Poaceae

Intermountain Flora, v. 6, p. 175

• 1. Spikelets dorsally compressed; perfect floret 1, terminal in the spikelet. Group 1

Spikelets dorsally compressed in Digitaria adscendens

• 1' Spikelets usually laterally compressed, sometimes terete; perfect florets 1 to many, the reduced florets, when present, above the perfect ones.

Spikelets laterally compressed

• 2. Glumes lacking; spikelets very flat, 1-flowered; palea subequal to the lemma and 3-nerved; along water banks in 6-12 inches water; Weber, Davis, Utah counties. Leersia oryzoides

Leersia oryzoides	Leersia oryzoides	Leersia oryzoides

• 2' Glumes present (only 1 in Lolium); spikelets various; palea, if present, 2-nerved.

Lolium spikelet

• 3. Spikelets usually with 2 staminate or rudimentary florets below the terminal fertile floret
• 4. Lower florets staminate; spikelets brown and shiny. Anthoxanthum hirtum = Hierochloe hirta

Anthoxanthum hirtum	Anthoxanthum hirtum	Anthoxanthum hirtum

• 4' Lower florets empty and much reduced; spikelets green or yellowish. Phalaris

Phalaris arundinacea	Phalaris arundinacea	Phalaris arundinacea	Phalaris canariensis

• 3' Spikelets without reduced floret below the perfect floret (except Blepharidachne, which has a rudimentary floret above the perfect one as well)
• 5. Spikelets sessile or subsessile (when more than one at a node some of the group usually pedicelled); inflorescence a single spike, or 2 or more digitately or racemosely arranged spicate branches (in Beckmannia sometimes arranged in panicles). Group 2

Spikelets sessile

• 5' Spikelets pedicellate; inflorescence an open or contracted, sometimes spike-like panicle, rarely a raceme.

Spikelets pedicellate

• 6. Spikelets 2- to many-flowered.
• 7. Glumes shorter than the first floret; lemmas awnless or awned from the tip or from a bifid apex, the awn rarely slightly dorsal. Group 3
• 7' Glumes, at least the second glume as long or longer than the lowest floret; lemmas with dorsal awns or awnless (awned from a bifid apex in Schismus and Koeleria). Group 4

Helictotrichon sempervirens

• 6' Spikelets 1-flowered, rarely with a reduced lemma on the extended rachilla of Calamagrostis. Group 5

• 1. Glumes membranous; sterile lemma resembling the second glume and appearing like a third glume; fertile lemma and palea indurate or at least firmer than the glumes (Tribe 6. Panicea).
• 2. Spikelets subtended by bristles or enclosed in a prickly bur.
• 3. Spikelets subtended by 1 to many bristles, the spikelets decidious and the bristles persistent. Setaria
• 3.1. Second glume as long or nearly as long as the spikelet; spikelet 2-2.7 mm long, each subtended by 1-3-(4) bristles; sheath margins ciliate towards the summit.
• 3.2. Bristles antrorsely scabrous, (4)-5.5-11 mm long; panicle branches not verticillate. Setaria viridis

Setaria viridis	Setaria viridis

• 3.2' Bristles retrorsely scabrous, 2-4.5=(6) mm long; panicle branches verticillate. Setaria verticillata

Setaria verticillata	Setaria verticillata

• 3.1' Second glume 1/2 the length of the spikelet; spikelet 2.8-3.4 mm long, each subtended by 5-12 bristles; sheath margins glabrous. Cenchrus americanus = Setaria glauca

Setaria glauca	Setaria glauca

• 3' Spikelets enclosed in a prickly bur (involucre), the burs dropping intact from the rachis at maturity. Cenchrus longispinus

Cenchrus longispinus	Cenchrus longispinus	Cenchrus longispinus	Cenchrus longispinus

• 2' Spikelets not subtended by bristles or enclosed in a prickly bur.
• 4. Glumes and sterile lemma awnless.
• 5. Spikelets in 1-sided spikes or racemes.
• 6. First glume much reduced to absent, the second glume from 1/3 to as long as the spikelet.

Glumes in Digitaria adscendens

• 7. Plants annual; lemma of the fertile floret firm but not hard, the margines hyaline; racemes more or less digitate. Digitaria
• 7.1. Second glume equaling the length of the spikelet; spikelets 1.8-2.3 mm long; sheaths glabrous, the upper margins sometimes ciliate. Digitaria ischaemum

Digitaria ischaemum	Digitaria ischaemum	Digitaria ischaemum

• 7.1' Second glume 1/3 to 4/5 the length of the spikelet; spikelets 2.5-3.6 mm long; sheaths papillose-pilose.
• 7.2. Blades glabrous or only sparsely papillose-pilose on the upper surface near the throat; lateral nerves of the sterile lemma smooth; second glume 1/2 to 4/5 the length of the spikelet, (1)-1.5-2.5 mm long. Digitaria adscendens

Digitaria adscendens	Digitaria adscendens	Digitaria adscendens

• 7.2' Blades papillose-pilose, the upper surface often densely so; lateral nerves of the sterile lemma often minutely scaberulous; second glume 1/3 to 3/5 the length of the spikelet, 0.8-1.8 mm long. Digitaria sanguinalis

Digitaria sanguinalis	Digitaria sanguinalis	Digitaria sanguinalis

• 7' Plants perennial; lemma of the fertile floret relatively thick and rigid; racemes single or paired, not digitate. Paspalum distichum

Paspalum distichum	Paspalum distichum	Paspalum distichum	Paspalum distichum

• 6' Glumes subequal and as long as the spikelet. Panicum obtusum

Panicum obtusum	Panicum obtusum

• 5' Spikelets in open or compact panicles.
• 8. Second glume and sterile lemma glabrous, or sometimes scaberulous only on the nerves toward the apex; basal leaves similar to the culm leaves, not forming a winter rosette; spikelets all fertile. Panicum

Panicum capillare	Panicum virgatum

• 8' Second glume and sterile lemma short pilose all over (sometimes glabrous in D. oligosanthes); basal leaves distinctly different from the culm leaves, forming a winter rosette; plants passing from one growth phase to another, the so-called vernal phase characterized by simple stems and terminal panicles becoming transformed to the autumnal phase with branched culms and auxillliary, often cleistogamous panicles. Dichanthelium
• 8'1. Spikelets 1.5-2 mm long, the second glume and sterile lemma 1.2-1.8 mm long; ligula hairs 1.5-5 mm long. Dichanthelium acuminatum var. acuminatum = Dichanthelium lanuginosum

Dichanthelium acuminatum	Dichanthelium acuminatum	Dichanthelium acuminatum

• 8'1' Spikelets 2.9-3.5 mm long, the second glume and sterile lemma 2.4-3 mm long; ligula hairs 0.5-1.4 mm long. Dichanthelium oligosanthes

Dichanthelium oligosanthes

• 4' Glumes and sterile lemma usually awned; spikelets in irregular clusters along one side of the panicle branches, the spikelets stiffly hispid. Echinochloa crus-galli

Echinochloa crus-galli	Echinochloa crus-galli	Echinochloa crus-galli

• 1' Glumes indurate, except in Imperata and Zea; sterile lemma, fertile lemma, and palea hyalline or membranous, the 2 lemmas usually alike in texture (Tribe 7. Andropogoneae).
• 9. Plants monoecious; staminate and pistillate spikelets in separate inflorescences; cultivated corn. Zea mays
• 9' Plants not monoecious; spikelets in pairs, one sessile, perfect, the other pedicellate, usually staminate or neuter, the pedicellate one sometimes obsolite, rarely both spikelets pedicellate.
• 10. Spikelets all alike and fertile.
• 11. Pedicelled spikelets present, similar to the sessile spikelets; panicle silky-pubescent with hairs 8-11 mm long; Kane, San Juan counties. Imperata brevifolia

Imperata brevifolia	Imperata brevifolia	Imperata brevifolia

• 11' Pedicelled spikelets completely absent, represented only by a pedicel; panicle branchlets and pedicels yellowish-villous with hairs 0.5-1.2 mm long; Washington, Kane, San Juan, Grand counties. Sorghastrum nutans

Sorghastrum nutans	Sorghastrum nutans	Sorghastrum nutans

• 10' Spikelets not all alike, the pedicelled ones staminate or sterile.
• 12. Inflorescence an open or contracted panicle with spikelets alternately arranged in 1- to few-jointed rachises. Sorghum
• 12.1. Rhizomatous perennials; leaf blades 4-15-(25) mm broad; sessile spikelet enclosing the mature caryopsis; terminal segment of the awn 4-7 mm long. Sorghum halepense

Sorghum halepense	Sorghum halepense

• 12.1' Robust annuals; leaf blades (12)-20-52 mm broad; sessile spikelet usually spread apart by the caryopsis at maturity; terminal segment of the awn 2-4 mm long. Sorghum bicolor

Sorghum bicolor	Sorghum bicolor

• 12' Inflorescence of 1 to several racemes, the racemes of several joints (internodes).
• 13. Racemes solitary on each peduncle, digitate; rachis joints oblique and hollow at the summit. Schizachyrium scoparium

Schizachyrium scoparium	Schizachyrium scoparium

• 13' Racemes 2 to several on each peduncle.
• 14. Racemes 2-6 on each peduncle, digitate; rachis joints slender, sometimes with a shallow groove on 1 side. Andropogon
• 14.1. Hairs of the rachis joints and pedicels yellowish, (3)-4-5 mm long; awns mostly less than 5 mm long, sometimes absent; plant strongly rhizomatous. Andropogon gerardii ssp. hallii = Andropogon hallii
• 14.1' Hairs of the rachis joints and pedicels whitish or grayish, 1-3-(3.5) mm long; awns (8)-12-20 mm long; plants tufted, sometimes with short rhizomes. Andropogon gerardii ssp. gerardii = Andropogon gerardii
• Not in the key: Andropogon glomeratus var. pumilus

Andropogon gerardii	Andropogon glomeratus

• 14' Racemes numerous, clustered in a leafless panicle, usually on a relatively long axis; pedicels and rachis joints flat, each with a central, translucent groove. Bothriochloa
• 14'1. Pedicellate spikelets about as long as the sessile spikelets; inflorescence reddish to purplish. Bothriochloa ischaemum var. songarica
• 14'1' Sessile spikelet shorter and narrower than stalked spikelet; inflorescence tan to silvery.
• 14'2. Sessile spikelet 2.5-4.5 mm long; lemma awn 8-18 mm long. Bothriochloa laguroides ssp. torreyana
• 14'2' Sessile spikelet 4.5-8.5 mm long; lemma awn 15-30 mm long.
• 14'3. Main axis of the panicle less than 5 cm long, nearly always shorter than the branches; branches 2-9 per panicle, 4-7 cm long; upper culm nodes with hairs mostly 3-7 mm long. Bothriochloa springfeldii
• 14'3' Main axis of the panicle often more than 5 cm long, mostly equal to or longer than the branches; branches often more than 9 per panicle, 2-9 cm long; upper culm nodes with hairs mostly 1-2-(3) mm long. Bothriochloa barbinodis

• 1. Spikelets or spikelet clusters alternate on opposite sides of the continuous or discontinuous rachis; spike terminal, solitary; leaves often auriculate.
• 2. First glume lacking, except in the terminal spikelet; spikelets placed edgewise to the rachis. Lolium

Lolium perenne

• 2' First glume present, sometimes much reduced; spikelets placed flatwise to the rachis, except in Hilaria

Flatwise attachment in Agropyron elongatum

• 3. Plants annual; introduced weeds and cultivated plants.
• 4. Spikelets cylindric, fitting into concavities of the rachis. Aegilops cylindrica

Aegilops cylindrica

• 4' Spikelets laterally compressed, the rachis not concave above each joint.
• 5. Spikelets 2 or more at each node of the rachis.
• 6. Spikelets 2 per node; rachis not disarticulating; glumes connate at the base. Taeniatherum caput-medusae

Taeniatherum caput-medusae	Taeniatherum caput-medusae

• 6' Spikelets 3 per node; rachis disarticulating (except in Hordeum vulgare); glumes not connate at the base. Hordeum
• 5' Spikelets solitary at each node of the rachis.
• 7. Spikes small, 0.8-2 cm long; glumes with rather thickened, indurate margins, somewhat connate at the base. Eremopyrum triticeum

Eremopyrum triticeum	Eremopyrum triticeum	Eremopyrum triticeum

• 7' Spikes larger, 3-17 cm long; glumes with scarious margins, not at all connate at the base.
• 8. Glumes ovate, 3- or more-nerved; spikelets (2-) 3- to 5-flowered. Triticum aestivum

Triticum aestivum	Triticum aestivum

• 8' Glumes subulate, 1- (3)-nerved; spikelets 2-flowered. Secale cereale

Secale cereale	Secale cereale

• 3' Plants perennial; mostly native species.
• 9. Rachis continuous, disarticulating occurring above the glumes (below the glumes in Hilaria belangeri).
• 10. Spikelets in groups of 3, the spikelet clusters falling entire from a zig-zag rachis; central spikelet fertile, 1-flowered, the 2 lateral spikelets staminate, mostly 2-flowered; glumes broad, obtuse to truncate, irregularly lacerate or awned. Hilaria
• 10.1. Culms and often the leaves lanate pubescent, (3.5)-5-8.5-(10) dm tall; Washington, San Juan counties. Hilaria rigida = Pleuraphis rigida

Hilaria rigida	Hilaria rigida	Hilaria rigida

• 10.1' Culms and leaves glabrous to hirsutulous, 1.5-4-(6.5) dm tall; most counties, except Wasatch Range. Hilaria jamesii = Pleuraphis jamesii

Hilaria jamesii	Hilaria jamesii	Hilaria jamesii

• 10' Spikelets 1 to several at a node, the rachis not zig-zag; spikelets all similar, usually 2- to many-flowered; glumes entire, usually acute or acuminate.
• 11. Glumes subulate to narrowly lanceolate; lemmas usually arranged 90 deg from normal position due to twisting of the rachilla, thus the florets not strictly in 2 ranks; spikelets 1 or usually 2 or more at each node of the rachis. Elymus
• 11' Glumes narrowly lanceolate to broader; lemmas arranged in normal position above the glumes so the florets are in 2 ranks; spikelets mostly solitary at each node of the rachis or rarely 2 in robust plants. Agropyron

Agropyron repens	Agropyron repens	Agropyron repens

• 9' Rachis disarticulating at maturity.
• 12. Spikelets more than 1 at each node of the rachis.
• 13. Spikelets mostly 3 to a node, 1-flowered, the lateral pair of spikelets usually pedicellate and reduced, the central one sessile and fertile (all 3 sessile and usually fertile in the annual H. vulgare). Hordeum
• 13' Spikelets mostly 2 to a node, if 1 or 3 (rare) not as above, usually alike, (1)-2-6-flowered.
• 14. Glumes 3-7 mm long; awn of the lemma 0.5-3 mm long. Psathyrostachys juncea = Elymus junceus

Psathyrostachys juncea	Psathyrostachys juncea	Psathyrostachys juncea

• 14' Glumes 12-85 mm long; awn of the lemma 5-120 mm long.
• 15. Spikes 8-10 mm broad; body of the lemma 8-10 mm long.
• 16. Plants 1-4.5-(6.5) dm tall; glumes subulate, 25-85 mm long. Sitanion
• 16' Plants (5)-6-10 dm tall, those less than 6 dm tall either with glumes linear-lanceolate and 2- to 4-nerved or the glumes less than 24 mm long; sterile hybrids. Elysitanion
• 15' Spikes about 5 mm broad; body of the lemma 6-8 mm long; sterile hybrids. Agrohordeum
• 12' Spikelets solitary at each node of the rachis.
• 17. Culms erect; sterile hybrids of low to midmontane elevations. Agrositanion
• 17' Culms prostrate-spreading, or at least decumbent at the base; fertile subalpine or alpine species. Elymus scribneri = Agropyron scribneri

Elymus scribneri	Elymus scribneri

• 1' Spikelets in 2 rows, along 2 sides of a 3-angles, continuous rachis, forming 1-sided spikes or racemes, these spicate branches usually 2 to several (1 in Sclerochloa), digitately, racemosely or paniculately arranged on a central axis; leaves non-auriculate.
• 18. Spikelets with 3-12 perfect florets ( (1)-2- to 3-flowered in Leptochloa filiformis).
• 19. Spikes solitary, terminal. Sclerochloa dura

Sclerochloa dura

• 19' Spikes 2 to several, digitate to racemosely arranged on a central axis.
• 20. Spikes 2-4, digitate, sometimes with 1 or 2 spikes racemosely arranged below. Eleusine indica

Eleusine indica	Eleusine indica

• 20' Spikes numerous, racemosely arranged on an elongated axis. Leptochloa

Leptochloa fusca	Leptochloa panicea

• 18' Spikelets with only 1 perfect floret, often with additional imperfect florets, these often only rudimentary.
• 21. Spikelets with 1 or more modified florets above the perfect one.
• 22. Spikes digitate or nearly so. Chloris

Chloris virgata	Chloris virgata	Chloris virgata

Chloris verticillata	Chloris verticillata	Chloris verticillata

• 22' Spikes racemose along a main axis, or reduced to 1. Bouteloua
• 22'1. Spikes 1-50 per culm, falling entire at maturity, each spike bearing only 1-8-(10) spikelets (subgenus Bouteloua).
• 22'2. Spikes bearing 1-(2) spikelets; lemma 6-7.5 mm long; Texas; Utah single observation is likely misidentified. Bouteloua uniflora

Bouteloua uniflora

• 22'2' Spikes bearing (2)-3-10 spikelets; lemma 3.8-6 mm long.
• 22'2'1. First (proximal) spikelet on each branch with 1 floret, the remaining spikelets with 2 florets; plants annual; panicles with 1-15 branches, mostly ascending to spreading; Garfield, Washington, Kane counties. Bouteloua aristidoides

Bouteloua aristidoides	Bouteloua aristidoides

• 22'2'1' Spikelets all alike or with 2 or more florets; plant perennial; panicles with 9-80 branches, spreading to pendulous; Garfield, Washington, Kane counties. Bouteloua curtipendula

Bouteloua curtipendula

• 22'1' Spikes no more than 8 per culm, the florets falling from the persistent glumes, each spike bearing (8)-10-80 spikelets (subgenus Chondrosum).
• 22'3. Plants perennial.
• 22'4. Culms internodes white-lanate to arachnoid pubescent. Bouteloua eriopoda

Bouteloua eriopoda	Bouteloua eriopoda	Bouteloua eriopoda

• 22'4' Culms glabrous to scaberulous, not lanate or arachnoid pubescent.
• 22'5. Spikes 3 to 7, rarely only 2 per culm; second glume 2-3-(4) mm long, awnless. Bouteloua trifida

Bouteloua trifida	Bouteloua trifida	Bouteloua trifida

• 22'5' Spikes normally 2, rarely 1, 3 or 4 per culm; second glume (3.5)-4-6-(6.5) mm long, an awn tip up to 1.2 mm long; upper glumes of at least some spikelets with papillose-based hairs.
• 22'6. Rachis terminating in a spikelet that is sometimes sterile; callus of the sterile lemma densely bearded. Bouteloua gracilis

Bouteloua gracilis	Bouteloua gracilis

• 22'6' Rachis extending beyond the terminal spikelet as a needle; callus of the sterile lemma naked. Bouteloua hirsuta ssp. hirsuta

Bouteloua hirsuta	Bouteloua hirsuta

• 22'3' Plants annual.
• 22'7. Spikes 3 to 6 per culm; second glume 1.5-2.5 mm long. Bouteloua barbata

Bouteloua barbata	Bouteloua barbata

• 22'7' Spikes solitary; second glume 4-5.5 mm long. Bouteloua simplex

Bouteloua simplex	Bouteloua simplex

• 22'1" Stoloniferous; upper leaves exceeding the inflorescences; Daggett county. Bouteloua dactyloides

Bouteloua dactyloides	Bouteloua dactyloides

• 21' Spikelets without additional modified florets, the rachilla sometimes prolonged.
• 23. Spikelets disarticulating above the glumes.
• 24. Spikes racemose along a wiry axis; lemma 3-4.7 mm long; rachilla not prolonged. Schedonnardus paniculatus

Schedonnardus paniculatus

• 24' Spikes digitate; lemma 1.8-2.5 mm long; rachilla prolonged behind the palea. Cynodon dactylon

Cynodon dactylon

• 23' Spikelets disarticulating below the glumes and falling entire.
• 25. Spikes (2)-4-15 cm long; glumes narrow-lanceolate to subulate, 3.5-20 mm long; lemma 6.2-9.5 mm long. Spartina
• 25.1. Second glume 10-20 mm long, including the awn, greatly exceeding the lemma; spikes (4)-5-15 cm long; plants robust, (7)-10-30 dm tall; blades mostly more than 5 mm broad. Spartina pectinata

Spartina pectinata	Spartina pectinata

• 25.1' Second glume 7-8.5-(10) mm long, awnless or merely mucronate and only barely exceeding the lemma; spikes 2-4.5-(7) cm long; plants 3-7.5=(10) dm tall; blades rarely more than 5 mm broad. Spartina gracilis

Spartina gracilis	Spartina gracilis

• 25' Spikes less than 1.8 cm long; glumes broad, rounded-triangular, 2-3 mm long; lemma 1.8-3.5 mm long. Beckmannia syzigachne

Beckmannia syzigachne	Beckmannia syzigachne	Beckmannia syzigachne

Group 3

• 1. Plants dioecious (staminate and pistilate flowers on different plants) or monoecious; lemmas glabrous to scabrous, not villous.
• 2. Plants densely tufted, erect from short rhizomes; lemmas scabrous; dry mountain slopes. Leucopoa kingii

Leucopoa kingii male plant	Leucopoa kingii female plant	Leucopoa kingii male (left) and female (right) spikelets	Leucopoa kingii

• 2' Plants not densely tufted, spreading by long, creeping rhizomes; lemmas glabrous; saline or alcaline places. Distichlis spicata

Distichlis spicata female plant	Distichlis spicata male plant

• 1' Plants not dioecious, except in some species of Poa with villous lemmas.
• 3. Plants 2-3 m tall, stout reeds with large plume-like panicles; rachilla with long, spreading hairs. Phragmites australis
• 3.1. Plants are less than 7 ft, make dense stands; the first glume is less than 4 mm, the second glume is less than 6 mm; the middle and upper stem internodes dull, ridged, and tan-colored during the growing season; ligules 0.4–0.9 mm long; leaves green bluish; leaf sheathes are tight, not deciduos in age. Phragmites australis var. australis
• 3.1' Plant are taller, up to 15+ ft, do not make dense stands; the first glume is longer than 4 mm, the second glume is longer than 6 mm; the middle to upper stem internodes are are smooth, shiny and red-brown to dark red-brown during the growing season; ligules 1.0–1.7 mm long; leaves gree yellowish; leaf sheathes are loose, deciduos in age. Phragmites australis ssp. americanus

Phragmites australis

• 3' Plants not reed-like, rarely up to 2 m tall; rachilla without long, spreading hairs.
• 4. Lemmas mostly 5- or more-nerved; if 3-nerved, the nerves usually obscure.
• 5. Callus of the florets bearded.
• 6. Lemmas awnless, entire. Poa
• 6' Lemmas awned from a bifid apex, the awn 8-15 mm long; Daggett, Duchesne, Uintah, Garfield counties. Schizachne purpurascens

Schizachne purpurascens	Schizachne purpurascens

• 5' Callus of the florets not bearded.
• 7. Lemmas keeled on the back.
• 8. Spikelets strongly compressed, crowded in dense, 1-sided panicles. Dactylis glomerata

Dactylis glomerata

• 8' Spikelets not strongly compressed (except some Bromus), not crouded in dense 1-sided panicles.
• 9. Spikelets large, mostly more than 15 mm long; lemmas awned, often from a minutely bifid apex, or nearly awnless. Bromus
• 9' Spikelets small, mostly less than 10 mm long.
• 10. Lemmas with an awn 2.5-3 mm long; C Utah. Festuca dasyclada
• 10' Lemmas awnless. Poa
• 7' Lemmas rounded on the back.
• 11. Glumes papery; spikelet disarticulating above or below the glumes; terminal floret similar to the fertile florets, or often reduced to an obovoid, blunt rudiment. Melica

Melica stricta

• 11' Glumes not papery; spikelet disarticulating above the glumes; reduced florets not unlike the others.
• 12. Nerves of the lemma parallel, not converging at the summit, or but only slightly so.
• 13. Sheaths of the leaves usually open; nerves of the lemma (3) 5 (7), mostly obscure; often of saline or alcaline soils. Puccinellia

Puccinellia nuttalliana	Puccinellia nuttalliana

• 13' Sheaths of the leaves usually closed; nerves of the lemma usually 7, prominent; fresh water marshes. Glyceria

Glyceria grandis

• 12' Nerves of the lemma converging toward the summit.

Bromus latiglumis

• 14. Lemmas tapered to a point, usually awned or sometimes awn-tipped; sheaths of the leaves are open.
• 15. Plants annual. Vulpia
• 15' Plants perennial. Festuca
• 14' Lemmas broader, or sometimes tapered then awned from a bifid apex; sheaths of the leaves closed, at least in the lower half.
• 16. Spikelets large, mostly more than 15 mm long; lemmas often awned from a bifid apex, or nearly awnless. Bromus
• 16' Spikelets small, mostly less than 10 mm long; lemmas awnless. Poa
• 4' Lemmas 3-nerved, the nerves usually prominent.
• 17. Spikelets 2- or 3-flowered, rarely 5- or 6-flowered in Redfieldia and Munroa.
• 18. Inflorescence small, reduced, hidden among sharp-pointed leaves. Munroa squarrosa

Munroa squarrosa

• 18' Inflorescence not concealed, or only partially so.
• 19. Lemmas broad, truncate, the nerves parallel; plants decumbent and rooted at the nodes. Catabrosa aquatica

Catabrosa aquatica	Catabrosa aquatica	Catabrosa aquatica

• 19' Lemmas lanceolate, acute or acuminate, the nerves converging towards the apex; plants erect.
• 20. Callus of the floret densely silky-pilose. Redfieldia flexuosa

Redfieldia flexuosa	Redfieldia flexuosa	Redfieldia flexuosa

• 20' Callus of the floret glabrous. Muhlenbergia

Muhlenbergia sp

• 17' Spikelets (5-) 6- to many-flowered, as few as 5 in some Eragrostis curvula and Tridens muticus.
• 21. Lemmas with glabrous or scaberulous lateral nerves, awnless; glumes 0.5-2.5-(2.8) mm long. Eragrostis

Eragrostis pectinacea	Eragrostis pectinacea

• 21' Lemmas conspiculously long-hairy along the nerves, at least below, awned; glumes 3-8.5 mm long. Tridens muticus

Tridens muticus	Tridens muticus

Group 4

• 1. Plants dioecious (staminate and pistilate flowers on different plants) or monoecious, the sexes very dissimilar, the pistillate inflorescence superficially resembling Sitanion with its long awned lemmas and the staminate inflorescence with awnless lemmas; Kane county. Scleropogon brevifolius

Scleropogon brevifolius

• 1' Plants dioecious or monoecious.
• 2. Lemmas 3-nerved; spikelets 4-18-flowered.
• 3. Spikelets 4-flowered, the lower 2 sterile, the third fertile and the fourth reduced to a rudiment; lemmas deeply 3-lobed. Blepharidachne kingii

Blepharidachne kingii	Blepharidachne kingii

• 3' Spikelets 5- to 18-flowered, all but the terminal floret fertile; lemmas not deeply 3-lobed, except in Erioneuron pilchellum.
• 4. Panicle elongate and somewhat open, (4)-6-15 cm long; leaves not crowded at the base. Tridens muticus

Tridens muticus	Tridens muticus

• 4' Panicle short, compact, ovoid or oblong, 1.5-4-(8) cm long; leaves crowded at the base. Erioneuron
• 4'1. Panicles usually exceeded by a fascicle of leaves; lemmas 2.5-4-(5) mm long, deeply cleft; plants becoming stoloniferous. Dasyochloa pulchella = Erioneuron pulchellum

Dasyochloa pulchella	Dasyochloa pulchella	Dasyochloa pulchella

• 4'1' Panicles exserted; lemmas 4-7.5 mm long, not deeply cleft; plants not stoloniferous. Erioneuron pilosum

Erioneuron pilosum	Erioneuron pilosum	Erioneuron pilosum

• 2' Lemmas 5- to 11-nerved (sometimes 3-nerved in some Helictotrichon and Holcus).
• 5. Lemma divided into 9 plumose awns. Enneapogon desvauxii

Enneapogon desvauxii	Enneapogon desvauxii

• 5' Lemma with a single awn or awnless.
• 6. Awn of the lemma from the apex, between 2 lobes or absent.
• 7. Lemma awned.
• 8. Awn of the lemma arising between two lobes.
• 9. Sheath margins united to near the throat; panicles (8)-10-15-(20) cm long; awns 10-24 mm long. Bromus berteroanus = Bromus trinii

Bromus berteroanus

• 9' Sheath margins free to the base; panicles 1-6-(9) cm long; awns 3-10-(12.5) mm long.
• 10. Awn conspicuous, flat, bent; lemmas 6-15 mm long. Danthonia
• 10' Awns minute, nearly obsolete, only visible with magnification; lemmas small, 1.5-2 mm long; (Schismus arabicus can be distinguished from Schismus barbatus by its lemma with pubescence across the back and longer, acute lobes). Schismus barbatus

Schismus barbatus	Schismus barbatus	Schismus barbatus

• 8' Awn of the lemma arising nearly imperceptibly from a narrow, acuminate, unlobed apex. Vulpia
• 7' Lemmas awnless or at most terminating in a mucro no more than 1 mm long.
• 11. Spikelets 18-30 mm long. Avena
• 11.1. Awns present on the first and second florets, stout and strongly geniculate; lemmas with brown hairs. Avena fatua
• 11.1' Awns lacking or present on the first floret only, short, straight or curved, not geniculate; lemmas glabrous to sometimes scabrous. Avena sativa

Avena fatua	Avena sativa

• 11' Spikelets 1.5-11 mm long.
• 12. Spikelets mostly more than 7 mm long, or if smaller, plants annual (Sclerochloa)
• 13. Plants stout, rhizomatous perennials, 10-15 dm tall. Scolochloa festucacea

Scolochloa festucacea

• 13' Plants low, tufted annuals, 0.3-2 dm tall. Sclerochloa dura

Sclerochloa dura

• 12' Spikelets mostly less than 7 mm long
• 14. Lemmas 1.5-2 mm long; glumes 4-5-(6) mm long ; (Schismus arabicus can be distinguished from Schismus barbatus by its lemma with pubescence across the back and longer, acute lobes). Schismus

Schismus arabicus	Schismus arabicus	Schismus arabicus
Schismus barbatus	Schismus barbatus	Schismus barbatus

• 14' Lemmas 2-6 mm long, or if smaller, the glumes 3 mm or less long.
• 15. First glume 1.5-4.5-(5) mm long; lemmas 2-5-(5.5) mm long.
• 16. Plants small, 0.3-2-(2.5) dm tall.
• 17. Glumes dissimilar, the first 1.5 mm long, the second 2.5-3 mm long; lemmas about 2 mm long; annuals of moist alcaline habitats in valley bottoms. Puccinellia simplex

Puccinellia simplex

• 17' Glumes subequal, 3-5 mm long; lemmas 3-5 mm long; perennials of alpine habitats. Poa suksdorfii
• 16' Plants (2)-2.5-6.5 dm tall.
• 18. Lemmas 3.2-5.2 mm long; glumes similar in shape, the second 3.2-5.5 mm long; spikelets disarticulating above the glumes. Koeleria macrantha

Koeleria macrantha	Koeleria macrantha

• 18' Lemmas 2-3-(3.2) mm long; glumes dissimilar, the first linear, the second oblanceolate to broadly obovate, 2-2.8-(3.2) mm long; spikelets disarticulating below the glumes. Sphenopholis
• 18'1. Second glume rounded and broadly obovate, 1/3 to 1/2 as wide as broad; panicle dense and spike-like. Sphenopholis obtusata

Sphenopholis obtusata	Sphenopholis obtusata	Sphenopholis obtusata

• 18'1' Second glume blunt to acute, oblanceolate, 1/6 to 1/3 as wide as broad; panicle loose. Sphenopholis intermedia

Sphenopholis intermedia	Sphenopholis intermedia	Sphenopholis intermedia

• 15' First glume and the lemmas 5-7 mm long. Graphephorum wolfii = Trisetum wolfii

Graphephorum wolfii	Graphephorum wolfii

• 6' Awn of the lemma dorsally attached.
• 19. Spikelets with 2 or more perfect florets, the reduced florets, when present, terminal in the spikelet.
• 20. Spikelets not large, the glumes 2-7.5-(8) mm long.
• 21. Awn of the lemma attached above the middle; lemmas (3.5)-4-9 mm long. Trisetum

Trisetum spicatum	Trisetum spicatum	Trisetum spicatum

• 21' Awn of the lemma attached below the middle; lemmas 1.7-4-(4.5) mm long. Deschampsia
• 21'1. Plants perennial; lemmas larger, 2.5-4-(4.5) mm long; awns 1.5-5-(6.5) mm long.
• 21'2. Panicle open, if narrow not more than 1/4 the length of the culm; blades flat or folded, 1-3-(5) mm broad; anthers 1.2-2.2 mm long. Deschampsia cespitosa

Deschampsia cespitosa	Deschampsia cespitosa	Deschampsia cespitosa

• 21'2' Panicle narrow; blades usually filiform, the basal leaves about 1 mm broad; anthers small, 0.3-0.7 mm long; N half of Utah. Deschampsia elongata

Deschampsia elongata	Deschampsia elongata	Deschampsia elongata

• 21'1' Plants annual; lemmas very small, 2-2.8-(3) mm long; awns (4)-5-7.5 mm long; Cache, Weber, Davis, Salt Lake counties. Deschampsia danthonioides

Deschampsia danthonioides	Deschampsia danthonioides	Deschampsia danthonioides

• 20' Spikelets large, the glumes 8-30 mm long.
• 22. Plants large annuals, (2.5)-4-19 dm tall; glumes 17-30 mm long; panicles open, drooping, 10-38 cm long. Avena
• 22' Plants small perennials, 0.8-1.8-(2) dm tall; glumes 8-11.5 mm long; panicles narrow, erect, 3-5-(7.5) cm long; alpine tundra in Daggett, Duchesne, Summit, and Uintah counties. Helictotrichon mortonianum
• 19' Spikelets with 1 perfect floret and 1 staminate floret.
• 23. Lower floret staminate and awned, the awn twisted, geniculate, excerted; upper floret perfect Arrhenatherum elatius var. elatius

Arrhenatherum elatius	Arrhenatherum elatius	Arrhenatherum elatius

• 23' Lower floret perfect, awnless; upper floret staminate, with a hooked awn. Holcus lanatus

Holcus lanatus	Holcus lanatus	Holcus lanatus

Group 5

• 1. Lemma indurate, awned, permanently enclosing the palea and caryopsis, the callus well developed.
• 2. Awn of the lemma 3-branched. Aristida
• 2.1. Plants annual; glumes unequal: the first (4)-5-9 mm long, the second 7–12 mm long; the central awn 6–16-(25) mm long. Aristida adscensionis
• 2.1' Plants perennial; glumes unequal: the first (4)-7–14 mm long, the second (8)-11–25 mm long. Aristida purpurea
• 2.1'1. Panicle with slender, often nodding, flexuous or sigmoid branches, the pedicels capillary, the panicles usually deep purple throughout; S California to Utah, Arizona, New Mexico, Kansas, Texas and Mexico; Utah: Washington, San Juan counties. Aristida purpurea var. purpurea
• 2.1'1' Panicle branches stiff, usually erect (rarely some with open or slightly nodding panicles in var. longiseta), the panicles usually more reddish.
• 2.1'2. Awns only 10-30 mm long; panicles 10-25 cm long; lemma gradually tapering into a slender, often twisted beak 5-6 mm long; California, nevada, Utah and south to Arizona, New Mexico, Texas and Mexico. Aristida purpurea var. nealleyi = Aristida purpurea var. glauca
• 2.1'2' Awns (20)-25-100 mm long; panicles 5-11 cm long; lemma generally with a shorter beak or nearly beakless.
• 2.1'3. Culms mostly 2-3 dm tall; leaves usually in a compact basal tuft; range of the species, but more common southward. Aristida purpurea var. longiseta
• 2.1'3' Culms mostly 3-5 dm tall; leaves more loosely distributed over the lower half of the culm; range of the species, but more common northward. Aristida purpurea var. robusta
• 2.1" Plants perennial; glumes subequal, 8–18 mm long. Aristida arizonica

Awn is 3-branched in Aristida purpurea

• 2' Awn of the lemma unbranched.
• 3. Awn deciduous, mostly less than 10 mm long, not twisted, or only very slightly, sometimes bent, rarely more than 3 or 4 times as long as the plump lemma; callus short, usually obtuse.
• 4. Awns 7-18 mm long with villous lemmas 2.7-5.5 mm long; sterile hybrids. Stiporyzopsis
• 4' Awns 2-7 mm long, up to 9.5 mm in Oryzopsis micrantha which has glabrous lemmas; fertile species.
• 5. Glumes 2.5-7.5-(8) mm long. Achnatherum/Oryzopsis

Oryzopsis hymenoides

• 5' Glumes (7)-7.5-10 mm long. Achnatherum webberi = Stipa webberi
• 3' Awn usually persistent, (10)-14-200 mm long, usually twisted, several to many times longer than the narrow lemma; callus sharp-pointed. Achnatherum/Hesperostipa/Pappostipa/Stipa

Stipa comata

• 1' Lemma not evidently indurate, usually not permanently enclosing the palea and caryopsis.
• 6. Glumes, at least the second, equalling or usually longer than the floret.
• 7. Spikelets disarticulating above the glumes.
• 8. Glumes abruptly short-awned from an obtuse apex, ciliate on the prominent keels. Phleum
• 8.1. Sheath of uppermost leaf typically inflated; panicles to 4-(5) cm long; awns usually averaging more than 1.5 (1.5-4.0) mm long; culms 1-5-(6) dm tall, not bulblike at the base. Phleum alpinum

Phleum alpinum	Phleum alpinum	Phleum alpinum

• 8.1' Sheath of uppermost leaf not regularly inflated; panicles often more than 4 cm long; awns usually averaging no more than 1.5 (0.6-2.0) mm long; culms 2-15 dm tall, typically bulblike at the base. Phleum pratense

Phleum pratense	Glumes short-awned in Phleum pratense

• 8' Glumes not abruptly awned, if awned at all.
• 9. Lemmas 1-nerved, awnless; ligules short, consisting of a short fringe of hairs. Sporobolus

Sporobolus contractus	Glumes not abruptly awned in Sporobolus contractus

• 9' Lemmas 3- to 5-nerved, awned or sometimes awnless.
• 10. Lemma awned from an entire or minutely cleft apex, the body of the lemma 3-nerved. Muhlenbergia
• 10' Lemma with a dorsal awn, or if awnless, 5-nerved; glumes exceeding the lemma.
• 11. Awn of the lemma less than 4.5 mm long or absent, or if longer, arising at or below the midlength of the lemma (in C. purpurascens); lemma membraneous.
• 12. Callus of the floret evidently bearded, the hairs more than 0.5 mm long; palea usually well developed; rachilla prolonged behind the palea. Calamagrostis
• 12' Callus of the floret glabrous to minutely bearded; palea often absent or at least poorly developed; rachilla not prolonged behind the palea. Agrostis
• 11' Awn of the lemma evident, more than 5.5 mm long, arising from just below the apex of the lemma; lemma firm to subindurate. Apera interrupta

Apera interrupta	Apera interrupta

• 7' Spikelets disarticulating below the glumes, the spikelets falling entire.
• 13. Glumes awned.
• 14. Lemmas 0.7-1.5 mm long; anthers small, 0.4-0.7 mm long. Polypogon

Polypogon interruptus	Polypogon monspeliensis	Polypogon viridis

• 14' Lemmas (1.2)-1.7-2.3 mm long; anthers 1.1-2.3 mm long. Phleum
• 13' Glumes awnless.
• 15. Lemma with short awn from the notched apex; panicle usually somewhat open. Cinna latifolia

Cinna latifolia	Cinna latifolia	Cinna latifolia

• 15' Lemma awned from the middle or below; panicle dense, cylindrical, spike-like. Alopecurus

Alopecurus carolinianus	Alopecurus carolinianus

• 6' Glumes shorter than the floret.
• 16. Glumes and lemma awned.
• 17. Spikelets disarticulating below the glumes, the spikelets falling in pairs, the lower spikelet sterile; first glume usually 2- (3)-awned. Lycurus setosus

Lycurus setosus	Lycurus setosus	Lycurus setosus

• 17' Spikelets disarticulating above the glumes, the spikelets all alike; glumes each with a single awn. Muhlenbergia
• 16' Glumes and lemma awnless.
• 18. Spikelets disarticulating below the glumes.
• 19. Panicles open to congested, but never spike-like, (2.5)-5-35 cm long; ligules membraneous, 1.5-8.5 mm long.
• 20. Glumes dissimilar, the first linear, the second broadly oblanceolate to obovate; ligules 1.5-3.5 mm long. Sphenopholis

Sphenopholis obtusata	Sphenopholis intermedia

• 20' Glumes subequal, semicircular; ligules 5-8.5 mm long. Beckmannia syzigachne

Beckmannia syzigachne	Beckmannia syzigachne	Beckmannia syzigachne

• 19' Panicles dense and spike-like, short, 0.7-4.5-(6.5) cm long; ligules of hairs, 0.2-1 mm long. Crypsis

Crypsis alopecuroides	Crypsis schoenoides

• 18' Spikelets disarticulating above the glumes
• 21. Callus of the floret bearded; spikelets 6.5 mm or more long Calamovilfa gigantea

Calamovilfa gigantea	Calamovilfa gigantea

• 21' Callus of the floret glabrous; spikelets 1-4.5-(5.5) mm long.
• 22. Lemma 1-nerved; fruit not a true caryopsis as the ovary wall and seed coat are not fused. Sporobolus

Sporobolus contractus	Glumes not abruptly awned in Sporobolus contractus

• 22' Lemma 3-nerved; fruit a true caryopsis.
• 23. Nerves of the lemma glabrous or scabrous.
• 24. Sheath margins united to near the throat; nerves of the lemma parallel, not converging toward the apex. Catabrosa aquatica

Catabrosa aquatica	Catabrosa aquatica	Catabrosa aquatica

• 24' Sheath margins free to the base; nerves of the lemma converging toward the apex. Muhlenbergia
• 23' Nerves of the lemma densely pubescent. Blepharoneuron tricholepis

Blepharoneuron tricholepis	Blepharoneuron tricholepis