KEYS TO THE NORTH AMERICAN GENERA OF GRASSES. R.W.Pohl and K. L.Chambers

Transcription

1 ARTIFICIAL KEYS TO THE NORTH AMERICAN GENERA OF GRASSES R.W.Pohl and K. L.Chambers 1 CUlms 2-rnany meters tall, stiff-stemmed, often woody and lasting several years, from slender to 10 cm thick, foliage blades sometimes pseudopetiolate and borne only on branches; some species rarely blooming. Key 1, page 2 1 CUlms rarely more than 2 m tall, stiff or flexible, usually not woody, usually lasting only 1 year, foliage blades rarely pseudopetiolate, borne on main stems as well as branches; species blooming annually except under extreme growing conditions 2 Allor most of the seed-forming (fertile) spikelets hidden in spiny burs, bony rachis internodes, beadlike structures, detachable fascicles of hard bracts, or completely hidden in leaf sheaths, only the stamens and stigmas visible (note: in some "hidden" spikelets, 1 glume may be visible Key 2, page 3 2 Allor most of the fertile spikelets exposed 3 Leaf blades inverted, with diverging veins and slender pseudopetioles more than 5 cm long Pharus 3 Leaf blades not inverted, with parallel veins, not pseudopetiolate 4 Spikelets disarticulating above the glumes which remain attached to the rachis or pedicels, or both glumes apparently absent (note: florets disarticulating from a persistent rachilla in some species of Eragrostis and Neeragrostis) 5 Spikelets with a single fertile floret and no rudimentary or sterile florets Key 3, page 5 5 Spikelets with 2 -many florets, some of which may be reduced or sterile 6 Inflorescence of 1-many spikes or spike-like branches, or a raceme with always 1 spikelet per node Key 4, page 9 6 Inflorescence an open or dense panicle; spikelets pedicillate or subsessile but not arranged on unilateral spikelike branches (if raceme-like, then more than one spikelet at some nodes of the axis) Key 5, page 14 4 Spikelets disarti~ating below the glumes, at most a minute cupule remaining attached to the pedicel, or spikelets in a few genera not disarticulating at maturity 7 Spikelets falling as single units, without accessory structures Key 6, page 2S

2 Page 2 7 Spikelets falling in groups and/or with accessory structures attached (e.g., rachis internodes, pedicels, bristle-like sterile branches), or in a few genera, the spikelets remaining on the plant at maturity Key 7, page 31 XEYl Giant grasses, the culms 2-many meters tall, sometimes woody. 1 CUlms with solid, pith-filled internodes 2 Spikelets less than 2 mm long; leaves 3-10 cm wide; cultivated ornamental species. Thysanolaena-l- 2 Spikelets 3 mm or more long; leaves less than 3 cm wide It.I.I> A W" le.sj ""\'10 3 SpJ.kelets wj.th 1 fertj.le floret, disartj.culatj.ng below the ~p ""S.;(.,I.""~"" glumes; cultivated crop and native species saccharum Sfl"i.</,/-, """,t/:. ~r"{hfl J 3 Spikelets with 2-several fertile florets, disarticulating 1~l above the glumes; ornamental species, occasionally escaped and weedy 4 CUlms not leafy, the leaves mainly basal; leaf blades with inrolled margins ~elodesmos'" 4 CUlms leafy, the leaves evenly distributed or forming a fanshaped terminal cluster; blades flat or convolute 5 Plants dioecious; spikelets with 2 florets; lower leaves with disarticulating blades I upper leaves forming a fanshaped cluster at top of stem Gynerium-f8 5 Florets bisexual; spikelets with 4-8 florets; lower and upper leaves with persistent blades : Ne~aUdia'" 1 CUlms with hollow internodes 6 CUlms woody, persisting more than 1 year 7 Internodes flattened or grooved on alternate sides; most nodes with 2 branches; cultivated Phyllostachys 7 Internodes terete; nodes wi th l-many branches 8 Lower leaf sheaths persistent or tardily deciduous; true spikelets pedicillate, in panicles; native Arundinaria 8 Lower leaf sheaths soon deciduous; pseudospikelets clustered in fascicles or capitate heads; cultivated Bambusa

3 Page 3 6 CUlms stiff but not woody, usually dying after 1 year 9 Most of the leaves borne in a large basal rosette; plants dioecious; cultivated and escaped Cortaderia \'~ 9 Leaves evenly distributed along the culms; all florets bisexual or functionally sterile 10 Leaf blades strongly cordate-based; lemmas hairy; rachilla glabrous; cultivated and escaped. Arundo 10 Leaf blades narrow-based; lemmas glabrous; rachilla hairy; native '..Phragmi tes \90 KEY 2 Grasses with variously concealed, spiny, or highly modified spikelets. 1 Fertile spikelets l-many, almost wholly concealed within the upper leaf sheaths (staminate inflorescences exserted in Buchloe) 2 pistillate spikelets falling 3-5 together as a bur-like cluster, the florets concealed by enlarged, rigid, 3-1obed glumes; dioecious or monoecious, mat-forming species of the Great Plains Buchloe 2 Some or all spikelets bisexual, or if pistillate then not falling as bur-like clusters 3 Plants perennial, stoloniferous or rhizomatous 4 Spikelets subtended by bristles; florets bisexual; introduced lawn grasses, often escaped and weedy Penniseturn 4 Spikelets lacking bristles 5 Spikelets with 2 glumes and 1 fertile floret, occurring in triplets (1 sessile fertile one and 2 pedicelled sterile ones) enclosed in a boat-shaped leaf sheath; rare introduced species ApI uda Jfr 5 Spikelets with 0 glumes and (on pistillate plants) 2-5 florets, not in triplets; plants dioecious; native species of seashores, Gulf of Mexico and California...Monanthochloe 3 Plants annual, often much branched and mat-forming 6 Spikelets 1-flowered, disarticulating above or below the glumes, the caryopsis often later falling free; lemmas glabrous C~sis

4 Page 4 6 Spikelets 3- or 4-flowered, disarticulating above the glumes and between the florets; lemmas with tufts of hair on the margins Munroa 1 Fertile spikelets usually many, borne on exserted.inflorescences 7 Inflorescence a bristly spike-like or racemose panicle, the spikelets concealed by straight or hooked spines or bristles 8 Spikelet clusters covered with usually hooked spines arising from enlarged glumes Tragys 8 Spikelet clusters covered with usually straight spines or bristles not arising from glumes 9 Spikelets bidden inside spiny burs, the spines straight, retrorsely barbed, fused into a cup-like bur Cenchrus 1~O 9 Spikelets +/- hidden by a tuft of smooth or plumose bristles, these not fused to form a bur Pennisetum 7 Inflorescence not bristly, the spikelets not surrounded by spiny structures 10 Inflorescence an unbranched spike bearing detachable fascicles of rigid, flat bracts concealing the spikelets; rachis zig-zag Anthep;hcra + ~ i1 10 Inflorescence not bearing detachable fascicles 11 Plants stoloniferous or rhizomatous; culms 1-3 dm tall; spikes solitary, club-shaped, breaking transversely; spikelets bisexual, + / -embedded in 2 or 4 rows on one side of the corky rachis; cultivated for turf and lawns, frequently escaped Stenota~hrum 11 Plants cespitose or rhizomatous, without stolons; culms dm tall; spikelets unisexual 12 Pistillate spikelets borne in solitary, pedunculate, bony, spherical beads {modified leaf sheaths}, only the stigmas and a short spike of staminate spikelets protruding from each bead C.Qix 12 pistillate spikelets several to many, borne in a bony segmented spike, or concealed within sheaths.on a cob ~3 Staminate and pistillate spikelets borne together in terminal spikes, the pistillate ones enclosed (except for ~ glume) in bony, cylindrical rachis internodes; rachis flattened distally, bearing numerous pairs of staminate sp~kelets; nat~ve spec~es..~~~~~~~.. T...'T' ; Y"\~~""""" "'\.~O

5 Page 5 13 Staminate spikelets in a terminal panicle or tassel; pistillate spikelets concealed by leafy sheaths on axillary spikes or cobs; cultivated..z.e.g, 3 1 Rachilla prolonged behind the palea as a slender bristle, or (in Phalaris) 1 or 2 small neuter lemmas present at the b~l.se of the conspicuous fertile one 2 Lemma awnless or mucronate 3 Inflorescence of digitately arranged, l-sided spikes ~:nodon 4 Lemma obscurely' veined; 1 or 2 small, often hairy, ster:ile lemmas present externally at base of fertile 1 Phalari~..("!S 4 Lemma 3- or 5-veined, the veins sometimes obscured by pu~lish pigmentation 5 Lemma 10 rom or more long, with abundant straight callu~; hairs i leaf blades narrow, involute i rhizomatous beach grasses of temperate zone AmmOJ;2hila 5 Lemma 7 tmn long or less; leaf blades flat or involute; callus hairs few or none 6 palea almost.as large as lemma, keeled along 1 prominent vein; leaf bliades up to 14 mm wide; arctic forest and tundra grasse:; Arctag:rcsti~+ 6 Palea shorter and more membranous than lemma, faintly 2- veined; leaf blades 4 mm wide or less; not limited to arctic regions Aqrostis 2 Lemma with a terminal or dorsal 3'L"\ 7 Glumes comparatively well developed, sometimes awn-like 8 Inflorescence a spike with 2 spikelets per node; glumes 4 per node, awn-lj.ke, 5-10 cm long.. Taeniat:herum fl..,m...j f!~';j

6 Page 6 8 Inflorescence an open or contracted panicle 9 Inflorescence a dense, plumose-bristly, egg-shaped tuft 9 Inflorescence open or contracted, never plumose-bristly '" La~rus 10 Inflorescence a dense, cylindrical, spike-like panicle; glumes bulging and sack-like at base Gastridium J~~ 10 Inflorescence not a dense, cylindrical, spike-like panicle; glumes not sack-like at base 11 Lemma usually bearing a conspicuous tuft of hairs on the callus; rachilla hairy; awn borne on back of lemma; perennials 12 Lemma with few or no hairs other than on callus; numerous native species Calamagrostis ~~l1 12 Lemma densely pubescent on lower half as well as on callus; 1 introduced species, mainly in California Aqrostis >~"'\ 11 Lemma without a conspicuous tuft of hairs on the callus; rachilla glabrous or hairy; awn subterminal; annuals 13 Inflorescence a spreading or contracted panicle..apera ~33~ 13 Inflorescence a bilateral spike Scribneria 1 Rachilla not prolonged behind the palea 14 Lemma rigid at maturity, cylindrical or egg-shaped, sometimes needle-like, not keeled (opposite choice on page 8) 15 Lemma awnless or with a short, fragile awn 16 Lemma egg-shaped, hairy, bearing a fragile,,often earlydeciduous awn Achnatherum ~ ~'Z.t's/Ji, Lemma dorsally compressed, smooth, shining, awnless.milium <"r1~ 15 Lemma with a persistent terminal or subterminal, sometimes twisted or geniculate awn 17 Awns 3, the lateral 2 sometimes vestigial; junction of awns with lemma not marked by a line (joint) Aristida ~ ~\bo 17 Awn 1, its junction with the lemma usually marked by an evident line (joint)

7 Page 7 18 Lemma margins involute, clasping the prominent keels of the palea; palea tip projecting from between the tops of lemma margins Piptocha~tium 18 Lemma margins flat, sometimes overlapping; keels of palea not prominent; palea either completely concealed or exposed most of its length 19 Lemma margins strongly overlapping; palea glabrous 20 Tip of lemma set off from the awn by a line of demarcation; ligule membranous, sometimes hairy at the 1.T~~.,.~"~ '" 1~' corners ~~=~ ~= ~ ~~ -.~ ~'1~ 20 Tip of lemma tapering imperceptibly into the awn with no line of demarcation; ligule a fringe of hairs or short, fringed membrane Aristida 19 Lemma margins not overlapping or only weakly so; palea usually pubescent 21 Callus 2-6 rom long, sharp; awn rom long Hes~erosti~a 21 Callus mm long, rounded to acute or sharp; awn 1-80 mm long 22 Lemma margins united at base, widely separated abov'e at maturity; floret somewhat dorsally compressed; callus glabrous or only sparsely pubescent Pi~tatherum 22 Lemma margins not united at base, usually partially overlapping at maturity; floret terete or laterally compressed; callus distinctly pubescent 23 Leaves appearing strictly basal; leaf blades mm wide; plants of wet alpine and subalpine meadows Ptila~ostis~ 23 Leaves rarely appearing strictly basal; leaf blades mm wide; plants not of wet alpine and subalpine meadows 24 Glumes less than 4 times longer than wide, with 6-10 veins; lemma always pubescent; palea as long as the lemma, glabrous O~zopsis 24 Glumes usually 4 or more times longer than wide, acute to acuminate, with 1-5 veins; lemma pubescent or glabrous; palea often shorter than the lemma + ' Achnath~rum ~ { I f~

8 Page 8 14 Lemma flexible at maturity, membranous; floret usually laterally compressed, often distinctly keeled 2S Inflorescence of l-several slender spikes or spike-like branches 26 Inflorescence of spikelike racemes terminating the numerous branchlets of a panicle; glumes absent Leersia 26 Inflorescence not a branching panicle of spikelike racemes; glumes present 27 Spikes several, racemose along a central axis or digitate at the culm apex 28 Spikes digitately arranged ~odon 28 Spikes racemoselyarranged 29 Spikes slender, elongated, strongly divaricate from the spirally curved rachis; keels of palea not ciliate Schedonnardus 27 Spikes solitary, terminal 30 Spike recurved, strictly unilateral; palea ciliate; ligule hairy Microchloa 30 Spike erect, not unilateral; palea not ciliate; ligule membranous Mihora Jtt 25 Inflorescence an open or contracted panicle 31 Glumes absent or much reduced in relation to lemma 32 Margins of upper leaf sheaths fused for 1/2 their length or morej spikelets not strongly compressedj native species of arctic and alpine regions Phi~~siaJft 32 Margins of leaf sheaths overlapping; spikelets strongly laterally compressed 33 Two subulate glumes (sometimes interpreted as sterile lemmas) present below the fertile lemma; cultivated crop, sometimes escaped O~za 33 Glumes (sterile lemmas) absent; native species, not cultivated Leersia S'$~ 31 Glumes well-developed, shorter than or exceeding the lemma

9 Page 9 34 Floret bearing a conspicuous tuft of hairs more than 1 mm long on the callus; lemmas awnless.calamovilfa f>1'l.-"1 34 Floret with callus hairs none or less than 1 mm long; lemmas awned or awnless 35 Leaf sheaths with margins fused for 1/2 their length or more; species of arctic and alpine regions Phip;p;sia+ 3S Leaf sheaths with overlapping margins; widespread species 36 Inflorescence a cylindrical contracted panicle; glumes equal, truncate, keeled, the midvein protruding as a short awn Phleum \' J~7 36 Inflorescence not densely cylindrical, or if so, then glurnes awnless; glurnes various, sometimes blunt, erose 37 Ligule hairy; lemma I-veined; fruit gelatinous when wet; panicle sometimes +/- hidden in leaf sheath(s) 38 Spikelets strongly compressed and keeled; panicles head-like to ovoid or shortly cylindrical C~sis 38 Spikelets keeled or not; panicles open to dense but not head-like or shortly cylindrical S~orobolus 37 Ligule membranous; fruit not gelatinous when wet 39 Lemmas indistinctly 5-veined A~rostis 3Il'i 39 Lemmas 3-veined, usually conspicuously so 40 Veins pilose; lemmas awnless Ble~haroneuron 40 Veins not pilose; lemmas awned or awnless.muhlenbergia 1bl KEY 4 Spikelets disarticulating above the glumesi florets 2-manYi inflorescence of l-many spikes or spike-like branches, or a raceme with 1 spikelet per node 1 Inflorescence a raceme with always 1 spikelet per node (note: sometimes reduced to a single spikelet in depauperate plants) 2 pedicels evident, over 1 mm long 3 Margins of leaf sheaths fused well over 1/2 their length; glumes much shorter than first lemma Pl~uropQgon 1f1i'4

10 Page 10 3 Margins of leaf sheaths overlapping; glumes longer than to slightly shorter than first lemma 4 Lemmas awned from between 2 apical teeth or awned lobes 5 Lemmas with a horizontal band of tufted hairs above the callus R~idos~e~g~ 5 Lemmas lacking a band of tufted hairs above the callus Danthonia 4 Lemmas awned from the back 6 Leaf blades flat or folded, 1-6 rom wide, the adaxial surface not ribbed AY.emJ.la+ " c.\jt.t~t 6 Leaf blades convolute, 1-2 rom wide, the adaxial surface ribbed over the veins HelictotrichonJt, 2 Pedicels very short, less than 1 rom 7 Raceme bilateral; lemma nerves Plants perennial, or if annual then with glumes 5 mm or more long Brachypodium 7 Raceme unilateral; lemma nerves 3 Tri~~on 1 Inflorescence of l-many spikes or spike-like branches 9 Inflorescence a solitary, terminal spike or spike-like structure,\~ (if a raceme, then 2 or more spikelets per node) [opposite lead (, on p. 13] 10 Glumes absent; inflorescence dense, cylindrical, spike-like lemmas fan-shaped, gland-dotted; rare species of vernal pools in central California Neosta~fia~ 10 Glumes presenti inflorescence various; more widespread 11 Inflorescence unilateral, the spikelets all fertile and in two rows on one side of the rachis 12 Spikelets with 2 sterile florets below the perfect one; second glume dorsally awned... Ctenium ~2 Spikelets with no sterile florets below the perfect one; second glume acuminate or awn-tipped Bouteloua

11 2":5 'L~"1 Page Inflorescence bilateral, the spikelets in two files on opposite sides of the rachis 13 Plants annual; introduced weeds and crops 14 Inforescence with 2-3 spikelets at each node; glumes narrow, often awn-like 15 Spikelets 3 at each node, each with usually only 1 floret, the 2 lateral spikelets usually sterile except in some crop varieties Hordeum 15 Spikelets 2 at each node, each with 1 fertile and 1 sterile floret (or sterile floret vestigial) Taeniatherum 14 Inflorescence with 1 spikelet at each node; glumes wide to narrow, less often awn-like 16 Spikelets placed so that 1 row of lemmas has the midnerves towards the rachis I all but the terminal spikelet with only 1 glume Lolium,,~, 16 Spikelets placed so that lemma midnerves are turned 90 degrees from the rachis, all with 2 glumes 17 Glumes subulate, 1-veined, membranous..secale 17 Glumes oblong to ovate, 5-13 veined, coriaceous 18 Glumes rounded on the back with several prominent veins, not keeled dorsally or near the apex; weedy...aegilops 18 Glumes keeled on the back or near the apex by 1 or 2 prominent veins; crops or taxa cultivated for genetic experimentation Triticum 13 Plants perennial (except Brachypodium distachyon); introduced and native species 19 Spikelets placed so that 1 row of lemmas has the midnerves towards the rachis; all but the terminal spikelet with only 1 glume Lolium 19 Spikelets placed so that lemma midnerves are turned 90 degrees from the rachis, all with 2 glurnes 20 Inflorescence nodes with three l-flowered spikelets, the lateral 2 spikelets pedicelled, their floret reduced and sterile; rachis very fragile Hordeum

12 '.",,-'.. Page Inflorescence nodes with 1-8 spikelets; spikelets all alike, with more than 1 floret, the second floret sometimes sterile; rachis often not fragile at maturity 21 Inflorescence internodes mm long; spikelets 1 per node 22 Perennial; spikelets numerous, strongly divergent from h hi ~I'T"""'T'\""""""" Z ~ 0 t e rac s ~=~~~~~~ ~ e 22 Annual or perennial; spikelets 1-15, ascending Brach~odium 21 Inflorescence internodes 6-20 rom long; spikelets 1-many at each node 23 Most inflorescence nodes with more than 1 spikelet 24 Plants cespi tose i anthers usually less than 2.5 mm longi glumes flat and evidently 3-veined at midlength, or awnlike and more than 20 mm long I or absent EI ymus 24 Plants cespitose or rhizomatous; anthers 3-7 mm long; glumes usually subulate and less than 15 mm (flat and evidently 3-veined at midlength in a few rhizomatous species) 25 Rachis disarticulating at maturityi plants cespitosei glumes subulate Psathyrostachys 25 Rachis not disarticulating at maturity; plants cespitose or rhizomatous; glumes subulate or flat Le~s ~1,4r 23 Most inflorescence nodes with only 1 spikelet 26 Auricles absent; spikelets usually with a short but evident pedicel; introduced weedy species Brach~odium 26 Auricles often present; spikelets sessile; native and introduced, weedy or not ~" 27 Glumes acuminate, tapering from midlength or below, their midvein curved; blades glaucous, stiffly ascen d ~ng " Pasco~~. -Ao ~ p 27 Glumes truncate to acute, narrowing from above midlength, their midvein straight i blades various 1..1P

13 Page Glumes stiff, truncate to acute, the midvein prominent, scabrous in its upper portion Thino~yrum o;:qs","tl1'i "Sf) 28 Glumes flexible, acute, with hyaline margins, mid and lateral veins similar! " 29 Spikelets usually twice as long as the rachis!:. internodes, partially overlapping the spikelet ii.! ii ". directly above; base of culm more than 2 rom thick;, '0. blades usually flat; basal ligule 1-2 rom I El~S f)~'-"'~"1j~j. f> 29 Spikelets slightly longer than the rachis internodes, slightly overlapping the next spikelet on the i opposite side of the rachis; base of culm often less than 2 mm thick; blades usually strongly involute; 3D b t)~=,,~,,...=~= '; ~ ~ srpf",..- d 1- asa ~gu e.-mm.~o=~~~~~=~~~=l~~ { 9 Inflorescence of 2 or more spikes or spike-like structures 30 Plants low, mat-forming; spikes hidden among the clustered upper leaves Munroa 30 Plants usually not mat-forming; inflorescences exserted above the leaves 31 Fertile floret 1, accompanied by 1-several sterile florets 32 Inflorescence of 2 or more unilateral spikes borne at wellseparated nodes along a central rachis 33 Spikelets separate or slightly overlapping; spikes long and slender Gymno~Qgon'" 33 Spikelets closely pressed together; spikes long or short, relatively thick Bouteloua 32 Inflorescence of 2-several digitate or whorled spikes 34 Spikelets appressed to the rachis; awns usually present; lemmas straw-colored or gray; stems solid Chloris 34 Spikelets divergent; awns minute or absent; lemmas brown; stems hollow Eustachys 31 Florets several, all essentially alike and usually fertile 35 Inflorescence a panicle of slender spikes borne along a central rachis (spikelets sometimes short-pedicelled in Lei2tochloa and Vuli2ia)

14 r" Page Letmnas obscurely 5-nerved, awned, the--a-wn-4 Imn or--more l~ (except y. octoflora) Vul~ig 36 Lemmas distinctly 3-nerved, awnless or with awn more than 3.5 mm long (except Le~tochloa fascicularis) 'vir 37 Rachilla and callus of florets densely pilose; glumes about 1 crn long Trichcn~ura 37 Rachilla and callus +/- glabrous; glumes less than 6 rom long 38 Rachilla prolonged beside the upper floret, sometimes bearing a rudimentary letmna; Florida.Gymnop;ogon ~ 38 Rachilla not prolonged beside the upper floret; widespread Le~tochloa 35 Inflorescence of few, thick, usually digitate spikes 39 Rachis prolonged beyond the spikelets as a naked point; upper glume with a divergent dorsal awn Dact~loctenium 39 Rachis covered with spikelets to the end; glumes not awned Eleusine Lt,q KEYS Spikelets with 2-many florets; inflorescence an open or dense panicle (if raceme-like, then more than 1 spikelet at some nodes of the axis) 1 Florets unisexual, plants dioecious or pistillate only All SPI'~(.(..\-1 ""II ({"t-~1 v",'>,~"t,1 2 CUlms 2-5 m tall; leaves mostly basal; panicle cm long, plumose; cultivated ornamentals, becomming weedy when escaped Cortaderia 2 CUlms mostly less than 1 m tall; leaves distributed along the culm; panicle 1-30 cm long, not plumose; native grasses 3 Pistillate spikelets long-awned; staminate spikelets awnless Sclero~ogon 3 Spikelets of both sexes +/- alike, awnless or short-awned 4 Plants annual, the branches creeping and rooting at lower nodes; spikelets often tightly Clustered Neeragrostis-l- 4 Plants perennial, the branches creeping or erect; spikelets clustered or not

15 IrS Page 15 5 Plants rhizomatous and stoloniferous; lemmas with 3 prominent veins; palea coriaceous, enfolding the grain; southern Texas Allole~is~ 5 Plants principally rhizomatous; lemmas 5-11-veined; palea not coriaceous 6 Glumes 3-7-veinedi lemmas faintly 5-11-veinedi species of saline marshes Distichlis 6 Glumes 1-3 veined; lemmas S-veined; habitats rarely saline 7 Leaf-tips shaped like the prow of a boat, sheath margins united 2 cm or more at base ~ 7 Leaf-tips pointed, sheath margins free nearly to the base Leuco~oa + 1. Florets bisexual ~6':~,I,t. b(.(,,~~.1 Dr..,.'ft... ( r..:.,.~,'." ~~ J."'j"",,,,-', S{e"", fc,j /)1r- t-~"i..,.. r/ ~I~. 8 Glumes absent; inflorescence dense, cylindrical, spike-like; lemmas fan-shaped, gland-dotted, awnless; rare, in vernal pools, central California Neosta~fiaJtt 8 Glumes present (or if rarely absent, then the lemmas long-awned) 9 upper glume (excluding awn, if present) as long as or longer than the first lemma [opposite lead on p.19] q'- P ~ 10 Glumes widely spreading, rounded and cup-like, broadly. d ~ ; ~~ 11~ ~~~~~ rnembranous-marg~ne ~ 10 Glumes not widely spreading, variously shaped but not cuplike, margins membranous or not 11 Spikelets of 2 forms, sterile and fertile, intermingled 12 Sterile lemmas acute, awn-tipped; disarticulation in rachilla of fertile spikelets ~osurus flg~ 12 Sterile lemmas obtuse, awnless; disarticulation often in the inflorescence below spikelet cluster Lamarckia ~~ Spikelets all alike and fertile 13 Lower 1 or 2 florets sterile or staminate, differing +/- in appearance from the fertile one; upper floret bisexual; all florets usually falling as a unit 14 Lower florets reduced to minute scales at the base of the rigid, shining terminal floret Phalaris

16 It. Page One or more lower florets larger than the fertile one (upper rudimentary floret also present in Ble~haridachne) 15 Lemmas of sterile and fertile florets 3-veined, the veins extending into short, ciliate awns; desert species Ble~haridachne 1S Lemmas S-veined; awn 1, not ciliate; not desert species 16 Florets 2 or 3, the lowest one staminate; fertile upper floret(s) sometimes awned 17 Florets 2, disarticulating together, the lower one dorsally awned Arrhenatherum ~o~ 17 Florets 2-3, the lowest one terminally awned and persistent, the upper one(s} dorsally awned and disarticulating. Ventenata 110" i... "!~ f'((, ~~ 16 Florets consistently 3, the lower two sterile or staminate; fertile upper floret awnless 18 Glumes unequal, the lower much shorter than the upper i sterile lemmas awned Anthoxanthum 18 Glumes +/- equal; sterile lemmas awned or awnless 19 Lower 2 florets staminate; widespread native species Hierochloe 19 Lower 2 florets neuter; introduced species, California Ehrharta 13 Lower florets fertile, bisexual 20 Leaf sheaths with margins fused for 1/3 their length or more 21 Lemma veins S-many, often prominent; uppermost florets often rolled together into a club-shaped rudiment; widespread Me 1 i ca 21 Lemma veins 1-3, faint; uppermost florets separate, not rolled together; arctic species 22 Spikelets with 2-7 fertile florets, the upper ones exserted from the glumes Arctophila~ 22 Spikelets with usually 2 fertile florets, these not exserted past the second glume DupontiaJ+,

17 Page Leaf sheaths with overlapping margins 23 Plants 2-5 m tall; panicles large, plumose because of spikelet hairs; cultivated and escaped Arundc 23 Plants usually 1 rn or less; panicles not large and plumose 24 Lemmas 3-veined, the veins evident 25 Florets 3 or more 26 Panicles 5-35 cm long, open or elongate with appressed branches; blade margins not cartilaginous; palea not conspicuously pubescent between the keels; culms cm tall ~~ 26 Panicles 1-6 cm long; blade margins white, cartilaginous; palea conspicuously pubescent between the keels; culms 4-65 cm tall 27 Blades involute, without a distinct midrib; lemmas divided to near midlength... Dasyocl~loa 27 Blades folded, midrib distinct; lemmas divided :Less than 1/4 its length.. Erionel~ 25 Florets 2 i rare or extinct endemic of California coastal islands Dissanth~liYm-tP 24 Lemmas with 5 or more, sometimes faint, veins 28 Lemmas with 7 or more short awns 29 Florets disarticulating separately; panicle loose, not dense and narrow. c..q.1:~ 29 Florets disarticulating together; panicle dense and narrow 30 Florets 3; lemma awns 9, plumose Enneapc~ ~~r 30 Florets 3-6; awns more than 9, not plumose ~ ~appo~ho~ 1.1.) 28 Lemmas with a single awn or awnless, sometimes with a pair of elongated teeth lateral to the awn 31 Glumes 7-9-veined, rounded on back, spikelets mm long Avena 't,~i I 31 Glumes 1-S-veined, rounded or keeled; spikelets less than 20 mm long

18 Page Awns absent or minute and produced from the tip of a bifid apex 33 Panicles narrow, dense, the main axis +/- hidden by spikelets 34 Plants annual, often weedy; lemma tip +/- distinctly notched 35 Lemmas awnless or mucronate; glumes equal in width and length.. Schismus ~ 3S Lemma awn 1-3 rom; first glume narrower and sometimes shorter than the second Rostraria 34 Plants perennial, seldom weedy; lemma tip acute, awnless or the awn less than 1 mm Koeleria l cj( 33 Panicles not dense, the main axis visible 36 Plants rhizomatous j panicle well-branched, with many spikelets Scolochloa 36 Plants cespitose; panicle little-branched, racemelike, spikelets 15 or fewer Dffi~thoniQ ~O4 32 Awns well developed, usually geniculate 37 Awn arising between 2 apical teeth or awned lobes 38 Lemmas with a horizontal band of tufted hairs above the callus 38 Lemmas lacking a band of tufted hairs above the callus Danthonia Awn arising from the back or base of the lemma 40 Spikelets 1 om or more long, exclusive of awns 41 Leaf blades convolute, 1-2 mm wide, the adaxial surface ribbed over the veins Helictotrichon 41 Leaf blades flat or folded, 1-6 mm wide, the adaxial surface unribbed Avenula ~t.\;~~". 40 Spikelets less than 1 cm long I exclusive of awns

19 1.11 Page Awn with a slender, club-shaped upper part, the joint between upper and lower parts of the awn hairy-tufted co~e~horus~ 42 Awn not of 2 differing segments, or if so, not hairy-tufted, the upper part not club-shaped 43 Rachilla not prolonged beyond the upper floret; first rachilla internode short, the second floret +/- opposite the first one ~ 43 Rachilla prolonged beyond the upper floret, usually as a hairy bristle; first rachilla internode often longer, distinctly elevating the second floret 44 Awn attached above the middle of.the keeled lemma, or awn absent Tri setum 44 Awn attached at or below the middle of the rounded lemma 45 Leaf blades flat, 3-6 mm wide, rolled in bud;! ligules blunt Vahlodea It ': ()~J.!:tl,C"'tl""I 45 Leaf blades folded or rolled, 3 mm or less wide, folded in bud; ligules acute or acuminate Descha~sia ~'l 9/ Both glurnes shorter than the first lemma 46 Veins of lemma 3, usually conspicuous ~I.f " Lemmas long-ciliat~, bearing a recurved awn; plants 1-3 m tall, reedlike; introduced weedy perennial, Florida ; Ne~audia ~ 47 Lemmas long-ciliate or not, awnless to straight-awned or merely apiculate; plants mostly not over 1.5 m tall; native or introduced species 48 Lemmas with all 3 nerves projecting as slender awns 5-7 mm long; introduced ~cies of sandy soils, Texas....Trira~his~ 48 Lemmas awnless or only the midnerve projecting as a slender awn (2 lateral lo~s tapering to an acute tip in Tri~lasis am~ricana) I 49 Mature caryopsis enlarged, flask-shaped, exserted; spikelets coriaceous r Diarrhena 49 Mature caryopsis not enlarged and flask-shaped

20 Page 20 SO Primary branches of inflorescence rigid, sharply pointed, the secondary branches clustered along main axis; rare JL. introduced species Cladora~his." SO Primary branches of inflorescence not rigid and sharply pointed; mostly native species 51 Lemmas densely bearded only at very base, otherwise glabrous; plants tall, rhizomatous; panicles very open ~fieldia-l- 51 Lemmas not bearded at very base, or if so, then hairy above base as well; plants usually cespitose or mat-forming; panicles various 52 Palea densely ciliate-villous on upper half of keels Trip;lasis 52 Palea ciliate on keels or not, the cilia, if present, not limited to upper part of keels S3 Margins of leaf sheath fused for 1/2 their length or more 54 Lemmas blunt, with prominent veins and glabrous callus; florets 1-2; species not limited to arctic regions ~.abrosa ~ 54 Lemmas acute to obtuse, with +/- obscure veins, the callus lightly beardedi florets 2-manYi.species of arctic regions ArctophilaJt! 53 Margins of leaf sheath overlapping 55 Paleae hairy on the back between the nerves, the nerves ciliate; panicle contracted... Erioneuron 55 Paleae hairy only on the nerves, if at all; panicle open or contracted 56 Lowest culm internode swollen, persisting for several years; florets 2-5; lemmas and paleae glabrous; rare introduced perennial of marshy sites MoliniaJ+f 56 Lowest culm internode not swollen or persistent; florets 3-many; lemmas and paleae often ciliate on the nerves; native and introduced annuals and perennials, more widespread.i" 57 Lemma nerves glabrous,...eragrostis ~ 57 Lemma nerves pubescent, at least near the base Tridens

21 Page 21 46~Veins of lemmas 5 or more, rarely 1, often inconspicuous 58 Leaf sheaths with edges united more than 1/2 their length S9 veins of lemmas parallel; lemma apex mostly blunt, awnless; second glume l-nerved; culms not bulb-based Gl ~ceria (' ~ \ 59 Veins of lemmas parallel or converging; lemma apex acute, bifid, or awned; second glume mostly 3-5 nerved; culms sometimes bulb-based, 60 panicle of a few rigid, naked branches bearing tufts of subsessile spikelets at their tips; introduced forage species, often weedy Dact~l i s 19L 60 panicle not with tufts of subsessile spikelets; native or introduced species, weedy or not 61 Glumes papery, brownish or reddish, usually lacking any green tissue 62 Callus of lemmas glabrous; lemmas awned or awnless, the upper 2-3 lemmas often sterile and rolled-up together; culms often bu~-based. Melica 62 Callus of lemmas bearded; lemmas long-awned, the upper lemmas not rolled-up together; culms not bulb-based Schi zachne 61 Glumes more herbaceous, with some green tissue, for example along the veins 63 Lemmas awnless, obtuse to acute 64 Callus glabrous or with a tuft of crinkled hairs (web); tip of leaf blades often shaped like the prow of a boat; numerous species, not limited to arctic and subarctic regions ~ Callus bearded to almost glabrous, lacking a web of crinkled hairs; tip of leaf blades pointed, not boatshaped; 1 rhizomatous perennial species of arctic and subarctic regions Du~ontiaJ+t,1 ~ Lemmas usually awned from a bifid apex, or in a few species awnless and sharply acute or bifid Bromus f 1\ 58 Leaf sheaths with overlapping edges, rarely united near the base 65 Tall reedlike grasses; c~ms 1-3 m tall

22 Page panicles diffuse, finely plumose-hairy 67 CUlms with hollow internodes; widespread native species 67 CUlms with solid internodes Pl'lra9l1]i 68 Leaves mainly basal, the blades involute, about 7 rom wide; lemma awn 1-2 rom long; introduced in California ~~lodesmos Jtt 68 Leaves cauline, the blades flat, 3-23 rom wide; lemma awn 3 mm long; introduced in Florida Ne~aUdia~ 66 Panicles not at all plumose-hairy; panicle branches spikate, clustered at the nodes of the main axis Leymus 65 Grasses of small to moderate stature; panicles not finely plumose-hairy 69 Lemmas nearly circular in dorsal view, cupped and spreading at a right-angle from the rachilla, the apex awnless and rounded; glumes wider than long Briza 69 Lemmas elongate, awned or acute, not spreading at a rightangle from the rachilla; glumes longer than wide 70 Spikelets in groups in which some are sterile, manybracted, and usually persistent, and others are fertile, 2-3-flowered, with the florets disarticulating CYl'losurus 70 Spikelets all similar and fertile 71 Spikelets with 2 somewhat enlarged sterile 'lower florets which fall with the fertile one.ehrhart a 71 Spikelets without enlarged lower florets, although some lower florets may be sterile 72 Lemmas 7-15-veined, the veins distinctly evident tes 73 Veins 9-11, each prolonged as an awn or short point Cottea <fj 11'::!- 73 Veins various, not prolonged into awns 74 Lemmas dorsally awned ~hibr'omus ~ 74 Lemmas awnless

23 '?R Page Lemmas rounded on the back, pubescent in the lower half Vase~ochloa -I- 75 Lemmas strongly keeled, glabrous.chasmanthium -:U~.'.I,! ("J 72 Lemmas 5-7-veined, the veins sometimes faint, i.e. not well differentiated from background tissue 76 Veins of the lemmas parallel; lemmas + / -blunt, never awned 77 Veins 5, faint; lemmas often with a purplish or brownish band below the membranous apex Puccinellia It 77 Veins 7, prominent; lermnas green Torre~ochloa "" ~1'7crr:~ f"l/ 76 Veins of the lemmas converging near the apex (especially the marginal ones angling toward the midvein) i lemmas acute or awned 78 Spikelets strongly flattened, all short-pedicelled; lemmas spreading from the spikelet axis, distinctly keeled throughout Chasmanthium-::fJ\.11 f l1-i 78 Spikelets less distinctly flattened, not all shortpedicelled (except Vul~ia, Desmazeria); lemmas rounded, at least in the lower half if keeled abo've 79 LetmnaS distinctly awned 80 Awn dorsal on (fertile) lemmas 81 Plants annualj first lemma sterile and with a terminal awn Ventenata 81 Plants perennial (except Trisetum interruptum) i first lemma dorsally awned " i/1~'4tltut~~ N.~ (t..~.. 82 Lemmas awned at or just below the middle; introduced in Louisiana ~hibrornus Jtt 82 Lemmas awned from above the middle; widespread, 1..'T' 4 "'~+ -zq1 most y nat~ve.spec~es ~~~d=~~..(. 80 Awn terminal on lemmas 83 Annuals; culms 5-90 cm; anther 1, remaining inside I the floret; selfpollinating vulp;ia it.s1v(~ ~cf. v'vlp~ (',(1 83 Perennials; culms cm; anthers 3, emerging from the floret; outcrossing

24 ill Page Auricles present; ovaries glabrous; mature caryopsis a dh eren t t 0 pa 1ea T,..' u,-,.:..- ~..-- F~.st~ ~ 84 Auricles absent; ovaries pubescent; mature caryopsis free from palea Eestuca 79 Lemmas awnless, blunt to acute (rarely mucronate), the tip sometimes shaped like the prow of a boat 85 Rachilla disarticulating slightly below each floret, remaining attached as a minute stipe; pedice.ls short and thick Desmazeria Jf! 85 Rachilla disarticulating at base of each floz'et, not remaining as a stipe; pedicels usually slender 86 Rachilla prolonged beyond the upper floret as a hairy bristle 87 Plants perennial, cm tall; native species, lr widespread ~ Trisetum ~t 87 Plants annual, 5-40 cm tall; rare introduced species, Manitoba Rrerno~oa Jfr 86 Rachilla not prolonged beyond the upper floret, or if so, then not hairy 88 palea keeled along one prominent vein, almost as long as lemmai florets 1 or 2.~~~~Jtt 88 palea with 2 equal veins, not with a single keel; florets 2 or more 89 Glumes membranous, indistinctly veined, lacking green tissue i dioecious, rhizomatous perennial ~~.,.. 89 Glumes more herbaceous, with some green tissue, e.g. along the veins; rarely dioecious; habit various 90 Auricles present; mature caryopsis adherent to palea; leaf sheaths open Lolium ~ 90 Auricles absent; mature caryopsis free from palea; leaf sheaths open or partly closed :::;:a- 91 Tips of leaf blades and lemmas +/- shaped like the prow of a boat; sheaths partly closed ~ i1'\ ~

25 ;s;:.,. Page Tips of leaf blades and lemma pointed, not upturned like the prow of a boat; sheaths usually open KEY 6 Festuca Spikelets disarticulating from the plants whole and singly, without attached pedicels and/or rachis segments (note: upper florets simetimes falling separately in S~henopholis; caryopsis falling free in Coleant:hu~) 2 Submerged aquatic, the culrns rooted in mud, only the uppe:rleaves floating; inflorescence a raceme LUZiOlaJt! 3 Dwarf, rigid, moss-like plants of tropical seashores; inflorescence a single spikelet Monanthcchlc~ 3 Plants not dwarf and rigid; inflorescence of more than a single spikelet 4 Fertile inflorescence racemose; plants of dry hillsides 4 Fertile inflorescence paniculate; plants of wetlands ~izia~ 5 Staminate and pistillate spikelets in separate inflorescences; culms 5-40 cm tall LUziolaJt! 5 Staminate and pistillate spikelets borne in a 'single inflorescence; culms cm tall 6 Pistillate spikelets in an erect terminal cluster; staminate spikelets on spreading lateral branches Zizania 6 Pistillate and staminate spikelets mixed throughout tb.e panicle Zizania'~sis 1 Spikelets with at least 1 bisexual floret, sometimes with additional staminate or sterile florets 7 Glumes absent or reduced to a minute ridge at apex of the pedicel (in Zo~sia, 1 glume is present but large and resembling the lemma of a l-flowered glumeless spikelet) 8 Inflorescence spike-like, solitary, erect

26 Page 26 8 Inflorescence of seve~ral digitate racemes or a panicle~,; lemmas awnless 10 Spikelets strongly laterally compressed; plants usucllly rhizomatous J~eersia 10 Spikelets not strongly laterally compressed; plants c:espitose or stoloniferous 5$"8 11 Inflorescence a panicle; spikelets +/- cylindrical; no sterile lemma present; rare cespitose annual, introlduced in the Pacific Northwest region ~s!anthus 11 Inflorescence of :s:everal digitate racemes; spikelets dorsally compressed; lower sterile lemma present and falling with the fertile floret; rare stoloniferous perennial of Florida and Cuba Reima~'ochloa Jtt 7 One or both glumes or glume-like bracts present below tb.e fertile florets (see also Reimarochloa, lead #11, above) 12 Spikelets laterally compressed; florets 1-many"[opposite lead on p. 28] ~3 Margins of leaf sheaths fused for ~/4 their ~ength or more 14 Plants annual; culms rarely over 20 cm long; rachil:la joints thickened by each lemma; 1 introduced weed. ~~ochloa 1.4 Plants perennial; culms usually over 20 cm long; ral:hilla joints not evidently thickened; several native spec:i'es 13 Margins of leaf sheaths overlapping jmelica 15 Spikelets mm long, many-flowered, very strong:ly compressed laterally; rhizomatous beach.grass Uniola 15 Spikelets various, 1-several-flowered (if many-flowe~:t"ed, then not very strongly compressed) 16 Inflorescence of 1 or more unilateral spikes or rac~l~rnes 1. 7 Spike 1. j only upper glume evident, resembling the :lemma of a glurneless spikeletj lawn grass, occasionally ' f lt ' t ' '7:. escap:lng rom cu :L va :Lon.!i YS J.a

27 Page Spikes more than 1, often numerous; both glumes present 18 Spikelets circular in lateral view; glurnes equal and +/- concealing the floret Beckmannia 18 Spikelets narrowly ovate in lateral view; glumes unequal, the floret visible.s~artina ~O? 16 Inflorescence a panicle 19 Inflorescence densely silky with long reddish hairs covering the glurnes Melinis -I- 19 Inflorescence not silky 20 Florets 2 or more, some possibly sterile 21 Glurnes S-7-veined; lemmas 7-9-veined Schismus c'to 21 Glumes 1-3-veined; lemmas 5-veined 22 Ligule a line of hairs; florets 2-4; lemma of fertile lower floret mucronate, distal lemma (s) short-awned Fingerhuthia ~ 22 Ligule membranous; florets 2-3; lemmas awnless or the distal 1 subterminally awned 23 First floret bisexual, distal floret staminate or neuter, awnedi leaf blades villous to velvety pubescent Holcus ]os 23 Florets all bisexual; distal lemma awnless, or if awned then leaf blades not pubescent S~henopholis 20 Floret 1 24 Floret subtended by 2 glume-like bracts (sometimes interpreted as sterile lemmas) much shorter than the floret i crop species O~za 24 Floret subtended by glumes as long as or longer than the floret; native and naturalized species 25 Glumes with an awn 2 mm or more long Pol~ogon \' ~(, Glumes awnless (short-awned or apiculate in Beckmannia) 26 Lemma with an elongated exserted awn 27 Inflorescence a spike-like contracted panicle, spikelets crowded.alop@curus f ~~ ~

28 Page Inflorescence a narrow, open panicle; spikej.ets not crowded LimnodeaJff 26 Lemma awnless or with a short included awn 28 Spikelets circular in lateral view Beckmannia SDfJ 28 Spikelets ovate or lanceolate in lateral view 29 Panicle open, the branches not spikelet-bearing to the base; lemmas awnless or nearly so Cinna 29 Panicle dense, sometimes spike-like, the branches, if evident, bearing spikelets to the base 30 Lemmas 5-veined, dorsally awned; panicle elongate cylindrical. Alo~ecurus 30 Lemmas l-veined or veinless, membranous, awnless; panicles evidently branched or densely ovoid to elongate-cylindrical 31 Glumes evenly scabridulous, much exceeding the truncate, erose lemma; panicle evidently branched Pol ~ogon 31 Glumes scabridulous only on the midnerve, slightly exceeding the obtuse lemma; panicle compact, the branches not evident C~sis =- "t-\t..cl\., p41:1 12 Spikelets dorsally compressed; fertile floret 1, usually with a sterile or staminate floret below (which may be diffi~t to discern if florets are concealed within the glumes) 32 Glumes stiff or rigid, +/- equal, both longer than the delicate florets; spikelets 2 at each node of the racemes or panicle branches 33 Inflorescence a single, erect spike-like raceme; spikelets dimorphic, one of each pair staminate, awnless, persistent, the other bisexual, long-awned, deciduous Trach~Qgon 33 Inflorescence an open or contracted panicle with racemose branches i -spi~eelet:s Qxx Q.~~ 34 Inflorescence contracted, spike-like; spikelets awnless Im~erata 34 Inflorescence of numerous diverging racemose branches; spikelets awned or awnless... ~anthus 1"Z>1

29 Page Glumes membranous, the first shorter than the second or absent; lemma of fertile floret usually stiff or rigid; spikelets 1 or more per node, if in racemes 35 Inflorescence of 1 or more unilateral spikes or racemes [opposite choice on page 30] 36 Ligules absent; first lemma often awned Echinochloa 36 Ligules present; first lemma not awned (except in Qplismenus and some species of Eriochloa and Echinochloa) 37 Fertile lemma somewhat flexible, its margins thin and recurved over the edges of the palea Digitaria 37 Fertile lemma +/- inflexible, its margins rigid, recurved over and stiffly enclosing the edges of the palea 38 Both glumes awned ~lismenus~ 38 Glumes not awned (or only the second glume awned in some species of Eriochloa and Echinochloa) 3 9 ~ikelets with a protruding basal knob composed of the rachilla and abortive first glume.eriochloa 39 Spikelets without a protruding basal knob 40 Inflorescence of 1-several verticels of racemes; fertile lemma awned Allotero~sis-l- 40 Inflorescence not verticillate; fertile lemma awnless 41 Spikelets positioned so that the backs of fertile lemma and upper glurne are turned toward the rachis of the raceme 42 Fertile lemma smooth; first glume usually absent Pasp;al urn 42 Fertile lemma minutely roughened (rugose) with a pattern of transverse ridges; first glume present 43 Rachis of raceme terminated by a ~ikelet; leaf blades I cordate, ciliate on the lower margins with conical- I based trichomes Urochloa + :; (1.,,:(,'1' 43 Rachis of raceme proj ecting as a naked point; leaf blades not cordate, not ciliate pas~alidium-l- 41 Spikelets positioned so that the backs of fertile lemma and upper glume are turned away from the rachis of the raceme

30 t Page Lower glume well-developed, i.e., 3 bracts present below the minutely roughened (rugose) fertile lemma Brachiaria 44 Lower glume absent, i.e., only 2 bracts pres~~t below the smooth fertile lemma Axono~us ~ 35 Inflorescence a panicle of more or less randomly disposed spikelets, the panicles varying from loose and well-.branched to compact and spike-like 45 Fertile lemma minutely roughened (rugose) with a pattern of transverse ridges i spikelets not subtended by bristles Br'achiaria 45 Fertile lemma smooth or minutely bumpy I but if transversely rugose I then some or all the spikelets subtended by bristles 46 Foliage sticky-hairy, covered with aromatic glandular hairs Mel ini s + 46 Foliage not glandular-hairy 47 Some or all of the spikelets subtended by l-many stiff bristles Setaria 47 None of the spikelets subtended by bristles 48 Spikelets rotund, shiny black when mature, and p:laced obliquely on the pedicels. ]:'asiacis + 48 Spikelets not black and shiny, not oblique 49 Plants producing enlarged subterranean spikelets on the tips of slender rhizomes; species of sandy Atlantic coastal plain ~u~~-tp 49 Plants lacking subterranean spikelets 50 Glumes or sterile lemma awned; spikelets densely crowded; ligule absent I or in 1 species consisting of a dense line of yellowish hairs Echinochloa 50 Glumes and sterile lemma awnless; ligule present 51 Mature fertile lemma somewhat flexible, its margins thin and recurved over the edges of the palea S2 Spikelets densely pubescent i first glurne minute or absent; panicles contracted

31 Page 3J. 53 Spikelets +/- egg-shaped; panicle branches not resembling unilateral racemes Anthaenantia'" S3 Spikelets flattened, lanceolatei panicle branches resembling unilateral racemes Digitaria 52 Spikelets not densely pubescent; first glume minute to evident; panicle open or contracted 54 Inflorescence a dense, cylindrical panicle; first glume up to ~/2 the length of the spikelet '. H~enachne~ S~Cc.\O\tl~\~ 54 Inflorescence a diffuse panicle; first glume no more than 1/4 the length of the spikelet. Digitari~ 51 Mature fertile lemma +/- inflexible, its margins rigid, recurved over and stiffly enclosing the edges of the palea 55 upper glume inflated at base; fertile floret much shorter than the glume and sterile lemma.sacciolep;is 55 upper glume not inflated; fertile floret equal to the glume and sterile lemma..panicum 61& KEY 7 Spikelets falling singly or in groups of 2 or more; if singly, then with attached rachis internodes, pedicels, or bristles (in a few genera the spikelets do not disarticulate at maturity) 1 Pistillate spikelets falling 3-5 together as a bur-like cluster, their florets concealed by enlarged, rigid, 3-lobed glumes; 1 dioecious or monoecious, creeping, mat -forming species of the Great Plains Buchloe 1 Some or all spikelets bisexual, or if pistillate then not falling as bur-like clusters 2 CUlms breaking at the nodes to disperse cleistogamous spikelets which are enclosed in the attached leaf sheath Triplasis 61 Z 11 2 CUlms not breaking at the nodes to disperse cleistogamous spikelets 3 Inflorescence a dense, bristly, spike-like panicle; spikelets falling attached to a cluster of bristles (probably derived from sterile pedicels) P@nniseturn rl~

32 d.~~~~;,,",or.~ "lj s' ~tro uce spec~es ~d~~~~~~ ~ Page 32 3 Inflorescence not bearing clusters of sterile bristles, although glumes are bristle-like in some genera ~~ 4 Each inflorescence consisting of a single spike or s];>ikeraceme (note: an inflorescence terminates the culm, and addi tional inflorescences may terminate lateral branches which arise in the axils of culm leaves. Two racemes may be appressed to resemble a single terminal spike in I~chaemum) [opposite lead on p. 35] 5 Rachis disarticulating into individual internodes, each bearing l-several spikelets (or the entire spike disarticulating as a unit from the culm apex in some species of Aegilops and Erlemo~yrum) [opposite lead on p. 34] 6 Spikelets with 2-several fertile florets 7 Glurnes with tufts of short bristly hairs on their keels 7 Glumes without tufts of bristly hairs 8 Spikelets solitary at each node Das~yrum 9 Lemmas dorsally awned above middle, awn twisted or geniculate Gaudinia Jft 9 Lemmas awnless or with a straight terminal awn 10 Glumes subulate, 1-veined, membranous; lemmas longawned Secale 10 Glumes lanceolate to ovate, 5-13-veined, coriaceous; lemmas awned or awnless 11 Plants rhizomatous perennials Thinopyrum t:j5r,p '1".. 11 Plants annual 12 Spikes 4 cm or less long; spikelets crowded and widely spreading from axis of spike; glumes awnless or with a short, straight awn ~no~yrum 12 Spikes longer than 4 cm (excluding depauperate plants), or if shorter, then spikelets not widely spreading, and glumes with a long, often curved awn 13 Glumes rounded on the back with several prominent veins, not keeled dorsally or near the apex,7 weedy. d

33 Page Glurnes keeled on the back or near the apex by 1 or 2 prominent veins; crops or cultivated for genetic experimentation. Tri ticum 8 Spikelets more than 1 at each node; glu.~8 e~-",=~ ~ =='- wide- 14 Glumes 3-7 rom long, not bristle-like; lemma awns mm long Psathyrostachys 14 Glumes rom long, often deeply split and bristlelike; lemma awns mm Elyrnus 6 Spikelets with 1 fertile floret, sometimes with a sterile one above or below 15 Rachis thickened, the spikelets more or less embedded or tightly pressed against it (see also, Key 2, page 3) 16 Spikelets consistently in pairs, one of them sessi].e and bisexual, the other pedicellate (or sessile in Rottboellia) and sterile or vestigial; first glume indurate, as long as the floret 17 pedicels fused to internodes i glumes of fertile spikelet smooth Rottboellia ~ 17 pedicels free; glumes often transversely rugose Coelorachis 16 Spikelets principally sessile, bisexual, single or with a paired pedicelled spikelet at some nodes of the spike; first glume absent or membranous and less than 1/2 as long as the floret (both glumes equaling the florets in Para~holis) 18 Rachis conspicuously flattened, the spikelets more or less embedded on one side in 2 or 4 rows; lemma coriaceous; plants perennial, stoloniferous Stenota~hrum 18 Rachis not conspicuously flattened, the spikelets embedded on alternate sides; lemma hyaline to membranous 19 Glumes 2; spikelets broadside to the rachis Parap;holis 19 First glume missing from all but the terminal spikelet; spikelets.~~:~~~~~.~~.~~~.~~~~~..hainardia~ 15 Rachis not thickened, the spikelets not embedded or pressed against hollows in the rachis

34 Page Fertile spike:l.et spherical, black, pitted, awnj.e!ss ""'."""""""'.~~hl2a~ 21 Spikelets 3 per node 22 Glumes brist:le-like; lateral 2 spikelets pedic:elled and reduced or sterile, all lemmas straight-a~'i1ed; widespread ~reedy and native species... Hordeum 22 Glumes lance~l:)latej 1 sessile and 2 pedicelled spikelets all fertile, the lenunas geniculate-awnedj law:c grass of subtropical areas ~:)l~riasjfr 21 Spikelets 2 per node 23 Both spikelets sessile; glumes bristle-like, c:>ften deeply split; lemma long-awned El~s 23 One spikelet sessile, the other pedicel led and differing from the sessile one, staminate or ',estigial (or absent and represented by a pedicel only),; fertile letmna awned or awnless 24 Lemma of se:ssile, fertile spikelet awned, peci:lcelled spikelet uniawned 25 Awn 5-15 cm long, fertile spikelet with an e~:longated sharp callus at maturity ~~ro~o~on 25 Awn less t]:lan 3 ctn, fertile spikelet with a blunt callus at truaturity..schiza,ch~ium A~ I~ 5 ~ 24 Lemmas unawiled in the sessile and pedicelled spikelets 26 Spikelets +/- hairy; first glume acute or 2-awned at tip; pedicel led spikelet staminate; native s~)ecies of woodlands, prairies, and deserts El~~urus 26 Spikelets ~rlabrous; first glume truncate; pedicelled spikelet ve!stigial or none i introduced lawn grrass of warm climat:es, sometimes weedy S.I:.emochloa 5 Rachis not disarticulating, the spikelets or spikelet cl'u.sters falling from it 27 Spikelets covered with hooked bristles Tragys 27 Spikelets without hoclked bristles 28 Fertile florets seve:ral; spikelets laterally compressled

35 Page Spikelets 1 or 2 per node; glumes broad 34 Rachis flattened; apex blunt; sheaths strongly keeled StenQta~hrum 31 Spikelets laterally compressed, borne in triads at rachis nodes (go to first choice 35, below) 3S Inflorescence spike-like with a tight triad of spikelets at each node, or raceme-like with ~ short unilateral branch at each node; triads and branches falling entire, leaving the rachis naked 36 Inflorescence branches of several to many spikelets Bouteloua,!;lL

36 Page Spikelet clusters (fascicles) congested on the rachis, ascending, the rachis zig-zag.hilaria t. 37 Spikelet clusters loose, more or less spreading; rachis not distinctly zig-zag 38 Plants stoloniferous perennials; glumes narrow, acuminate, pubescent ~estecum~ 38 Plants annual; glumes broad, glabrous, the apex notched and bearing a slender awn AS"..g.QP:.Qg.Qn+ 35 Inflorescence a panicle or a digitate or racemose group of spike-like branches 39 Rachis and branches remaining intact at maturity, the spikelets or spikelet-groups falling from them or the entire inflorescence persisting 40 Spikelets falling individually from the branches, bearing all or part of the attached pedicel 41 Plants reed-like, dm tall; leaves mm wide, up to 60 cm long; cultivated ornamental.~~~~ 41 Plants less than 10 dm tall i leaves 8 mm wide at most 42 Glumes with tapering membranous tip; florets 2-sevleral 43 Lemmas dorsally awned above the middle 44 Plants annual; proximal and distal lemmas awned Trisetum 44 Plants perennial; usually only the distal lemma awned sphenopholis 43 Lemmas awnless 42 Glumes awned (awnless in. viridis); floret 1 Schismus P..Q.J_~ogon 40 Spikelets falling in groups or remaining on the inflorescence 45 Spikelets remaini~g on. the inflorescence; rare endemic 0: J. Owens Valley, Cal~forn~a ~Lllenia.,. 45 Spikelets falling from the panicle in groups 46 Inflorescence branches spikelike, racemosely arranged on the main axis, deciduous with spikelets attached at maturity rare introduced species J:I~~

37 Page Inflorescence paniculate, the branches not spike-like; nati ve or introduced sp,ecies 47 Panicle densely spike-like; spikelets each with 1 floret, falling in pairs; native perennial species L~curus 47 Panicle somewhat congested; spikelets falling in groups consisting of one l-flowered fertile spikelet and several many-bracted sterile ones; weedy introduced annual species Lamarckia 39 Rachis or branches disarticulating at maturity, the spikelets or spikelet groups separating and falling in~ividually 48 Fertile florets several; glumes shorter than florets; plants annual; rare introduced species in southern California CUtandia ~ 48 Fertile floret 1; glumes longer than and concealing the florets; annuals or perennials 49 spikelets laterally compressed, sometimes strongly keeled 50 Plants 1-3 m tall, cespitose; leaf blades to 140 cm long, folded; ~tivated species of warm climates SO plants low, creeping; leaf blades short, flat; widely distributed introduced species Veti veria ~ 51 Leaf blades broad, cordatej first glume with 5-7 equal veins, not distinctly keeled ArthraxonJfr 51 Leaf blades lanceolate, tapered to a narrow base; first glume keeled along 2 distinct dorsal veins 49 Spikelets dorsally compressed, not strongly keeled 0 Microstegium+ 52 Inflorescence a dense, feathery panicle cm long, the. spikelets surrounded by silky hairs. Saccharum ~LJ".1" ~~),("L" ~ ~~ IV" 11"«,, ':. t"~4bh~f-v""1 52 Inflorescence various, sometimes with silky hairs but then i smaller and not appearing feathery I 53 Rachis internodes and pedicels with a translucent central longi tudinal band or groove 54 Plants cespitose or s~~~~~~~~~~~~.~~~~~~~~:othriochloa -;,.A"A"'fO~OVl

38 Page Plants annuals, the culms decumbent, rooting and branching at the lower nodes.,euclasta Jfr 53 Internodes and pedicels lacking a translucent central longitudinal band or groove 55 Spikelets borne on numerous short branches each with 2-4 spikelet-pairs, or in solitary triads; inflorescence often with the appearance of a much-branched pm~icle 56 Glurnes of 2 lower spikelet-pairs enlarged, spathe-like; inflorescence of many spatheate clusters of spikelets Themeda + 56 Glumes of lower spikelet-pairs not enlarged and spathe-like; spikelets not in spatheate cluste~'s 57 Spikelets in triads terminal on peduncles of a racemelike panicle; 1 spikelet of each triad fertile, awned, its callus sharp-pointed, hairy.~~qgqn'" S7 Spikelets on short branches of an open, well-branched panicle; callus of awned fertile spikelets blunt, hairy or not. 58 Pedicellate spikelets present, awnless and staminate; cultivated plants or weeds.sorghum 7)1 58 Pedicellate spikelets absent (or rarely vesti'9'ial), only the hairy pedicels present; native speci,es """"""""""".~hastrum SS Spikelets borne on elongated racemose branches, ~=ach consisting of S or more pairs of spikelets 59 All spikelet pairs in the racemes alike (homogamous or heterogamous), 1 or both spikelets of each pair bisexual and usually awned 60 Inflorescence branches usually 2, more or less pressed together and resembling a single terminal spike Ischaemum 60 Inflorescence branches 2-many I not pressed together 61 Pedicellate spikelet reduced, neuter or staminate, awnless (raceme heterogamous) Andropogon 61 Pedicellate spikelet equal in size to the sess;ile one, fertile, awned (raceme homogamous)

39 Page Veins of first glume raised; glumes pilose throughout, wi th call us hairs about 1/4 the length of the spikelet; 1 species, grown for ornament S~odio~Qgon ~ 62 Veins of first glume not raised; glumes usually not pubescent except on the callus; callus hairs usually more elongated; several species, native and introduced '.'...Saccharum 59 Lower spikelet pairs on each branch staminate or neuter (homogamous), awnless, the upper spikelet pairs of the raceme heterogamous, the fertile spikelets awned 63 Awns glabrous; racemes single, paired, or subdigitate I Dichanthi urn ::; IJ,""("~~~~.,,,, f' f~' 63 Awns pubescent; racemes always paired, the members of each pair with unequal basal homogamous zones H~arrhenia Jtf