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1 Internodes glabrous (sometimes lowest internodes sparsely to moderately pubescent). |
2 Ligule 1-2 mm long; sheaths sparsely to moderately spreading short- pilose; nodes retrorsely bearded; leaves 1-4 cm long, 2-5 mm wide; spikelets 1.2-1.4 mm long |
 Show caption*© Janet Wright, some rights reserved (CC BY-NC), uploaded by Janet Wright (1.5-) 2-5 mm long; sheaths glabrous to variously pubescent, but not spreading short- pilose; nodes glabrous or pubescent, but not bearded; leaves 4-11 cm long, 4-8 mm wide. |
3 Leaf blade basal cilia usually conspicuous; larger vernal blades 6-10 cm by 6-10 mm; internodes, especially lower, sometimes pilose; spikelets obovoid; plant often yellowish-green (orange-brown in age) |
3 Leaf blade basal cilia usually inconspicuous or absent; larger vernal blades 2.5-10 cm long, 2-9 mm wide; all internodes glabrous (rarely the lowest sparsely pilose); spikelets ellipsoid; plant often green to purplish. |
4 Spikelets (0.9-) 1.1-1.5 mm long, moderately densely to densely puberulent, most hairs < 0.1 mm long; panicles 3-8 cm long, usually more than ½ as wide as long; larger blades 2.5-8 cm long |
4 Spikelets (1.3-) 1.4-1.9 mm long, ( glabrous-) sparsely to moderately pubescent, most hairs > 0.1 mm long; panicles 4-12 cm long, usually less than ½ as wide as long; larger blades 7-10 cm long |
1 Internodes variously pubescent. |
5 Peduncle, panicle axis, and/or sheaths of vernal culms puberulent with hairs 0.1 mm long, sometimes also pubescent with longer hairs, but never grayish- villous; larger leaf blades 2-7 cm long, 2-7 mm wide. |
6 Spikelets 0.8-1.1 mm long; mid- culm leaf blades 2-4.5 cm long, 2-5 mm wide; sheaths sparsely puberulent to glabrous, lacking papillose-based longer hairs |
6 Spikelets 1.1-1.7 mm long; mid- culm leaf blades generally 3-7 cm long and 3-7 mm wide; sheaths with some papillose-based hairs 2 mm or more long. |
7 Larger mid- culm leaf blades 4-7 cm long, 4-7 mm wide, glabrous to sparsely pubescent adaxially; ligule 1-5 mm long; spikelets 1.1-1.5 mm long |
7 Larger mid- culm leaf blades 3-6 cm long, 3-5 mm wide, long- pilose adaxially; ligule often with a ring of hairs < 1 mm and scattered longer hairs to 4 mm; spikelets 1.3-1.7 mm long |
5 Peduncle, panicle axis, and sheaths of vernal culms glabrous, or pilose, or grayish- villous with some shorter hairs 0.2-0.5 mm long, but not puberulent with hairs 0.1 mm long; larger blades 4-20 cm long, 4-12 mm wide. |
8 Culms > 100 cm long; node pubescence densely retrorse; larger blades 12-20 cm long, 15-20 × as long as wide; spikelets 1.9-2.3 mm long, 2× or more as long as wide, acute |
8 Culms < 100 cm long (-rarely longer); node pubescence various; larger blades 4-12 cm long, < 15 × as long as wide; spikelets (1.0-) 1.1-2.0 mm long, less than 2× as long as wide, rounded to blunt. |
9 Sheaths and internodes of vernal culms gray- villous with a dense, tangled, or matted mixture of slender hairs 2-4 mm long, variously ascending, spreading, and retrorse, papillose or non- papillose, often with shorter hairs beneath; leaf blades velvety- pubescent on abaxial surface, the margins ciliate (or appearing ciliate) for half or more their length. |
10 Plants drying light green to yellow-green; culms usually < 60 cm long; lower internodes rarely more than 1.3 mm in diameter; panicles usually < 8 cm long; primary branching at most nodes before maturation of vernal panicle, longer branches often exceeding the culm |
10 Plants drying olive-green, sometimes purplish; culms usually > 60 cm long; lower internodes usually > 2 mm in diameter; panicles usually 9-11 cm long; primary branching sparingly from middle nodes after maturation of vernal panicle, longer branches not exceeding culm |
9 Sheaths and internodes of vernal culms puberulent, pubescent or papillose- pilose to hispid with ascending straight hairs, but never grayish- villous; leaf blades glabrous to variously pilose abaxially, but not velvety- pubescent, the margins eciliate or ciliate only below the middle. |
11 Spikelets 0.8-1.1 mm long; blades 2-4.5 cm long, 2-5 mm wide |
11 Spikelets 1.1-2.0 mm long; blades 3-12 cm long, 3-12 mm wide. |
12 Peduncle, panicle axis, and often middle and upper internodes glabrous; sheaths lacking hairs or papillae, at least near mid-length |
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13 Leaf blades 5-12 cm long, 6-12 mm wide; spikelets 1.5-2.0 mm long; peduncle, panicle axis, and sheaths variously pilose, but lacking puberulent hairs 0.1 mm long |
13 Leaf blades 3-7 cm long, 3-7 mm wide; spikelets 1.1-1.7 mm long; puberulent hairs 0.1 mm long often present on peduncle, panicle axis, or sheaths. |
14 Larger mid- culm leaf blades 4-7 cm long, 4-7 mm wide, glabrous to sparsely pubescent adaxially; ligule 1-5 mm long, the hairs of one series; spikelets 1.1-1.5 mm long |
14 Larger mid- culm leaf blades 3-6 cm long, 3-5 mm wide, long- pilose adaxially; ligule often with a short series of hairs <1 mm long in front of a series with hairs to 4 mm long; spikelets 1.3-1.7 mm long |