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1 Ligule with a dense ring of short hairs 0.5-1 mm long, and behind it a ring of longer hairs 1-5 mm long called the pseudoligule (see introduction for discussion of the so-called double ligule). |
2 Culms > 100 cm long; node pubescence densely retrorse; larger blades 12-20 cm long; spikelets acute, 1.9-2.3 mm long, 2× or more as long as wide |
2 Culms < 100 cm long (rarely longer); node pubescence various; larger blades 3-12 cm long; spikelets rounded to blunt, (1.0-) 1.1-2.0 mm long, less than 2 × as long as wide. |
3 Plants velvety- pubescent throughout; nodes retrorsely bearded; internode pubescence retrorse to spreading; blades usually ciliate above base as well as basally; mature vernal panicles 3-7 cm long, 2-5 cm wide, about 2/3 as wide as long |
3 Plants densely pubescent to glabrate, but lacking velvety pubescence; nodes with spreading to ascending pubescence (sometimes retrorse in D. villosissimum); internode pubescence ascending, appressed, or spreading; blades ciliate only at base (sometimes appearing ciliate laterally in D. ovale var. ovale); mature vernal panicles 4-10 cm long, nearly or equally as wide. |
4 Lower internodes with retrorse or spreading hairs to 3+ mm long; blade adaxial surface pilose with hairs to 4+ mm long, these appressed and angled away from the leaf axis; spikelets 2.1-2.5 mm long |
4 Lower internodes pilose with (spreading-) ascending to appressed hairs, or nearly glabrous; blade adaxial surface sparsely appressed- pubescent to glabrate; spikelets 2.1-3.1 mm long. |
5 Spikelets 2.1-2.6 mm long; lower culm blades usually sparsely appressed- pubescent on both surfaces, eciliate or ciliate at the base only |
5 Spikelets 2.5-3.1 mm long; lower culm blades usually glabrous adaxially except for long hairs at or near the margin (appearing ciliate), appressed- pubescent abaxially |
1 Ligule a single structure, without a pseudoligule. |
6 Ligule 2-5 mm long, ciliate |
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7 Ligule a stramineous to light brown membrane, with or without terminal cilia; peduncle antrorsely scabrous but not hairy. |
8 Panicle rachis smooth, pellucid- punctate; first glume 0.3-0.6 (-0.8 ) mm long, as broad as or broader than long, truncate to obtuse; larger leaves 10-25 cm long, 8-15 mm wide; ligule 0.5-1.3 mm long; lowest elongate culm internode > 2 mm in diameter; lowest nodes usually glabrous or pubescent |
8 Panicle rachis scabrous or smooth, not pellucid- punctate; first glume 0.5-1.1 mm long, longer than wide, rounded to acute; larger leaves 3.5-12 cm long, 3-9 mm wide; ligule 0.1-0.6 mm long; lowest elongate culm internode < 2 mm in diameter; lowest nodes retrorsely bearded or glabrous. |
9 Lowest nodes usually retrorsely bearded; ligules (0.1-) 0.3-0.6 mm long; largest vernal blades 7-12 cm long, (4.5-) 6-9 mm wide; panicle peduncle scabrous; spikelets ovate- lanceolate, acute, 2.0-2.4 mm long; first glume lanceolate, blunt to acute; fertile lemma smooth |
9 Lowest nodes usually glabrous; ligules 0.1-0.2 (-0.3) mm long; largest vernal blades 3.5-7 cm long, 3-6 mm wide; panicle peduncle smooth; spikelets elliptic, blunt to acute, 1.6-2.2 mm long; first glume ovate to rotund, rounded to acute; fertile lemma papillose |
7 Ligule entirely of white hairs; peduncle variously hairy or glabrous, but not antrorsely scabrous. |
10 Culms with a viscid band below the retrorsely bearded nodes; internodes, sheaths, and blades velvety- pubescent |
10 Culms without a viscid band below the retrorsely, spreading, or antrorsely bearded nodes; internodes and sheaths not velvety- pubescent, blades velvety- pubescent in some. |
11 Basal as well as cauline blades linear, 5-15 cm long,; 1-4 mm wide, 30× or more as long as wide; spikelets 2.8-3.8 (-4.5) mm long |
11 Blades < 15× as long as wide (if > 15×, then spikelets 1.9-2.5 mm long and sheaths retrorsely pilose in D. laxiflorum). |
12 Blades (15-) 20× or more as long as wide, increasing in length upwards on culm; blade adaxial surface (weakly-) strongly scabrous; sheaths glabrous; second glume and sterile lemma exceeding fertile lemma |
12 Blades < 15× as long as wide, similar or more often decreasing in size upwards on culm (if increasing, then sheaths strongly retrorsely pilose in D. laxiflorum); blade adaxial surface smooth to moderately scabrous; second glume and sterile lemma shorter than to exceeding fertile lemma. |
13 Nodes retrorsely bearded; larger vernal leaves 7-15 mm wide. |
14 Sheaths retrorsely pilose with hairs 2-3 mm long; basal leaves usually numerous, ascending, similar in size and shape to the culm leaves; culms branching only at the base in autumnal phase |
14 Sheaths glabrous or pilose (if pilose, then hairs not both retrorse and 2-3 mm long); basal leaves rosette-forming, usually much shorter than culm leaves; culms branching above base in autumnal phase. |
15 Plants rarely > 1 m in length; lower internodes glabrous to sparsely hairy; vernal cauline leaves 3-7; spikelets 1.8-2.8 mm long, elliptic to lance- ovate, blunt to acute, glabrous or pubescent |
15 Plants often > 1 m in length; lowest internodes moderately to densely villous; vernal cauline leaves 6-15; spikelets 1.8-2.2 mm long, obovoid to broadly ellipsoid, rounded to blunt, pubescent |
13 Nodes spreading to antrorsely bearded; larger vernal leaves 3-10 mm wide. |
16 Culm internodes glabrous to sparsely pilose; culm nodes bearded with long retrorse hairs; blade surfaces glabrous to velvety- pubescent |
16 Culm internodes, at least the lower, strigose, pilose, or villous; culm nodes bearded with ascending or spreading hairs; blade surfaces glabrous or variously hairy. |
17 Lower nodes bearded with erect- ascending, soft, and long hairs; mid- culm blades usually 20× or more as long as wide. |
18 Spikelets (3.0-) 3.2-3.8 mm long, fusiform, pointed at summit, attenuate at base, with both glumes attached 0.3-0.5 mm below sterile lemma, the autumnal spikelets 3.5-3.8 mm long; larger vernal blades 3-6 mm wide, the lower and mid- culm blades of similar width; autumnal blades involute |
18 Spikelets 1.8-3.1 mm long, obovate, blunt, and the base not attenuate except in D. arenicoloides with autumnal spikelets 2.3-3.1 mm long; larger vernal blades 2-8 mm wide, the lower usually wider and often shorter than mid- culm blades; autumnal blades involute or flat. |
19 Longest vernal blades to 16 cm, widest vernal blades 4-8 mm, usually longitudinally wrinkled; vernal and autumnal spikelets 2.3-3.1 mm long; autumnal blades flat, the larger to 9 cm × 2-4 mm |
19 Longest vernal blades to 6 ( D. aciculare) or 12 ( D. arenicoloides) cm long, 2-5 mm wide, not noticeably wrinkled; vernal spikelets 1.5-2.8 mm long, autumnal spikelets either 1.5-2.3 ( D. aciculare) or 2.3-3.1 ( D. arenicoloides); autumnal blades involute, the larger to 6 cm × 1.5 mm. |
20 Longest vernal blades to 6 (-8) cm, widest vernal blades 2-5 mm; vernal and autumnal spikelets 1.7-2.3 mm long, blunt, not attenuate, the glumes attached <0.2 mm below sterile lemma; first glumes 0.6-0.9 mm long; larger autumnal blades to 3 cm by 1 mm |
20 Longest vernal blades to 12 cm, widest vernal blades 3-4 (-5) mm; vernal spikelets 2.1-2.8 mm long; autumnal spikelets 2.3-3.1 mm long, pointed, attenuate, the glumes attached 0.3-0.5 mm below sterile lemma; first glumes 0.7-1.5 mm long; larger autumnal blades to 6 cm by 1.5 mm |
17 Lower and often mid- culm nodes bearded with spreading, stiffish, and short-to-long hairs; mid- culm blades usually 15× or less as long as wide. |
21 Blades stiff, often longitudinally ribbed, at least the lower villous or strongly pilose on the abaxial surface, and pilose to hirsute on the adaxial surface, at least proximally. |
22 Spikelets 2.3-3.0 mm long; ligule < 1 mm long; mid- culm blades 4-8 mm wide |
22 Spikelets 1.7-2.0 (-2.3) mm long; ligule 1-2.5 mm long; mid- culm leaves 2-5 mm wide |
21 Blades not noticeably stiff nor longitudinally ribbed, pubescent or strigose underneath, glabrous above or with a few long hairs near the base. |
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23 Spikelet bases not noticeably attenuate, apices rounded to obtuse; first glume < ½ as long as spikelet, attached < 0.3 mm below expansion of second glume and sterile lemma; larger vernal blades 5-12 mm wide. |
24 Culms 50-140 cm long; lowest internodes usually purplish; leaf sheaths often viscid-spotted; leaf blades glabrous abaxially, glabrous and scabrous adaxially; spikelets 1.8-2.2 mm long |
24 Culms 15-60 cm long; lowest internodes usually olive- or bluish-green; leaf sheaths not viscid-spotted; leaf blades appressed- pubescent abaxially, glabrous and smooth to appressed pubescent adaxially; spikelets 2.1-3.1 mm long. |
25 Spikelets 2.1-2.6 mm long; lower culm blades usually sparsely appressed- pubescent on both surfaces, eciliate or ciliate at the base only |
25 Spikelets 2.5-3.1 mm long; lower culm blades usually glabrous adaxially except for long hairs at or near the margin (appearing ciliate), appressed- pubescent abaxially |
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2 Leaf blades, at least the lower, cordate or subcordate at the base, 4-25 mm wide. |
3 Culm blades 4-12 mm wide; spikelets obpyriform when viewed dorsally, strongly plano- convex when viewed laterally, usually markedly reddish-purple basally; fertile lemma papillose |
3 Culm blades 5-25 mm wide; spikelets elliptic to elliptic- obovoid when viewed dorsally or laterally, greenish to faintly purple-tinged basally; fertile lemma not papillose. |
4 Ligule ciliate, 0.2-0.8 mm long; culm blades 5-14 mm wide; spikelets 1.8-2.6 mm long; first glumes 0.5-1 mm long |
4 Ligule an eciliate membrane 0-0.3 mm long; culm blades 5-25 cm wide; spikelets 2.0-3.7 mm long; first glumes 0.5-2.6 mm long. |
5 Internodes crisp- puberulent; larger culm blades 4-8 (-11) cm long, 5-10 (-12) mm wide, broadest near the base; spikelets 2.1-2.7 mm long; first glumes 0.7-0.9 mm long |
5 Internodes glabrous to sparsely pubescent, larger culm blades 5-18 cm long, 5-25 mm wide, broadest near the middle or broadly linear; spikelets 2.0-3.7 mm long; first glumes 0.5-2.6 mm long. |
6 Cauline blades 5-18 cm long, 6-14 mm wide, averaging about 10 × as long as wide, the margins nearly parallel; spikelets 2.9-3.7 mm long; first glumes 11-26 mm long, 2/5 or more as long as the spikelets |
6 Cauline blades 7-12 cm long, (6-) 12-25 mm wide, ovate- lanceolate, averaging about 6 × as long as wide, the margins curved most of their length; spikelets 2.0-3.2 mm long; first glumes 5-10 mm long, about 1/4 as long as spikelets. |
7 Culms erect; blades more nearly symmetrical; spikelets 2.0-3.2 mm long; sterile lemma apex usually blunt to rounded |
7 Culms basally decumbent; blades strongly asymmetrical- falcate; spikelets 3.0-3.2 mm long; sterile lemma apex usually pointed |
2 Leaf blades tapering to the base, 2-12 mm wide. |
8 Ligule a stramineous to light brown membrane, with or without terminal cilia. |
9 Ligule a ciliate membrane; spikelets (2.6) 2.8-3.4 (3.6) mm long; first glume (0.9) 1.1-1.6 mm long |
9 Ligule an eciliate membrane; spikelets 1.6-2.8 (3.0) mm long; first glume 0.3-1.1 mm long. |
10 Panicle rachis smooth, pellucid- punctate; first glume 0.3-0.6 (-0.8 ) mm long, as broad as or broader than long, truncate to obtuse; larger leaves 10-25 cm long, 8-15 mm wide; ligule 0.5-1.3 mm long; lowest elongate culm internode > 2 mm in diameter; lowest nodes usually glabrous or pubescent |
10 Panicle rachis scabrous or smooth, not pellucid- punctate; first glume 0.5-1.1 mm long, longer than wide, rounded to acute; larger leaves 3.5-12 cm long, 3-9 mm wide; ligule 0.1-0.6 mm long; lowest elongate culm internode < 2 mm in diameter; lowest nodes retrorsely bearded or glabrous. |
11 Lowest nodes usually retrorsely bearded; ligules (0.1-) 0.3-0.6 mm long; largest vernal blades 7-12 cm long, (4.5-) 6-9 mm wide; panicle peduncle scabrous; spikelets ovate- lanceolate, acute, 2.0-2.4 mm long; first glume lanceolate, blunt to acute; fertile lemma smooth |
11 Lowest nodes usually glabrous; ligules 0.1-0.2 (-0.3) mm long; largest vernal blades 3.5-7 cm long, 3-6 mm wide; panicle peduncle smooth; spikelets elliptic, blunt to acute, 1.6-2.2 mm long; first glume ovate to rotund, rounded to acute; fertile lemma papillose |
8 Ligule of short white hairs or absent. |
12 Leaves basally disposed, usually matted or cushion-forming, larger than the mid and upper culm leaves; blade margins uniformly papillose- ciliate; culms branching only at the base, 0.5-3.5 dm tall; internodes glabrous or sparsely pubescent |
12 Basal leaves usually rosette-forming, not matted or cushion-forming, usually much smaller than culm leaves; blade margins glabrous, or ciliate only below the middle (or sometimes papillose- ciliate throughout in D. portoricense ssp. patulum, which has densely puberulent internodes); culms branching at the nodes in age, 1.5-7.5 dm tall. |
13 Blades progressively longer upwards on culm, the larger 9-20 cm long and 3-8 mm wide, (15-) 20 × or more as long as wide, firm but not stiff, not longitudinally grooved or wrinkled; blade adaxial surface (weakly-) strongly scabrous; sheaths glabrous; second glume and sterile lemma exceeding fertile lemma |
13 Blades similar or more often decreasing in size upwards on culm, the larger 3-16 cm long and 2-25 mm wide; if 15 × or more as long as wide, then blades stiff and longitudinally grooved or wrinkled (sect. Angustifolia); blade adaxial surface smooth to moderately scabrous; sheaths glabrous or pilose; second glume and sterile lemma shorter than to exceeding fertile lemma. |
14 Blades of mid- culm leaves typically long and stiff, acuminate, linear or narrowly lanceolate, usually > 10× as long as wide, only 2-6 mm wide when < 8 cm long. |
15 Vegetative parts glabrous (spikelets pubescent, lowest internodes and sheaths sometimes sparsely pubescent, blades and sheaths sometimes ciliate); mature panicles less than ¼ as wide as long, the branches erect- ascending, the spikelets often subsecund; autumnal blades 4-10 cm long, involute, < 2 mm wide; spikelets 1.8-2.2 mm long. |
16 Larger vernal blades 5-8 cm long and 3-5 mm wide; vernal panicles usually less than ¼ as wide as long, spikelets often subsecund along the strongly ascending to erect branches; spikelets 1.8-2.2 mm long, second glume and sterile lemma pubescent, summits blunt, about equaling fertile lemma; [of coastal wetlands and Piedmont prairies from NC and AR south to the Caribbean and Central America] |
16 Larger vernal blades 5-9 cm long and 2-3 mm wide; vernal panicles usually ¼ to ½ as wide as long, the branches ascending; spikelets 2.3-3.0 mm long, second glume and sterile lemma sparsely pubescent to glabrous, summits pointed to blunt, exceeding fertile lemma; [of c. and s. FL] |
15 Vegetative parts pubescent, at least in the lower portion of plant; mature panicles usually more than half as wide as long, the branches spreading- ascending, the spikelets not noticeably subsecund; autumnal blades 1-6 cm long, involute and < 2 mm wide in D. aciculare and D. arenicoloides, or to 9 cm long, flat and 2-4 mm wide in D. angustifolium ( autumnal blade dimensions not yet known for D. wilcoxianum); spikelets 1.5-3.2 mm long. |
17 Culms 15-35 cm long; all culm leaf blades long- hirsute on both surfaces, their sheaths densely papillose- hirsute; leaf blades of the primary branches often exceeding the immature vernal panicles |
17 Culms 15-75 cm long; culm leaf blades glabrous to sparsely pubescent, or the lower softly villous abaxially in D. arenicoloides; lower sheaths usually villous, mid- culm and upper sheaths glabrous (though often ciliate basally); leaf blades of primary branches not exceeding immature vernal panicles. |
18 Spikelets (3.0-) 3.2-3.8 mm long, fusiform, pointed at summit, attenuate at base, with both glumes attached 0.3-0.5 mm below sterile lemma, the autumnal spikelets 3.5-3.8 mm long; larger vernal leaf blades 3-6 mm wide, the lower and mid- culm leaf blades of similar width; autumnal leaf blades involute |
18 Spikelets 1.8-3.1 mm long, obovate, blunt, and the base not attenuate (except in D. arenicoloides with autumnal spikelets 2.3-3.1 mm long); larger vernal leaf blades 2-8 mm wide, the lower usually wider and often shorter than mid- culm leaf blades; autumnal leaf blades involute or flat. |
19 Longest vernal blades to 16 cm, widest vernal leaf blades 4-8 mm, usually longitudinally wrinkled; vernal and autumnal spikelets 2.3-3.1 mm long; autumnal leaf blades flat, the larger to 9 cm by 2-4 mm |
19 Longest vernal leaf blades to 6 cm ( D. aciculare ) or 12 cm ( D. arenicoloides) long, 2-5 mm wide, not noticeably wrinkled; vernal spikelets 1.5-2.8 mm long, autumnal spikelets either 1.5-2.3 ( D. aciculare) or 2.3-3.1 ( D. arenicoloides); autumnal leaf blades involute, the larger to 6 cm by 1.5 mm. |
20 Longest vernal leaf blades to 12 cm, widest vernal leaf blades 3-4 (-5) mm; vernal spikelets 2.1-2.8 mm long; autumnal spikelets 2.3-3.1 mm long, pointed, attenuate, the glumes attached 0.3-0.5 mm below sterile lemma; first glumes 0.7-1.5 mm long; larger autumnal leaf blades to 6 cm by 1.5 mm |
 Show caption*© Janet Wright, some rights reserved (CC BY-NC), uploaded by Janet Wright Longest vernal leaf blades to 6 (-8) cm, widest vernal leaf blades 2-5 mm; vernal and autumnal spikelets 1.7-2.3 mm long, blunt, not attenuate, the glumes attached < 0.2 mm below sterile lemma; first glumes 0.6-0.9 mm long; larger autumnal leaf blades to 3 cm by 1 mm |
14 Blades of mid- culm leaves lanceolate, thin or firm but not stiff, usually < 10× as long as wide, usually 7 mm or more wide when as much as 8 cm long. |
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21 Spikelet bases not noticeably attenuate, apices rounded to acute; first glume < ½ as long as spikelet, attached < 0.3 mm below expansion of second glume and sterile lemma. |
22 Spikelets 2.9-3.8 mm long, broadly elliptic, rounded at the summit, with broad and thick nerves |
22 Spikelets 2.1-2.9 mm long, elliptic or obovate, rounded or pointed at the summit, the nerves often raised, but not broad and thick. |
23 Culm internodes and sheaths glabrous, sparsely pilose, or villous. |
24 Culms 50-150 cm long; at least lowest sheaths papillose- pilose. |
25 Lowest internodes usually purple- villous; nodes retrorsely (-spreading) bearded; spikelets 1.8-2.2 mm long, moderately densely pubescent; first glume broadly ovate, subacute, 0.4-0.7 mm long, usually < 1.5 × as long as wide; second glume about as long as sterile and fertile lemmas; fertile lemma 1.7-1.8 mm long |
25 Lowest internodes glabrous or pubescent or spreading villous, usually not purplish; nodes glabrous, sparsely pubescent to sparsely bearded; spikelets 2.2-2.8 (-3.0) mm long, sparsely pubescent; first glume 0.7-1.1 mm long, usually > 1.5 × as long as wide; second glume shorter than sterile and fertile lemmas; fertile lemma 2.1-2.2 mm long |
24 Culms 18-100 cm long; sheaths glabrous or the lowest softly pubescent but not papillose- pilose. |
26 Spikelets strongly plano- convex when viewed laterally, obpyriform when viewed dorsally, (2.1-) 2.2-2.6 mm long; fertile lemma and palea papillose or smooth; first glume usually broadened above base, rounded or broadly tapered distally; glume bases often reddish-purple. |
27 Culm leaves 2-5 mm wide; fertile lemma and palea smooth, shiny |
27 Culm leaves 4-12 mm wide; fertile lemma and palea papillose-roughened |
26 Spikelets biconvex to elliptic when viewed laterally, variously shaped but not obpyriform when viewed dorsally; fertile lemma and palea smooth or reticulate (or papillose in D. lucidum with weak and sprawling culms and spikelets 1.7-2.3 mm long); first glume usually tapered from near base to apex; glume bases various |
23 Culm internodes crisp- puberulent (sparsely so in D. webberianum); sheaths puberulent or glabrous. |
28 Spikelets elliptic, sub- acute to pointed, greenish or faintly purple-tinged basally |
28 Spikelets strongly plano- convex when viewed laterally, obpyriform when viewed dorsally, broadly rounded, usually markedly reddish-purple basally. |
29 Fertile lemma and palea papillose; spikelets 2.2-2.6 mm long; lower culm blades 6-12 mm wide, glabrous |
29 Fertile lemma and palea smooth (minutely reticulate but not papillose); spikelets (1.8) 1.9-2.2 (-2.5) mm long; lower culm blades 2-8 mm wide, glabrous, glabrate, or puberulent (especially abaxially) |
