Grass Family

Anisantha

1 Lemmas 20-36mm ....................................................................................................................................................................... Great Brome
1 Lemmas 9-20mm.
  2 Lemmas 9-13mm; inflorescence compound, the larger branches with 3-8 spikelets (except in weak plants); spikelets with more than 3
   sterile apical florets ............................................................................................................................................................. Drooping Brome
  2 Lemmas 13-20mm; inflorescence simple or the larger branches slightly branched and with up to 3(5) spikelets; spikelets with 1-2 sterile
   apical florets............................................................................................................................................................................. Barren Brome

Bromus

1 Seed thick, with inrolled margins; lemma with margins wrapped around seed when mature, hence lemma margins not overlapping next
  higher lemma, but rhachilla more or less revealed between florets; rhachilla breaking up tardily................................................Rye Brome
1 Seed thin, flat or with weakly inrolled margins; lemma margins not wrapped around seed when mature, overlapping next higher lemma
  and obscuring rhachilla; rhachilla breaking up readily
  2 Anthers 3.5-5mm, at least half as long as lemmas; panicle branches long, forming very open panicle .................................. Field Brome
  2 Anthers 0.2.3mm, less than half as long as lemmas; panicles various, often not very open.
    3 Awns curved or bent outward at maturity, their apices widely diverging ......................................................................Japanese Brome
    3 Awns more or less straight to slightly flexuous or curved at maturity, the apices of those of the more apical lemmas more or less
     parallel or even convergent (if more or less curved outward the culms procumbent to ascending).
      4 Panicle more or less dense, usually with all pedicels shorter than spikelets; lemmas papery, with prominent veins; anthers
       0.5-1.5(2)mm ..........................................................................................................................................................................Soft Brome
      4 Panicle more or less lax with at least some pedicels longer than spikelets; lemmas rather coriaceous, with rather obscure veins;
       anthers 1-3mm.
       5 Lemmas 6.5-8mm; anthers mostly 1.5-3mm; spikelets 10-16mm; lowest rhachilla-segment mostly 0.7-1mm ........Smooth Brome
       5 Lemmas 8-11mm; anthers mostly 1-1.5mm; spikelets 15-28mm; lowest rhachilla-segment mostly 1.3-1.7mm .......Meadow Brome

Agrostis

1 Palea 1/2-3/4 as long as lemma, 0.6-1.2mm long; introduced, usually in disturbed habitats; flowering June-October.
  2 Ligule mostly 0.5-2mm long, truncate; panicle branches naked toward base, diffuse when in fruit, spikelets well-separated ..................
   ................................................................................................................................................................................................. Common Bent
  2 Ligule mostly 2.5-6mm long, acute, rounded, or truncate; panicle branches (some of them) with spikelets to near base, spikelets usually
   clustered.
   3 Leaves 3-8mm wide; inflorescence triangular-ovoid, branches widely spreading at maturity, usually reddish; plant with rhizomes,
     without stolons ...................................................................................................................................................................... Redtop Bent
   3 Leaves mostly 1-3mm wide; inflorescence narrowly ovoid, the branches ascending at maturity, usually tan; plant without rhizomes,
     with or without stolons ...................................................................................................................................................... Creeping Bent
1 Palea < 2/5 as long as lemma, 0-0.5mm long; plants native, typically in more or less natural habitats; flowering March-November.
  4 Lemma with a (2-)3-5mm long, geniculate awn .......................................................................................................................Brown Bent
  4 Lemma awnless or with a 0-3mm long awn, this often straight.
   5 Spikelets 1.2-2mm long; anthers 0.3-0.6mm long; lemma never awned; plants flowering Mar-Jul ...................................Winter Bent
   5 Spikelets 1.8-3.5(-3.7)mm long; anthers 0.3-1.5mm long; lemma awnless or awned; plants flowering Jun-Nov.
     6 Lemma 1.8-3mm long, minutely but copiously scabrous (at 20× or more); anthers 0.7-1.2mm long; spikelets (2.3-)2.7-3.5(-3.7)mm
       long, usually clustered near tips of branchlets; panicle branches scabrous; culms to 150cm tall; [wet habitats] ...Coastal Bog Bent
     6 Lemma 1.4-2mm long, glabrous; anthers 0.3-0.6mm long; spikelets (1.8-)2.2-2.7(-3.2)mm long, usually not clustered near tips of
       branchlets; panicle branches glabrous to scabrous; culms to 1m tall; [various habitats] ............................................... Upland Bent

Calamagrostis

1 Awns attached on upper 2/5 of lemmas, 0.5-2mm long, straight ................................................................................ Nuttall's Reed-grass
1 Awns attached on lower ½ of lemmas, 0.9-6mm long, straight or bent ................................................................... Blue-joint Reed-grass

Elymus

Identification notes: Measurements of the spike include the awns, but measurements of spikelets and its components do not. Rachis internodes should be measured near the middle of the spike. Glume widths are measured at the widest point, or if the widest point is not apparent, at about 5 mm above the glume base.

1 Spikelets solitary at each node (occasionally paired at lowest nodes); glumes and lemmas awned or unawned; plants cespitose to strongly
  rhizomatous .......................................................................................................................................................................... Common Couch
1 Spikelets 2-3(-5) at each node; glumes and lemmas usually awned; plants usually cespitose, occasionally short-rhizomatous.
  2 Glume bases flat, thin, and evidently veined, or indurate for < 1mm, bodies not exceeding adjacent (usually 8-15mm long) lemmas;
   lemma awns usually curving outward; spikes usually nodding to pendent; internodes (2-)4-12mm long ..................Nodding Wild-rye
  2 Glume bases terete, indurate, and lacking evident veins for 0.5-4mm, bodies (unless indistinct from awns) exceeding adjacent
   (usually 6-12mm long) lemmas; lemma awns straight; spikes erect or nodding; internodes 2-5mm long.
   3 Glumes persistent, 0.2-1mm wide, with 2-4 veins, the basal 0.5-2mm essentially straight; lemmas rarely glabrous; spikelets with
     1-3(-4) florets; spikes nodding, exserted ......................................................................................................................... Hairy Wild-rye
   3 Glumes disarticulating with lowest floret, 0.7-2.3mm wide, with (2-)3-5(-8) veins, basal 1-4mm clearly bowed-out; lemmas often
     glabrous; spikelets with (2-)3-5(-6) florets.
     4 Spikes 2.5-6cm wide, exserted; lemma awns 15-40mm long; blades glabrous or villous.............................. Southeastern Wild-rye
     4 Spikes 0.7-2cm wide (including awns), exserted or sheathed; lemma awns 1-15(20)mm long; spikelets appressed to slightly
       spreading; blades usually glabrous to scabridulous ............................................................................................... Virginia Wild-rye

Dichanthelium and Panicum

1 Annual.
  2 Spikelets tuberculate .....................................................................................................................................................Warty Panic-grass
  2 Spikelets not tuberculate.
   3 First glume not more than one-quarter the length of the spikelet .....................................................................Spreading Panic-grass
   3 First glume one-half the length of the spikelet.
    4 Panicle more than half the total height of the plant .............................................................................................................Witch-grass
    4 Panicle not more than half the height of the plant ....................................................................................................Wood Panic-grass
1 Perennial.
  5 Spikelets short pedicelled along one side of the rachis, forming spikelike racemes ........................................ Maidencane Panic-grass
  5 Spikelets in open, rarely contracted panicles.
   6 Basal leaves different from culm leaves, usually forming winter rosettes.
    7 Spikelets glabrous.
     8 Spikelets 3mm or more long, strongly nerved.
      9 Spikelets pointed, blades elongated ...................................................................................................................Starved Panic-grass
      9 Spikelets blunt, blades not elongated, 3.2-3.3mm long sheaths of some of them hispid ....................................................................
       ...................................................................................................................................Few-flowered Panic-grass var. scribnerianum
     8 Spikelets less than 3mm long.
      10 Second glume and sterile lemma exceeding the fruit and pointed beyond it, spikelets 2.2-2.9mm long.
       11 Spikelets elliptic, fruit 2mm long ....................................................................................................................Scabrid Panic-grass
       11 Spikelets ovate, broadest below the middle, 2mm or less.
        12 Sheaths (at least the secondary) hispid ........................................................................................................Scabrid Panic-grass
        12 Sheaths glabrous ........................................................................................................................................... Cryptic Panic-grass
      10 Second glume and sterile lemma, not pointed beyond the fruit.
       13 Ligule 2-3mm long ............................................................................................................................................Eaton's Panic-grass
       13 Ligule obsolete.
        14 Nodes bearded ....................................................................................................................................Round-fruited Panic-grass
        14 Nodes not bearded.
         15 Spikelets 1.2-1.4mm, blades not over. 30mm long, 1.5-3mm wide ...............................................................Carpet Panic-grass
         15 Spikelets 1.5mm or more.
          16 Spikelets 1.5-1.6mm blades 50-80mm long, 4-7mm wide ..............................................................................Blue Panic-grass
          16 Spikelets 2mm long or more.
           17 Culms soon prostrate, vine-like, branches divaricate .....................................................................................Bog Panic-grass
           17 Culms not vine-like, branches not divaricate.
            18 Nodes glabrous ; autumnal form upright ............................................................................................... Forked Panic-grass
            18 Nodes, at least lowest, usually bearded, autumnal form, top-heavy and reclining ....Forked Panic-grass var. barbulatum
    7 Spikelets pubescent.
    19 Spikelets 3mm or more long.
     20 Blades elongated leaves 2-5mm wide ..................................................................................................................Starved Panic-grass
     20 Blades not elongated.
      21 Nodes bearded, leaves 15-30mm wide .................................................................................................................Bosc's Panic-grass
      21 Nodes not bearded.
       22 Sheaths glabrous ............................................................................................................................................Variable Panic-grass
       22 Sheaths pubescent.
        23 Pubescence appressed, spikelets 3.5-4 ..............................................................................................Few-flowered Panic-grass
        23 Pubescence spreading.
         24 Blades 20mm wide ..............................................................................................................................Deer-tongue Panic-grass
         24 Blades 6-12mm wide .......................................................................................Few-flowered Panic-grass var. scribnerianum
    19 Spikelets less than 3mm long.
     25 Blades elongated .........................................................................................................................................Slim-leaved Panic-grass
     25 Blades not elongated.
      26 Spikelets attenuated at the base.
       27 Autumnal blades flat, blades 80-120 X 4-8mm ................................................................................Narrow-leaved Panic-grass
       27 Autumnal blades involute, blades 40-60 X 2-5mm ...........................................................................Needle-leaved Panic-grass
      26 Spikelets not attenuated at base.
       28 Ligule manifest 1-5mm long.
        29 Sheaths glabrous.
         30 Panicle narrow ¼ to 1/3 as wide as long ....................................................................................................Eaton's Panic-grass
         30 Panicle open nearly as wide as long ..............................................................................Tapered Panic-grass var. lindheimeri
        29 Sheaths pubescent.
         31 Ligule 1-1.5mm long, culms and sheaths appressed pubescent.
          32 Spikelets 1.8-1.9mm long, plant bluish green ....................................................................................... American Panic-grass
          32 Spikelets 1.5mm long, nearly glabrous, plant olivaceous .................................................American Panic-grass var. oricola
         31 Ligule 2-5mm long.
          33 Spikelets 1-1.3mm long, culm and sheath soft appressed pubescent.
           34 Spikelets 1. 2-1.3mm long ......................................................................................................................Tapered Panic-grass
           34 Spikelets not over 1mm long .................................................................................................................Wright's Panic-grass
          33 Spikelets more than 1.5mm long.
           35 Spikelets not over 2mm long.
            36 Plant grayish, velvety pubescent ..........................................................................................................Tapered Panic-grass
            36 Plant pubescent, but not velvety.
             37 Upper surface of blade glabrous ...........................................................................Tapered Panic-grass var. fasciculatum
             37 Upper surface of blade pubescent.
              38 Spikelets 1.3-1.5mm long, blade long, pilose above .........................................................................Matting Panic-grass
              38 Spikelets 1.6-2mm long, blade appressed, pubescent above ...........................................................Tapered Panic-grass
           35 Spikelets 2.2 mm. or more.
            39 Pubescence on culm horizontal, spreading ...........................................................................................Woolly Panic-grass
            39 Pubescence on culms appressed ............................................................................Oval-leaved Panic-grass var. addisoni
       28 Ligule obsolete or less than 1mm long.
        40 Nodes bearded.
         41 Spikelets 1.5-1.6mm long ................................................................................................................Round-fruited Panic-grass
         41 Spikelets 2.2mm or more ................................................................................................Mattamuskeet Panic-grass var. clutei
        40 Nodes not bearded ...........................................................................................................................Mattamuskeet Panic-grass
         42 Plants densely gray velvety throughout, a viscid ring below the nodes ......................................................Velvety Panic-grass
         42 Plants not gray velvety.
          43 Some sheaths pilose or hispid.
           44 Pubescence papillose hispid.
            45 Spikelets 2.3-2.6mm, pointed ...............................................................................................................Scabrid Panic-grass
            45 Spikelets obovate, obtuse, 3mm long ...........................................................................................Deer-tongue Panic-grass
           44 Pubescence ascending pilose.
            46 Spikelets 2-2.5mm long.
             47 Spikelets 2.4mm long ...................................................................................................................Oval-leaved Panic-grass
             47 Spikelets 2-2.1mm long ................................................................................................................Oval-leaved Panic-grass
            46 Spikelets not over 1.3-1.4mm long, nearly globular .........................................................................American Panic-grass
          43 Sheaths glabrous or pubescent only.
           48 Spikelets globular, 1.8mm long, blades cordate, ciliate at the base.
            49 Panicle as broad as long ............................................................................................................Round-fruited Panic-grass
            49 Panicle narrow, more than 2/3 as broad as long ........................................................................Small-fruited Panic-grass
           48 Spikelets not globular.
            50 Culms prostrate and vinelike, branches divaricate, spikelets not over 2.1mm long ....................................Bog Panic-grass
            50 Not vine-like nor divaricate.
             51 Spikelets 2.5-3mm long.
              52 Blades rarely more than 10mm broad, culms crisp puberulent .......................................................Variable Panic-grass
              52 Blades usually 1.5mm or more in width, culms glabrous .................................................................Variable Panic-grass
             51 Spikelets under 2.5mm long.
              53 Spikelets not over 2.3 mm. long ..........................................................................................................Forked Panic-grass
              53 Spikelets not over 1.7mm. long.
               54 Culms conspicuously puberulent, spikelets turgid .....................................................................American Panic-grass
               54 Culms glabrous ..................................................................................................................................Carpet Panic-grass
   6 Basal leaves not different from those of the culm.
    55 With creeping scaly root stocks, spikelets long pedicelled, not secund, in open or contracted panicle.
     56 Panicle diffuse.
      57 Panicle open, spikelets 3.5-5mm long, beaked ..............................................................................................................Switch-grass
      57 Panicle more or less contracted, 3.2mm long, not beaked ...................................................................... Switch-grass var. cubense
     56 Panicle contracted, seashore species ......................................................................................................................Bitter Panic-grass
    55 Not forming a creeping scaly rootstock.
     58 Rootstocks present, culms but little compressed, spikelets set obliquely on their appressed pedicels ............Beaked Panic-grass
     58 Root stocks none, culm strongly compressed, spikelets not obliquely arranged.
      59 Ligules ciliate, basal leaves half the length of the culm, panicle longer than the upper leaves ......................Red-top Panic-grass
      59 Ligules not ciliate, basal leaves in short tufts, upper leaves about equaling the panicle ....................................Dense Panic-grass

Setaria

1 Bristles 4-12 below each spikelet.
  2 Annual, with fibrous roots ......................................................................................................................................... Yellow Bristle-grass
  2 Perennial, noticeably rhizomatous ...................................................................................................................... Perennial Bristle-grass
1 Bristles 1-3 (rarely 6) below each spikelet.
  3 Bristles retrorsely scabrous ......................................................................................................................................... Rough Bristle-grass
  3 Bristles antrorsely scabrous.
   4 Upper lemmas smooth and shiny (occasionally with obscure rugosity).
    5 Culms to 1m tall; spikelets ca. 3mm long; [alien, of ruderal sites] ....................................................................... Foxtail Bristle-grass
    5 Culms to 6m tall; spikelets ca. 2mm long; [native, of marshes] .............................................................................. Giant Bristle-grass
   4 Upper lemmas distinctly transversely rugose, dull.
    6 Leaves softly pilose on upper surface; panicles arching and drooping from base; spikelets 2.5-3.0mm long ..Nodding Bristle-grass
    6 Leaves scabrous on the upper surface; panicles nodding only at the tip; spikelets 1.8-2.2mm long .....................Green Bristle-grass

Digitaria

1 Inflorescence an open panicle; spikelets long-pedicellate, borne singly at ends of long panicle branches ................ Diffuse Crab-grass
1 Inflorescence of 2-several spike-like racemes borne digitately or in close proximity near summit of culm; spikelets sessile or
  shortpedicellate, borne more-or-less closely spaced along racemes.
  2 Rachis of each raceme narrow, trigonous, only slightly (if at all) winged ................................................................ Slender Crab-grass
  2 Rachis of each raceme broad (0.5-1 mm wide), winged, the wings as wide as or wider than the rachis proper.
   3 Lower sheaths glabrous; second glume 0.75-1× as long as the first glume (which may be fertile) lemma dark ....Smooth Crab-grass
   3 Lower sheaths pilose; second glume 0.3-0.6× as long (to 0.8× as long in Fringed Crab-grass) as first glume; fertile lemma
     white, tan, or grayish-brown at maturity.
     4 Spikelets (1.7-) 2.5-3.4mm long, averaging 3.0mm long or shorter; leaf blades pilose over upper surface ...........Hairy Crab-grass
     4 Spikelets 2.6-4.1mm long, averaging 3.1mm long or longer; leaf blades glabrous except for a few hairs on upper surface at base
       .............................................................................................................................................................................. Fringed Crab-grass