1 Spikelet 18-32 mm long; [tribe Poeae]

1 Spikelet 0.7-10.8 mm long.

  2 Spikelet clearly orbiculate, the glume keeled

  2 Spikelet variously shaped, sometimes rounded but not clearly orbiculate, the glume keeled or not.

    3 Floret rigid, shining; glume and lemma rounded in ×-section, not keeled; spikelet 2.5-5 mm long; [tribe Poeae]

    3 Floret soft, papery; glume and lemma keeled in ×-section; spikelet 0.7-10.8 mm long.

      4 Floret with a conspicuous tuft of hair on the callus; [tribe Zoysieae; subtribe Sporobolinae]

      4 Floret not conspicuously hairy on the callus.

        5 Lemma 1-veined; ligule of hair; grain becoming mucilaginous when wet; [tribe Zoysieae; subtribe Sporobolinae]

        5 Lemma 1-5-veined; ligule a membrane (the summit sometimes ciliolate); grain not becoming mucilaginous when wet.

          6 Lemma strongly 3-veined; lower glume shorter than (rarely equaling) the lemma; palea about equaling the lemma; [tribe Cynodonteae; subtribe Muhlenbergiinae]

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

  2 Both glume present, 1-many-veined.

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

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

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

        5 Leaves > 4 mm wide.

          6 Floret 2.5-3.5 mm long; awn 3.4 mm long; [exotic, rarely naturalized]

          6 Floret 5-13 mm long; awn either 7-15 or 30-120 mm long; [exotic or natives].

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

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

        5 Leaves < 4 mm wide.

               8 Floret 7-25 mm long; awn 30-225 mm long.

                 9 Palea grooved, longer than the lemma; lemma margin 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 margin not or only slightly overlapping at maturity; awn 60-190 mm long

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

               8 Floret 1.5-4.5 mm long; awn 1-35 mm long

                     11 Leaves 0.2-0.6 mm wide; floret 1.5-2.5 mm long; awn 15-35 mm long

                     11 Leaves 0.5-10 mm wide; floret 2.2-4.5 mm long; awn 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 glume in texture when mature.

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

                          13 Spikelet 1.1-8 mm long.

                            14 All spikelet sessile or subsessile and arrayed along inflorescence axes (raceme) 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 Inflorescence with disarticulating branches; Lower glume 0.9-4 mm long; spikelet disarticulating below the glume, the spikelet falling as a whole; spikelet appressed to divergent from the raceme axes; sheath not strongly overlapping; [tribe Cynodonteae; subtribe Eleusininae]

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

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

                                16 Blade lacking both thick, white margin and well-developed midrib; glume subequal, usually exceeding the 1-2(4) floret(s)

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

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

                                  17 Lemma not surrounded by callus hair.

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

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

                                       19 Lemma awn 5.0-14.5 mm long; culm to 60 cm tall; plants tufted annuals

                                    18 Spikelet disarticulated above the glume, the floret falling, leaving the glume attached to the pedicel.

                                         20 Lemma 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]