1 Spikelets 2-flowered, often dorsally compressed, falling entire at maturity (the abscission below the glumes), the upper floret usually bisexual, the lower one male or sterile; [tribe Paniceae]

  2 Lemma margins hyaline, flat; lower glumes various (absent, < ¼ the length, or longer than the upper glume)

  2 Lemma margins not hyaline, frequently involute; lower glumes absent or < ¼ the length of the upper glume.

    3 Spikelets with lower lemmas (and lower glumes, if present) adjacent to the branch axes.

      4 Lower glumes absent

      4 Lower glumes present on at least most spikelets

    3 Spikelets with upper lemmas (and upper glumes, if present) adjacent or appressed to the branch axes.

        5 Both glumes absent from all or most spikelets

        5 Upper or both glumes present on all spikelets.

          6 Lower glumes usually absent; upper lemmas smooth to slightly rugose

          6 Lower glumes present; upper lemmas rugose and verrucose

1 Spikelets 1-, 2-, or many-flowered, usually terete or somewhat laterally compressed, either abscising at maturing above the glumes or if 2-flowered then both florets bisexual, or the upper sterile; [tribes Cynodonteae and Zoysieae]

             7 Spikes normally solitary (rarely 2), divergent at the summit of the culm; second glume with a recurved spine arising from the back; fresh plants aromatic with a citrus odor; [tribe Cynodonteae; subtribe “incertae sedis”]

             7 Spikes normally 2 or more, alternate, digitate, subdigitate, or verticillate along the main inflorescence axis; second glume lacking a recurved spine; fresh plants not aromatic with a citrus odor.

               8 Spikes arranged along the central inflorescence axis alternately, solitary at each node or inflorescences consisting of a solitary spikelike raceme (Zoysia).

                 9 Spikelets with 1 bisexual floret, sometimes also accompanied by modified male, sterile, or rudimentary florets above the fertile floret.

                   10 Spikelets with modified male, sterile, or rudimentary florets above the fertile floret; [plants of uplands]; [tribe Cynodonteae; subtribe Boutelouinae]

                   10 Spikelets lacking any modified florets; [tribe Zoysieae; subtribes Sporobolinae and Zoysiinae]

                     11 Spikelets with 1 fertile floret accompanied by a sterile, reduced floret; inflorescence of 1-many spike-like panicles (the branches appressed to strongly divergent); [plants of wetlands, primarily saline and coastal]; [tribe Zoysieae; subtribe Sporobolinae]

                     11 Spikelets with 1 solitary fertile floret; inflorescence of solitary spike-like racemes; [waifs or uncommon non-native turf grasses of disturbed areas]; [tribe Zoysieae; subtribe Zoysiinae]

                 9 Spikelets with 2 or more bisexual florets (sometimes also with additional reduced florets); [tribe Cynodonteae; subtribe Eleusininae].

                       12 Ligules 4-8 (-15) mm long, acute to attenuate, entire (lacerate only by tearing)

                       12 Ligules 0.3-5.4 mm long, truncate to obtuse, erose or entire.

                          13 Lemmas 5-veined; ligule 0.8-2.2 mm long, apex erose

               8 Spikes arranged along the central inflorescence axis in a digitate, subdigitate, or verticillate manner, all or most nodes with 2 or more spikes; [tribe Cynodonteae].

                            14 Spikelets with 1 fertile floret (there may also be 1 or more sterile florets); [tribe Cynodonteae; subtribe Eleusininae].

                              15 Spikelets lacking sterile florets

                              15 Spikelets with 1 or more sterile florets.

                                16 Lowest lemmas awned (rarely unawned); upper glumes acute to acuminate, mucronate or short-awned

                                16 Lowest lemmas unawned (or with an awn to 1.2 mm long); upper glumes truncate or bilobed, sometimes short-awned from between the lobes

                            14 Spikelets with 2 or more fertile florets.

                                  17 Spikes to 7 cm long, terminating in a point (the spikes acuminate); [tribe Cynodonteae; subtribe “incertae sedis”]

                                  17 Spikes to 22 cm long, terminating in a functional or rudimentary spikelet (the spikes acute to obtuse); [tribe Cynodonteae; subtribe Eleusininae].

                                    18 Lemmas glabrous

                                    18 Lemmas pubescent, at least towards the base.

                                       19 Lemma apices obtuse to truncate or emarginate

                                       19 Lemma apices acute

1 Lemma awn 3-branched (the lateral 2 sometimes very reduced compared to the central); [tribe Aristideae]

1 Lemma awned with a simple awn.

  2 Upper glumes present, 1-veined; lower glumes absent or much shorter than the upper glumes and veinless; [tribe Brachyelytreae]

  2 Both glumes present, 1-many-veined.

    3 Lemma hardened, distinctly different than the glumes in texture when mature; [tribe Stipeae].

      4 Rhizomatous perennials; primary leaves cauline (the basal leaves < 2 cm long or merely represented by sheaths), 8-16 mm wide

      4 Cespitose perennials; primary leaves basally disposed, 0.2-10 mm wide.

        5 Leaves > 4 mm wide.

          6 Florets 2.5-3.5 mm long; awns 3.4 mm long; [exotic, rarely naturalized]

          6 Florets 5-13 mm long; awns either 7-15 or 30-120 mm long; [exotics or natives].

             7 Leaves 2-8 mm wide, not twisted at the base; awns 30-120 mm long

             7 Leaves 4-10 mm wide, the base twisted so that the abaxial surface is uppermost; awns 7-15 mm long

        5 Leaves < 4 mm wide.

               8 Florets 7-25 mm long; awns 30-225 mm long.

                 9 Palea grooved, longer than the lemma; lemma margins involute, fitting into the paleal groove; [native species, collectively widespread in our area]

                 9 Palea flat, shorter than or equal to the lemma; lemma margin convolute or not overlapping; [exotic species, rare in our area]

                   10 Lemma margins not or only slightly overlapping at maturity; awns 60-190 mm long

                   10 Lemma margins strongly overlapping for their entire length at maturity; awns 40-120 mm long

               8 Florets 1.5-4.5 mm long; awns 1-35 mm long

                     11 Leaves 0.2-0.6 mm wide; florets 1.5-2.5 mm long; awns 15-35 mm long

                     11 Leaves 0.5-10 mm wide; florets 2.2-4.5 mm long; awns 1-15 mm long.

                       12 Leaves 0.5-1.8 mm wide; central vein of the lemma not prominent; [native species]

                       12 Leaves 2-10 mm wide; [rare exotic species]

    3 Lemma neither hardened nor distinctly different than the glumes in texture when mature.

                          13 Spikelets 18-32 mm long; [tribe Poeae]

                          13 Spikelets 1.1-8 mm long.

                            14 All spikelets sessile or subsessile and arrayed along inflorescence axes (racemes) divergent from the central axis (but not both overlapping one another and clearly ranked on one side of the axis, so as to be keyed under Key H).

                              15 Inflorescences without disarticulating branches; lower glumes 1.5-3 mm long (Muhlenbergia paniculata) or (2-) 3.5-7 mm long (Gymnopogon); spikelets disarticulating above the glumes (which often remain on the inflorescence); spikelets strongly appressed to the raceme axes; sheaths strongly overlapping or not , if so then at least on the upper culm, therefore hiding the culm; [tribe Cynodonteae; subtribe “incertae sedis”]

                                16 Blades with thick, white margins and well-developed midrib; inflorescence branches strongly divergent; glumes unequal, usually shorter (sometimes only slightly so) than the solitary floret

                                16 Blades lacking both thick, white margins and well-developed midribs; glumes subequal, usually exceeding the 1-2(4) floret(s)

                            14 Spikelets pedicellate and arrayed in a more complex, open (and sometimes loosely contracted) panicle.

                                  17 Lemma surrounded by a tuft of callus hairs; [tribe Poeae]

                                  17 Lemma not surrounded by callus hairs.

                                    18 Spikelets disarticulated below the glumes, the spikelet falling intact, leaving a naked pedicel; [tribe Poeae]

                                       19 Lemma awns (when present) 0.2-1.5 mm long; culms to 200 cm tall; plants cespitose or rhizomatous perennials

                                       19 Lemma awns 5.0-14.5 mm long; culms to 60 cm tall; plants tufted annuals

                                    18 Spikelets disarticulated above the glumes, the floret falling, leaving the glumes attached to the pedicels.

                                         20 Lemmas faintly 5-veined; awn from the back of the lemma; lower glume longer than the lemma; palea much shorter than the lemma (or absent); [tribe Poeae]

                                         20 Lemmas strongly 3-veined; awn from the tip of the lemma; lower glume shorter than (rarely equaling) the lemma; palea about equaling the lemma; [tribe Cynodonteae; subtribe Muhlenbergiinae]