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Key to Poaceae

Poaceae

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1 Plant a woody grass, growing as a shrub or tree (the culms perennial, woody, to 25 m tall), with complex branching systems from the upper nodes; leaves strongly dimorphic, those of the main culm sheathing, those of the branches or culm tips pseudopetiolate
1 Plant an herb (the culms annual, not truly woody, to 5 m tall), lacking complex branching systems from the upper nodes; leaves not dimorphic, none of them pseudopetiolate.
  2 Plant a robust grass, culms usually > 2 m tall and usually > 5 mm in diameter at the base
  2 Plant a small to medium grass, culms < 2 m tall and usually also < 5 mm in diameter at the base.
    3 Spikelets either modified into asexual, purplish bulblets, or partially or wholly concealed either by spines, hooks, and/or involucres, or partially or wholly concealed by being imbedded in a fleshy rachis or cob.
      4 Fertile spikelets either absent (spikelets modified into asexual, purplish bulblets) or variously spiny or bead like
      4 Fertile spikelets embedded in a fleshy rachis (resembling a rattail) or a cob
    3 Spikelets apparent, not covered, concealed, embedded, or modified by spines, hooks, or involucres.
        5 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.
          6 Glumes often as long as or longer than the lemmas and concealing the florets; spikelets usually arranged in obvious pairs or triplets, with 1 spikelet sessile or shortly pedicellate and the other 1 (or 2) spikelets pedicellate (the pedicellate sometimes vestigial or absent)
        5 Spikelets 1-, 2-, or many-flowered, usually terete or somewhat laterally compressed, either abscising at maturity above the glumes or if 2-flowered then both florets bisexual, or the upper sterile.
             7 Inflorescence of one or more spikes, the spikelets sessile (or very short-pedicelled) on the spike axis, 1-more per node, characteristically in 2-more ranks (these either on opposite sides of the axis or crowded on one side), the individual spikelets borne more-or-less touching one another.
               8 Spikelets borne in a single terminal spike or raceme (an extension of the culm), usually 2-ranked on opposite sides of the axis
               8 Spikelets borne on 1-many spikes (the spikes themselves arranged digitately, subdigitately, or racemosely on the culm) in 2 (or more) rows; spikelets often on one side of the spike axis
             7 Inflorescence paniculate, sometimes somewhat to very congested, but then not as above.
                 9 Spikelets with a single bisexual floret, and no staminate, sterile, or reduced florets present (occasional spikelets of Muhlenbergia can have 2-3 florets).
                   10 Glumes present; palea various; [habitats various].
                     11 Inflorescences loose and open, or if relatively dense, then with discernible branches, and thus lobed or asymmetrical.
                 9 Spikelets with 2-many florets, including bisexual, staminate, reduced, or sterile flowers.