2024 Edition • Donate • Get the App • Cite this Page
X

Colors

Data mode

Account

Login
Sign up

Support FSUS...

We've finished our 2024 fundraiser. Many thanks to those who have given! It's not too late to support us (click here)...

X
Keyed in multiple places:

Click the number at the start of a key lead to highlight both that lead and its corresponding lead. Click again to show only the two highlighted leads. Click a third time to return to the full key with the selected leads still highlighted.

Key to Poaceae, Key B: robust herbaceous grasses

Copy permalink to share | Check for keys that lead to this key

1 Inflorescence an array of spikes, the spikelets closely imbricate in 2 rows along the rachis of the spikes, the spikes alternate along the primary inflorescence axis; [tribe Zoysieae; subtribe Sporobolinae]
1 Inflorescence otherwise, either the spikelets embedded or in grooves in an thickened rachis, or the inflorescence a slender or broad panicle.
  2 Spikelets embedded in the thickened rachis (the inflorescence thus like an ear of corn), or fitting into grooves in the thickened rachis (the inflorescence thus cylindrical and resembling a rat's tail). Spikelets unisexual, with male and female spikelets in separate inflorescences or in different parts of the same inflorescence; [tribe Andropogoneae].
    3 Racemes of mixed sex (female below, male above)
    3 Racemes of single sex
 Zea
  2 Spikelets not embedded or fitting into grooves in the rachis, the inflorescence a slender or broad panicle (the spikelets visibly separate and often pedicelled).
      4 Spikelets with a single floret, this unisexual (either pistillate or staminate); plants with aerenchymatous culms, [plants of seasonally or tidally flooded wetlands]; [tribe Oryzeae].
        5 Pistillate spikelets on the upper branches of the panicle, staminate spikelets on the lower branches; lemmas and paleas clasping along their margins; plants annual
        5 Pistillate and staminate spikelets intermingled on the same branches of the inflorescence; lemma margins free; plants perennial
      4 Spikelets with 2 or more florets, at least some of these bisexual; plants without aerenchymatous culms, [plants of uplands or temporarily to seasonally flooded wetlands].
          6 Spikelets with 2-8 florets, these bisexual.
             7 Leaves primarily basal, plants densely cespitose.
               8 Panicles plumose; [tribe Danthonieae]
             7 Leaves cauline; plants short-rhizomatous (somewhat clumped) to long-rhizomatous; [tribe Arundineae].
                 9 Lemmas pilose; rachilla glabrous; plants short-rhizomatous (somewhat clumped); culms to 10 m tall; [plants of uplands or saturated or temporarily flooded wetlands]
                 9 Lemmas glabrous; rachilla sericeous; plants long rhizomatous; culms to 4 m tall; [plants of uplands or saturated, tidally flooded, or seasonally flooded wetlands]
          6 Spikelets almost always with 2 florets, the lower florets sterile or staminate (sometimes reduced to lemmas or completely absent).
image of plant
Show caption*© Nate Hartley, some rights reserved (CC BY-NC), uploaded by Nate Hartley
                   10 Spikelets falling separately, not attached to rachis segments, stalks, or bristles; spikelets <2× as long as wide; [tribe Paniceae].
                     11 Spikelets (at least the terminal) subtended by 1-many stiff, terete bristles
                     11 Spikelets not subtended by stiff bristles.
image of plant
Show caption*© Keith Bradley
                       12 Fertile lemma rugose with cross-venation
                       12 Fertile lemma smooth or hairy, not rugose
image of plant
Show caption*© Scott Ward
                   10 Spikelets falling with attached rachis segments, stalks, or bristles; spikelets >3× as long as wide; [tribe Andropogoneae].
                          13 Pedicelled spikelet differing from the sessile in shape and sex (sometimes represented only by a pedicel).
                            14 Inflorescence of 2-13 digitate (whorled) racemes borne at the summit of a peduncle, the peduncle subtended by a raceme sheath
                            14 Inflorescence a panicle, the branches not subtended by sheaths.
                              15 Pedicelled spikelet represented by pedicel only; apex of sheath bearing 2 auricles 1-10 mm long; [native]
                              15 Pedicelled spikelet present, staminate; apex of sheath truncate; [exotic]
                          13 Pedicelled spikelet similar to the sessile spikelet, both fertile.
                                16 Spikelets falling separately from the persistent rachis
                                16 Spikelets falling in pairs together with sections of the disarticulating rachis
                                  17 Spikelets awned with awns 10-26 mm long; anthers 2; [native, collectively common and widespread]
                                  17 Spikelets unawned or with awns to 5.2 mm long; anthers 3; [exotic, rarely encountered]
                                    18 Spikelets unawned
                                    18 Spikelets with awns 4-5.2 mm long

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

Copy permalink to share | Check for keys that lead to this key

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 Lemmas 1-3-nerved, the nerves strong and obvious; spikelets 1-27 mm long.
    3 Lemma nerves hairy; lemmas slightly to strongly 2-lobed, the midnerve shortly excurrent between the 2 lobes; [tribe Cynodonteae; subtribe Tridentinae].
      4 Palea glabrous or with hairs < 0.5 mm long; plants perennial; inflorescences exserted, conspicuous
      4 Palea long-ciliate on the upper half, the hairs 0.5-2 mm long; plants annual; inflorescences often largely hidden in the upper sheath
    3 Lemma nerves glabrous; lemmas not at all lobed.
        5 Mature spikelets stiff; grains protruding, with a bottle-neck-like beak; [tribe Diarrheneae]
        5 Mature spikelets not stiff; grains neither protruding, nor shaped with a bottleneck-like beak.
          6 Inflorescence branches usually strongly ascendant (sometimes weakly spreading); culms often disarticulating at the first node; [tribe Arundineae]
          6 Inflorescence branches ascending, widely divergent, or nodding; culms not disarticulating at the first node; [collectively widespread, dry to wet sites]
             7 Florets 3-34 per spikelet; lemmas unawned; [tribe Eragrostideae; subtribe Eragrostidinae]
             7 Florets 2-3 per spikelet; lemmas awned or unawned; [tribe Poeae]
  2 Lemmas 5-many-nerved, the nerves often obscure; spikelets 2-70 mm long.
               8 Sheaths united for at least ½ their length.
                 9 Spikelets in dense one-sided clusters on a few stiff branches; spikelets strongly flattened; [tribe Poeae]
                 9 Spikelets in open or somewhat congested panicles, not as above; spikelets slightly to not at all flattened.
                   10 Lemmas 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 Lemmas unawned.
                       12 Lower glumes 1-veined; [plants of wetlands]
                       12 Lower glumes 3-7-veined; [plants of mesic to dry habitats]
               8 Sheaths completely free or united at most up to ½ their length.
                          13 Basal 1-8 florets of the spikelet sterile.
                            14 Ligule membranous (the membrane apex ciliate); lower 1-4 florets sterile; disarticulation above the glumes and between the florets; [of various, usually moist, habitats, collectively widespread]; [tribe Centotheceae]
                            14 Ligule of hairs; lower 2-8 florets sterile; disarticulation below the glumes (the spikelet falling whole); [of coastal dunes, from se. VA southward and westward]; [tribe Eragrostideae; subtribe Uniolinae]
                          13 Lowermost florets of the spikelet fertile; [tribe Poeae].
                              15 Lemmas about as broad as long, spreading at a ca. 90° angle to the rachilla
                              15 Lemmas longer than broad, ascending at an acute angle to the rachilla.
                                16 Lemmas rounded at the apex, not awned.
                                  17 Inflorescence pedicels 0.5-3 mm thick; panicle branches stiff; lemmas coriaceous at maturity
                                  17 Inflorescence pedicels to 0.5 mm thick (if to 0.8 mm as in Sclerochloa dura then culms usually prostrate and leaves also exceeding inflorescence length); panicle branches flexible; lemmas hardened or membranous but not coriaceous at maturity.
                                    18 Inflorescences usually exceeded by the leaves (or sometimes similar in length); culms usually prostrate or procumbent (occasionally ascending); plants often compact and low-growing; mature lemmas hardened
                                    18 Inflorescences exceeding the leaves; culms usually erect; plants compact or not; mature lemmas membranous
                                       19 Lemmas obscurely (3-) 5 (-7) nerved; spikelets 2.5-13 mm long; [habitats usually saline or alkaline]
                                       19 Lemmas prominently 5-9-nerved; spikelets 3.6-6.5 mm long; [habitats non-saline]
                                16 Lemmas acute at the apex, or awned.
                                         20 Callus of the lemmas hairy
 Poa
                                         20 Callus of the lemma glabrous.
                                           21 Lemmas awned.
                                             22 Plant annual; stamen 1
                                             22 Plant perennial; stamens 3.
                                               23 Leaf blades often involute, 0.2-3 mm wide, not auriculate at the base
                                               23 Leaf blades flat, 3-12 mm wide, auriculate at the base
                                           21 Lemmas 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 blades often involute, 0.2-3 mm wide, or flat and 3-12 mm wide, not auriculate at the base
                                                    25 Leaf blades flat, 3-12 mm wide, auriculate at the base