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Key to Digitaria

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1 Inflorescences an open panicle (as long as wide); spikelets solitary (or paired or in 3’s) on long or short pedicels; pedicels mostly > 2× as long as the spikelets, mostly spreading (sometimes distally appressed on branches); the entire panicle usually detaching at maturity
1 Inflorescences of digitate or sub-digitate primary branches, or primary branches alternately arranged along a central axis; with (1) 2-3 (or more) spikelets per node on primary branches, arranged in two rows along one side of the branch; spikelets appressed on branches; the entire inflorescence not detaching at maturity.
..2 Inflorescences of primary branches alternately arranged along a central axis; all the rachilla internodes more or less conspicuously elongated, hence upper florets stipitate; upper lemmas dark brown at maturity; spikelets 3.0-6.6 mm long, densely short to long pubescent, hairs generally exceeding the length of the spikelet and hairs spreading at maturity; hairs smooth-walled, with acute apices
..2 Inflorescences of digitate or sub-digitate primary branches, or primary branches alternately arranged along a central axis; no conspicuous elongated rachilla internodes, upper floret not stipitate; upper lemmas pale yellow, tan, gray, purple-tinged, purple, brown or dark brown; spikelets 1.3-4.1 mm long, glabrous to variously pubescent; hairs various, smooth or verrucose walled, with acute or dilated apices.
....3 Rachis of each raceme narrow, trigonous, only slightly (if at all) winged.
......4 Spikelets in 2s on the middle portions of the primary branches, the pedicels not adnate; upper lemmas gray, yellow, and/or purple-tinged when immature, purple at maturity
......4 Spikelets in groups of 2-5 on the middle portions of the primary branches, the longer pedicels often adnate to the primary branch for a portion of their lengths; upper lemmas brown when immature, dark brown at maturity.
........5 Spikelets 1.7-2.2 mm long; plants 3-10 dm tall; racemes to 10 cm long; upper sheaths glabrous, lower sheaths glabrous to sparsely pilose
........5 Spikelets 2.0-2.8 mm long; plants 8-15 dm tall; racemes to 25 cm long; upper sheaths glabrous or pilose, lower sheaths densely pilose
....3 Rachis of each raceme broad (0.5-1 mm wide), winged, the wings as wide as or wider than the rachis proper.
..........6 Lower sheaths glabrous; second glume 0.75-1× as long as the first glume (which may be absent or a veinless, membranous rim); fertile lemma dark brown or black at maturity (or pale brown or gray in D. longiflora).
............ 7 Hairs of the spikelet minutely capitate; second glume ca. 1× as long as the first glume; spikelets 1.7-2.3 mm long
............ 7 Hairs of the spikelet not minutely capitate; second glume ca. 0.75× as long as the first glume; spikelets 1.2-1.7 mm long
..........6 Lower sheaths pilose; second glume 0.3-0.6× as long (to 0.8× as long in D. ciliaris) as the first glume; fertile lemma white, tan, or grayish-brown at maturity.
............ ..8 Spikelets 1.5-1.8 mm long, villous with crinkled hairs; pedicels glabrous, terete in cross-section
............ ..8 Spikelets (1.7-) 2.4-4.1 mm long, glabrous, scabrous, or pubescent with straight hairs; pedicels scabrous, 3-angled in cross-section; [section Digitaria].
............ ....9 Spikelets (1.7-) 2.5-3.4 mm long, averaging 3.0 mm long or shorter; leaf blades pilose over the upper surface
............ ....9 Spikelets 2.6-4.1 mm long, averaging 3.1 mm long or longer; leaf blades glabrous except for a few hairs on the upper surface at the base.
............ ......10 Lower lemma of the sessile spikelet with 5 equidistant nerves; lowermost inflorescence node glabrous or pubescent with hairs < 0.4 mm long; apex of the first glume rounded to truncate
............ ......10 Lower lemma of sessile spikelet with the lateral nerves crowded to the margins; lowermost inflorescence node pubescent with hairs > 0.4 mm long; apex of the first glume acute
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