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Key to Poaceae, Key N: grasses with 2+ florets, these readily visible by extending past the glumes

Poaceae

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1 Plants dioecious; plants strongly rhizomatous-clonal; [plants of saline situations, coastal or more rarely inland]; [tribe Cynodonteae; subtribe Monanthochloinae]
1 Plants bisexual; plants cespitose or weakly short- rhizomatous; [plants of various habitats, including saline].
  2 Lemma 1-3-nerved, the nerve strong and obvious; spikelet 1-27 mm long.
    3 Lemma nerve hairy; lemma slightly to strongly 2-lobed, the midnerve shortly excurrent between the 2 lobe; [tribe Cynodonteae; subtribe Tridentinae].
      4 Palea glabrous or with hair < 0.5 mm long; plants perennial; inflorescence exserted, conspicuous
      4 Palea long-ciliate on the upper half, the hair 0.5-2 mm long; plants annual; inflorescence often largely hidden in the upper sheath
    3 Lemma nerve glabrous; lemma not at all lobed.
        5 Mature spikelet stiff; grain protruding, with a bottle-neck-like beak; [tribe Diarrheneae]
        5 Mature spikelet not stiff; grain neither protruding, nor shaped with a bottleneck-like beak.
          6 Inflorescence branches usually strongly ascendant (sometimes weakly spreading); culm often disarticulating at the first node; [tribe Arundineae]
          6 Inflorescence branches ascending, widely divergent, or nodding; culm not disarticulating at the first node; [collectively widespread, dry to wet sites]
             7 Floret 3-34 per spikelet; lemma unawned; [tribe Eragrostideae; subtribe Eragrostidinae]
             7 Floret 2-3 per spikelet; lemma awned or unawned; [tribe Poeae]
  2 Lemma 5-many-nerved, the nerve often obscure; spikelet 2-70 mm long.
               8 Sheath united for at least ½ their length.
                 9 Spikelet in dense one-sided clusters on a few stiff branches; spikelet strongly flattened; [tribe Poeae]
                 9 Spikelet in open or somewhat congested panicle, not as above; spikelet slightly to not at all flattened.
                   10 Lemma awned.
                     11 Callus of the lemma glabrous; [collectively widespread]; [tribe Bromeae]
                     11 Callus of the lemma pubescent; [of VA, WV, KY, and northward]; [tribe Meliceae]
                   10 Lemma unawned.
                       12 Lower glume 1-veined; [plants of wetlands]
                       12 Lower glume 3-7-veined; [plants of mesic to dry habitats]
               8 Sheath completely free or united at most up to ½ their length.
                          13 Basal 1-8 floret of the spikelet sterile.
                            14 Ligule membranous (the membrane apex ciliate); lower 1-4 floret sterile; disarticulation above the glume and between the floret; [of various, usually moist, habitats, collectively widespread]; [tribe Centotheceae]
                            14 Ligule of hair; lower 2-8 floret sterile; disarticulation below the glume (the spikelet falling whole); [of coastal dune, from se. VA southward and westward]; [tribe Eragrostideae; subtribe Uniolinae]
                          13 Lowermost floret of the spikelet fertile; [tribe Poeae].
                              15 Lemma about as broad as long, spreading at a ca. 90° angle to the rachilla
                              15 Lemma longer than broad, ascending at an acute angle to the rachilla.
                                16 Lemma rounded at the apex, not awned.
                                  17 Inflorescence pedicel 0.5-3 mm thick; panicle branches stiff; lemma coriaceous at maturity
                                  17 Inflorescence pedicel to 0.5 mm thick (if to 0.8 mm as in Sclerochloa dura then culm usually prostrate and leaves also exceeding inflorescence length); panicle branches flexible; lemma hardened or membranous but not coriaceous at maturity.
                                    18 Inflorescence usually exceeded by the leaves (or sometimes similar in length); culm usually prostrate or procumbent (occasionally ascending); plants often compact and low-growing; mature lemma hardened
                                    18 Inflorescence exceeding the leaves; culm usually erect; plants compact or not; mature lemma membranous
                                       19 Lemma obscurely (3-) 5 (-7) nerved; spikelet 2.5-13 mm long; [habitats usually saline or alkaline]
                                       19 Lemma prominently 5-9-nerved; spikelet 3.6-6.5 mm long; [habitats non-saline]
                                16 Lemma acute at the apex, or awned.
                                         20 Callus of the lemma hairy
 Poa
                                         20 Callus of the lemma glabrous.
                                           21 Lemma awned.
                                             22 Plant annual; stamen 1
                                             22 Plant perennial; stamen 3.
                                               23 Leaf blade often involute, 0.2-3 mm wide, not auriculate at the base
                                               23 Leaf blade flat, 3-12 mm wide, auriculate at the base
                                           21 Lemma unawned.
                                                 24 Leaf tips blunt, cupped like the prow of a row-boat
 Poa
                                                 24 Leaf tips acuminate, planar or keeled (but not as above).
                                                    25 Leaf blade often involute, 0.2-3 mm wide, or flat and 3-12 mm wide, not auriculate at the base
                                                    25 Leaf blade flat, 3-12 mm wide, auriculate at the base