Flora of the Southeastern United States

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].

  2 Spikelets 3.5-4.6 mm long; upper glumes 5-7 veined; anthers > 1 mm long; [TX coastal dunes]

  2 Spikelets 2.2-3.3 mm long; upper glumes 3 (-5)-veined; anthers < 1 mm long; [collectively widespread, of various habitats].

    3 Lower lemmas 7-veined; outer veins not equally spaced; spikelets glabrous to short pubescent; [widespread]

    3 Lower lemmas 5-veined; veins equally spaced; spikelets densely pubescent; [e. OK and e. TX westwards].

      4 Plants without rhizomes, densely cespitose

      4 Plants with long rhizomes, loosely cespitose or loosely tufted

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 5 equally spaced nerves on the back

          6 Lower lemma with 3 nerves on the back, evenly spaced or not.

             7 Spikelets (3.7-) 4-6.6 mm long, with ochraceous indumentum, narrowly ellipsoid, apex acuminate; lower lemma glabrous on both sides of midnerve and either pilose or alternately pilose and glabrous in the remaining zones

             7 Spikelets 3-4.5 mm long, with hairs whitish-silvery or whitish with purplish tints, narrowly ovate or ovate, apex acuminate or abruptly acuminate; lower lemma glabrous on both sides of the midnerve and pilose in the remaining zones.

               8 Spikelets 3-4.5 mm long, ovate, apex abruptly acuminate; panicle 5-19 cm long, with 4-10 appressed racemes, densely spiculate, on an axis 5-7 cm long

               8 Spikelets 3-3.2 mm long, ellipsoid or linear-lanceolate, apex acuminate; panicle 10-18 cm long, with 6-9 patent racemes, loosely spiculate, on an axis 7-10 cm long

        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.

                   10 Spikelets glabrous or nearly so (sometimes the upper glume apices sparsely pubescent); [FL only in our area].

                     11 Spikelets 2.3-2.4 mm long; leaf blades 2.0-4.5 mm wide; sheaths and leaf blades densely hairy with papillose-based hairs (but not densely gray-villous); plants erect, unbranched, and not rooting at lower nodes

                     11 Spikelets 2.7-3.2 mm long; leaf blades 2.0-2.2 mm wide; sheaths and leaf blades densely gray-villous on both surfaces; plants erect to somewhat decumbent, not rooting at lower nodes but often branching at aerial nodes

                   10 Spikelets pubescent (at least the lower lemmas), often with gland-tipped hairs; the upper glumes [collectively widespread, including FL].

                       12 Basal leaf sheaths glabrous; cauline leaf blades ca. 1 mm wide; spikelets 1.5-1.6 mm long; [s. FL]

                       12 Basal leaf sheaths variously pubescent; cauline leaf blades 1-6 mm wide; spikelets 1.3-1.9 (-2.2) mm long (D. filiformis) or 2.0-2.8 mm long.

                          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).

                            14 Basal and lower leaf sheaths appressed pubescent, but the hairs not papillose-based; plants cespitose perennials; spikelets 2.2-2.5 mm long; ligules 2.0-3.0 mm long; culms to 100 cm tall; [endemic to Lake County, FL]

                            14 Basal and lower leaf sheaths with spreading, papillose-based hairs; spikelets 2.0-2.8 mm long; panicle branches 10-25 cm long; ligules 0.3-1.5 mm long; culms 75-150 cm tall; [widespread]

                 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.

                              15 Basal and lower sheaths glabrous or nearly so (D. nuda sheaths mostly glabrous, sometimes with long hairs basally, but the leaf blades also primarily glabrous).

                                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 2.5-3.5 mm long; plants perennial; culms 50-250 cm long, erect or decumbent, rooting or not at the lower nodes; [waif]

                                       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 always with axillary panicles in the lower leaf sheaths (these sometimes concealed by the sheaths); panicles bearing spikelets in groups of 3; lower portions of the pedicels adnate to the axes; leaf blades 3.0-5.0 mm wide; sheaths sometimes sparsely pubescent; [widespread non-native]

                                         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]

                              15 Basal and lower sheaths variously pubescent.

                                           21 Inflorescence rachises narrowly winged (no more than ½ the width of the midrib).

                                             22 Spikelets glabrous, 1.7-2.3 mm long, the upper glumes < ½ as long as the spikelets; ligules fimbriate; blades scabrous adaxially and sometimes with sparse hairs basally, but otherwise mostly glabrous (abaxially); plants densely tufted perennials

                                             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).

                                               23 Spikelets 3.0-3.3 mm long, the upper glumes 7-9 veined; plants annual or weakly perennial

                                               23 Spikelets 2.0-2.8 (-3.6) mm long, the upper glumes 3-5 veined (D. texana) or 5-7 veined (D. subcalva); plants perennial.

                                                 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]

                                           21 Inflorescence rachis with broadened wings (> ½ the width of the midrib or ca. as wide).

                                                    25 Spikelets 1.5-2.4 mm long; plants annual or nearly so, culms sprawling or mat-forming.

                                                      26 Spikelets 1.5-1.8 mm long, villous with crinkled hairs; lower portions of the panicles with spikelets in triplets; leaf blades conspicuously pubescent on both surfaces, the longer hairs 1.5-2.5 mm long and papillose-based

                                                      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]

                                                        27 Spikelets (1.7-) 2.5-3.4 mm long, averaging 3.0 mm; sheaths keeled, ligules not erose; plants annual, decumbent and rooting at the nodes; leaf blades pilose on the upper surface; the inflorescence subdigitate, lacking whorled branches below; [widespread in the US]

                                                    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]

                                                            29 Midveins of the lower lemmas scabrous (at least distally); basal sheaths glabrous, sometimes pubescent (if so, the hairs shorter); spikelets often at least somewhat pubescent, but the hairs never conspicuously long (< 1 mm long); [c. 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 absent or no longer than 0.1 mm; spikelets usually green; [waif]

                                                                 31 Lower glumes 0.2-0.8 mm long; spikelets often purple-tinged; [widespread, weedy].

                                                                   32 Spikelets 2.7-4.1 mm long, the lower glumes 0.2-0.8 mm long; lateral veins of the lower lemmas usually glabrous; leaf blades usually with a few scattered papillose-based hairs at the base of the upper surfaces (occasionally throughout the upper surface); [weedy native]

                                                                   32 Spikelets 1.7-3.4 mm long; the lower glumes 0.2-0.4 mm long; lateral veins of the lower lemmas scabrous for the distal 2/3 of their length; leaf blades usually with papillose-based hairs on both surfaces (sometimes glabrous); [weedy non-native]