?
4. Leaf blades involuteâ€?
5. Leaf blades curled; lower glume < 9 mm long; ligule < 0.1 mm long; central awn 8-25 mmâ€?a href="Ar_purpurascens.html">A. purpurascens
5. Leaf blades usually not curled; lower glume > 9 mm long; ligule 0.2 mm long; central awn 15-40 mm longâ€?a href="Ar_palustris.html">A palustris
6. Awns contorted (also true in A. purpurascens var. tenuispica with flat leaves and equal glumes); glumes unequal; callus usually > 1 mm long; leaf collars glabrous; awns nearly equalâ€?a href="Ar_gyrans.html">A. gyrans
6. Awns not contorted; glumes nearly equal; callus usually 0.4-0.6 mm; leaf collars pubescent; lateral awns a little shorter than central awnâ€?a href="Ar_stricta.html">A. stricta