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Key to Digitaria
https://fsus.ncbg.unc.edu/main.php?pg=show-key.php&keyid=39760
1 Inflorescence a simple open panicle, with well-developed primary and secondary branches, the entire panicle usually detaching at maturity; spikelets solitary (or in pairs or triplets), on short to long pedicels, the pedicels mostly >2x as long as the spikelets, mostly spreading (sometimes distally appressed on branches); [Leptoloma]. | |
3 Lower lemmas 5-veined; veins equally spaced; spikelets densely pubescent; [e. OK and e. TX westwards]. | |
1 Inflorescences digitate or sub-digitate, or with primary branches alternately arranged along a central axis; with (1) 2-3+ spikelets per node on primary branches, arranged in two rows along one side of the branch (and usually appressed on branches); the entire inflorescence not detaching at maturity. | |
5 Inflorescences of primary branches alternately arranged along a central axis; all the rachilla internodes more or less conspicuously elongated, hence upper florets stipitate; spikelets 3.0-6.6 mm long, the lower lemmas and upper glumes with conspicuously long marginal hairs, these generally spreading and at least ½ as long as the spikelet at maturity); upper lemmas dark brown at maturity; [Trichachne]. | |
6 Lower lemma with 3 nerves on the back, evenly spaced or not. | |
5 Inflorescences digitate, sub-digitate, or with alternately arranged primary branches; the rachilla internodes not conspicuously elongated, thus the upper florets not stipitate; lower lemma and upper glume without conspicuous marginal pubescence (or if with hairs, these not ca. ½ as long as the lower lemma and upper glume); spikelets 1.2-4.1 mm long; upper lemmas variously colored at maturity (including dark brown); [Digitaria]. | |
9 Inflorescence branches (each "finger") not at all winged, the axes usually triquetrous only (with 3 distinct angles); upper glumes 3-veined. | |
13 Spikelets 1.3-1.9 (-2.2) mm long; panicle branches 3-13 cm long; culms 10-80 cm tall | |
13 Spikelets 2.0-2.8 mm long; panicle branches 10-25 cm long; culms 75-100 cm tall (to 150 cm tall in D. villosa). | |
9 Inflorescence branches not merely triquetrous, instead each "finger" at least minimally winged (< ½ as wide as midribs) or widened (> ½ as wide as midribs); upper glumes 3-7 veined. | |
16 Spikelets 1.2-1.7 mm long; lower glumes absent (or reduced to veinless, membranous rim); wings of the rachis at least ½ was wide or wider than the midribs | |
17 Plants conspicuously stoloniferous, the stolons long and branching; leaves few (3-4), clustered at the base of plants, the blades 1.5-4.0 cm long; panicles usually with 2 widely divergent primary spike-like branches (occasionally 3 or 4, these extra "fingers" often reduced in size) | |
17 Plants lacking stolons; leaves few or numerous, the blades (1.5-) 4.0-9.0 cm long, if clustered at the base of plants, usually at least some blades > 4 cm long; panicles with 2-7 primary spike-like branches (often at least 3 per inflorescence). | |
18 Culms decumbent and rooting at the nodes; spikelets lanceolate, 1.5-1.7 mm long; panicles with 2-4 spike-like primary branches, the inflorescence racemose (the "fingers" not in evident verticils); [endemic to dry sandy habitats in Hernando and Marion counties, FL] | |
18 Culms erect, usually not branching from upper nodes; spikelets narrowly elliptic, 1.2-1.7 mm long; panicles with 2-7 spike-like branches, once or twice verticillate; [non-native of disturbed habitats, widespread in our flora area] | |
16 Spikelets 1.7-3.5 mm long; lower glumes present or absent; wings narrow or widened, relative to width of the midrib. | |
19 Spikelets 1.7-2.8 mm long; plants primarily annuals; culms 20-70 cm long, decumbent, rooting and branching at the lower nodes. | |
20 Plants never with axillary panicles concealed in the lower leaf sheaths; panicles bearing spikelets in unequally pedicellate pairs (at least on lower and middle portions of the inflorescence); leaf blades 1.5-2.5 mm wide; sheaths mostly glabrous, sometimes with long scattered hairs basally only if not entirely glabrous; [waif] | |
22 Spikelets variously pubescent, 2.0-3.6 mm long (only obscurely pubescent in D. simpsonii, but spikelets at least 3.0 mm long), the upper glumes ca. as long as the spikelets; ligules not fimbriate; blades pilose or hirsute (sometimes nearly glabrous in D. texana); plants usually decumbent and branching at lower nodes (D. simpsonii and D. texana) OR if the plants tufted and erect, then spikelets 2.4-2.8 mm long (D. subcalva). | |
24 Spikelets 2.4-2.8 mm long; primary inflorescence branches 2-4, the inflorescence lax, diffuse, and gray to purplish-gray; pedicels on upper paired spikelets longer (2.5-3.0 mm); leaf sheaths strongly papillose-hispid; [endemic to wet, fringing calcareous prairies, peninsular FL] | |
24 Spikelets 2.0-3.6 mm long; primary inflorescence branches 5-12, the inflorescence dense and mostly greenish; pedicels on upper paired spikelets shorter (1.0-2.5 mm long); leaf sheaths weakly papillose-hispid; [endemic to coastal prairies of TX, adventive in coastal VA and SC] | |
25 Spikelets 1.5-2.4 mm long; plants annual or nearly so, culms sprawling or mat-forming. | |
26 Spikelets (1.7-) 2.1-3.4 long, variously pubescent; lower portions of the panicles with spikelets in unequally pedicellate pairs; leaf blades pilose or pubescent, the hairs usually < 1.5 mm long | |
27 Spikelets 2.1-2.4; sheaths with scattered papillose-based hairs, ligules erose; the inflorescences with the lower most branches whorled (the upper branches paired or solitary; on depauperate inflorescences merely 2-3 branches opposite or whorled); [primarily c. and s. FL in our area, a waif in MS, AL, and SC] | |
25 Spikelets (2.4-) 2.5-4.1 mm long; plants annual or perennial, culms erect, decumbent, or mat-forming. | |
28 Plants perennial and usually stoloniferous, sometimes also rhizomatous; culms erect or decumbent, not rooting at the lower nodes (except D. milanjiana which does or does not root); [uncommon non-natives]. | |
29 Midveins of the lower lemmas smooth throughout; basal sheaths glabrous or often densely pubescent (the hairs 4-6 mm long); spikelets wooly pubescent, the hairs of variable length (sometimes > 1 mm long); rhizomes sometimes present, if so, these giving the plant bases a knotty appearance; [throughout FL] | |
28 Plants annual or nearly so, lacking stolons and never rhizomatous; culms erect but also often long-decumbent and usually rooting at the lower nodes; [natives and non-natives, collectively widespread]. | |
30 Spikelet pairs dimorphic in their pubescence, the lower lemmas of the upper spikelets (of each spikelet pair) with widely divergent marginal hairs, the lower lemmas of the lower spikelets (of each spikelet pair) glabrous or with appressed hairs; lower lemmas of the sessile spikelet with 5 equidistant veins | |
30 Spikelet pairs homomorphic, the lower lemmas of the upper and lower spikelets not conspicuously differing in their pubescence types; lower lemmas of the sessile spikelet with lateral veins crowded towards the margins (well separated from the midvein). | |
31 Lower glumes 0.2-0.8 mm long; spikelets often purple-tinged; [widespread, weedy]. | |