A N F Keys
1 Clonal perennials 3.5−8+ m tall, having "woody," bamboolike stems arising from shallow rhizomes, major stems and rhizomes 15−35 mm diameter; blades 250−860 × 15−77 mm (including long-tapered tip); typically lacking inflorescences (380−550 × 80−150 mm); spikelets with 2 ± equal glumes + lemmas with awns .. Arundo donax [pics]
1' Plants < 2.5 m tall (to 4.1 m tall in Cortaderia selloana), lacking thick, bamboolike stems, major stems and rhizomes < 12 mm diameter
2 Perennial turfgrasses, matlike with strongly procumbent shoots and creeping rhizomes and stolons, often forming adventitious roots at nodes
3 Inflorescences typically absent (rare), mostly concealed at shoot tips by sheath of flag leaf but with long-exserted filaments 40−55+ mm long; leaf sheaths closed .. Pennisetum clandestinum [pics]
3' Inflorescences produced each growing season, clearly elevated above foliage; filaments < 2 mm long
4 Blades 10−50(−70) × 1−2.5 mm; ligule membranous and minutely ciliate; inflorescence an open, ovate panicle, typically with 1 branch per node with each having a greenish yellow pulvinus at the base; leaf sheaths open .. Muhlenbergia asperifolia [pics]
4' Blades 25−130 × 2−4.5 mm; inflorescence umbel-like with terminal, ascending to spreading branches or racemelike with spreading branches, with spikelets in 2 rows, lacking pulvinus
5 Ligule of erect hairs 0.2−0.5 mm long; panicle branches 4−5(−7), slender (0.5−1.1 mm diameter); glumes always 2 and typically < 2 mm long .. Cynodon dactylon [pics]
5' Ligule membranous, 0.5−1.5 mm long; panicle branches (1−)2(−3), > 3 mm diameter, if not umbel-like but instead racemelike, then branches to 11 and leaves much larger (P. dilatatum); glumes 1 or 2, dominant glume 2.5−3.7 mm long .. Paspalum (part)
2' Annuals or perennials of various forms
6 Inflorescence a conspicuously jointed "spike," with appressed spikelets permanently fused to rachis and at maturity rachis breaking into 1-spikelet segments
7 Halophytic annuals (salt marsh); blades 12−65 × 1−1.5(−3) mm; spikelets lacking awns, glumes 3.8−7.3 mm long; inflorescence often curved .. Parapholis incurva
7' Annuals of open habitat; blades 30−185 × 2−3 mm; fertile spikelets with long awns, glumes 8−9 mm long; inflorescence straight .. Aegilops cylindrica [pics]
6' Inflorescence not jointed, not breaking at each node into 1-spikelet segments
8 Halophytes inhabiting salt marsh
9 Plants erect, with shoots widely spaced and individually arising from intertidal mud; blades suberect and inrolled above midpoint, 135−270 × 8−15 mm; ligules densely ciliate, 1−2 mm long; florets bisexual .. Spartina foliosa [pics]
9' Plants mostly spreading and often matlike; blades short−100 mm long; ligules < 0.5 mm long and membranous; dioecious, most clones unisexual (rarely florets bisexual) .. Distichlis
8' Plants terrestrial (including coastal sand dunes) or occurring in freshwater habitats
10 Spikelets subtended by 1−many conspicuous bristles (modified branchlets)
11 Bristles falling with each spikelet at maturity, feathery at least below midpoint (plumose) .. Pennisetum
11' Bristles persistent on rachis, scabrous with short, upward-pointing (antrorse) or downward-pointing (retrorse) barbs .. Setaria
10' Spikelets not subtended by 1 or more bristles (modified branchlets)
12 Leaf sheath closed for at least 1 mm above node on all leaves or at least for most leaves on each shoot
13 Awns present on spikelets
14 Awns present on glumes and lemmas
15 Inflorescence with 1 type of spikelet
16 Inflorescence unbranched, having a tight set of 3 ± sessile spikelets at each node so inflorescence often appears to have 6 vertical rows of awned spikelets, at least some awns > 5 mm long .. Hordeum
16' Inflorescence branched, having 1 branch at each node along the main axis, having 1-sided clusters of spikelets and strongly keeled, asymmetric glumes, the awns short .. Dactylis glomerata [pics]
15' Inflorescence with 2 types of spikelets, a sterile spikelet and a fertile spikelet, with all spikelets oriented to 1 side; some glumes and lemmas lacking awns .. Cynosurus echinatus [pics]
14' Awns absent on glumes but present on lemmas
17 Spikelets oriented to 1 side and drooping, having a cluster of several spikelets at the tip of a branch (fasciculate), with the terminal spikelet fertile and awned and others sterile and lacking awns, breaking at the base of the cluster .. Lamarckia aurea [pics]
17' Spikelets not in clusters of fertile a terminal spikelet and sterile lateral spikelets
18 Spikelet with only 1 floret, breaking below glumes; lemma awn with prominent bend .. Alopecurus saccatus
18' Spikelet with 2 or more fertile florets, breaking above the glumes and between florets; lemma awns ± straight
19 Spikelets mostly with 2−5 fertile florets; glumes 5.5−6.2 mm wide; lemmas 2-toothed with awn between teeth 0.2−2.5 mm long .. Festuca arundinacea [pics]
19' Spikelets mostly with 5−9 fertile florets; glumes 6.5−12 mm long; lemmas not toothed and with awn arising at or just before tip, awn > 2.5 mm long .. Bromus
13'Awns absent on spikelets
20 Spikelets modified into bulblike structures (corms), and each shoot having a bulbous base .. Poa bulbosa subsp. vivipara
20' Spikelets not modified into bulblike structures (corm), and shoot lacking a bulbous base
21 Spikelet not compressed; lemma and upper glume ± same length; rudimentary floret = a sausage-shaped, inrolled lemma .. Melica
21' Spikelet compressed side-to-side; lemma > upper glume; rudimentary terminal floret not sausage-shaped .. Poa
12' Leaf sheath open but sometimes sheath of flag leaf closed
22 Glumes awned or with awnlike points
23 Lemma appearing 3-awned
24 Panicles having short lateral branchlets forming stalked spikelets; blades to 2 mm wide; lower glume short-awned .. Aristida
24' Spikelike panicle having 2 suberect sessile spikelets per node; blades 2.5−5 mm wide; glume with long arms, lemmas of fertile and sterile florets 1−3-awned and divided .. Elymus multisetus
23' Lemmas appearing only 1-awned or with awnlike tip (sometimes lemmas awnless in Triticum aestivum)
25 Leaves with lobes (auricles) at top of sheath; at least some awns on each inflorescence 5+ mm long
26 Inflorescence with only 1 spikelet per node, lax or nodding in fruit; glumes asymmetric; spikelets with fruits remaining attached to inflorescence .. Triticum aestivum [pics]
26' Inflorescence with at least 2 or more spikelets at some nodes, not lax or nodding in fruit; glumes awns or ± symmetric; spikelets breaking above glumes and between florets .. Elymus
25' Leaves without lobes (auricles) at top of sheath; awns of glumes and lemmas always < 3 mm long
27 Inflorescence branches umbel-like (digitate), 1-sided with 2 overlapping rows of spikelets on lower side and rachis ending in sharp point; spikelets breaking above glumes .. Dactyloctenium aegyptium [pics]
27' Panicle cylindric-lanceoloid to lanceoloid or narrowly ellipsoid, with short lateral branches and radial (not 1-sided); spikelets breaking below glumes .. Polypogon (part)
22' Glumes without awns or awnlike points
28 Robust, clump-forming perennials mostly > 120 cm tall (mature plants with inflorescences); large blades typically 350−1000+ × 12−33 mm
29 Glumes broad, strongly keeled and flattened + narrowly winged approaching tip; panicles cylindric to narrowly ellipsoid and flexible .. Phalaris aquatica [pics]
29' Glumes narrow and neither keeled nor flattened
30 Blades with razor-sharp cutting margins; dioecious, unisexual panicles plumelike and at anthesis partially covered by sheath of flag leaf, fully expanded 500−900 × 200−450 mm; lemmas 7.8−17 mm long including awn to 3 mm long .. Cortaderia selloana [pics]
30' Blades without cutting margins; panicles of bisexual florets on highly condensed branches, branchlets, and densely clustered spikelets, at anthesis fully exposed from sheath of flag leaf, 150−400+ mm long, stiff, and relatively narrow; lemmas 7−11 mm long without awn or with awn poorly defined .. Elymus condensatus [pics]
28' Plants low−150 cm tall; blades mostly < 400 mm long (to 600 mm long in escaped crop plants of Sorghum and Avena, and in Leptochloa)
31 Lemma awns present on some or all florets (0.2 mm long in Koeleria macrantha)
32 In fruit, lemma awns with at least 1 prominent bend (somewhat subtle in Bothriochloa barbinodis)
33 Fertile spikelet with only 1 floret; lemma often having a crown at top with an ascending ring of hairs and an awn 10+ mm long .. Stipa
33' Fertile spikelet with 2 or more florets
34 Plant with only 1 type of spikelet; glumes > lemma of the lowest floret; awn arising on back of lemma at or below midpoint; stem internodes hollow .. Avena
34' Plant with 2 types of spikelets in sets, a stalked, sterile or staminate spikelet and a sessile fertile spikelet having a sterile lower floret and a bisexual upper floret; glumes < lemmas; awn arising from tip of lemma; stem internodes solid and core white
35 Stem nodes with a conspicuous, dense ring of ascending soft hairs 1.5−5 mm long; inflorescence densely pilose; inflorescence at maturity breaking into segments of a branchlet axis, a stalked sterile spikelet and a sessile, fruit-bearing spikelet, the segment with long hairs to 8 mm long .. Bothriochloa barbinodis [pics]
35' Stem nodes glabrous to puberulent or short-strigose; inflorescence short-villous or with hairs to 1 mm long; either breaking into segments of branchlet axis, a stalked spikelet, and a sessile, fruit-bearing spikelet or not, but hairs typically < 1 mm long .. Sorghum
32' Lemma awns never with a prominent bend, typically straight, slightly curved, or flexuous
36 Inflorescence branches 1-sided with spikelets formed in 2 overlapping rows; spikelets sessile or nearly so
37 Spikelets with 5−9(−10) florets; lemma awn to 1.5 mm long, lemma maturing smoky white .. Leptochloa
37' Spikelets with 2 florets
38 Inflorescence umbel-like with 5−15 ascending branches; spikelets produced on lower side, each with the lower floret bisexual and the upper floret sterile; awns 5−7 mm long; ligule truncate and short-fringed, < 1 mm long .. Chloris virgata [pics]
38' Inflorescence racemelike with 5−15 spreading branches; spikelets produced in clusters of 3−5 on the outer faces of branches, each with the lower floret sterile and the upper floret bisexual; awns 0−40 mm long; ligules absent .. Echinochloa crus-galli [pics]
36' Inflorescence branches with alternate distichous spikelets, not 1-sided
39 Spikelet with only 1 floret
40 Plant forming 2 types of spikelets, highly modified cleistogamous panicles on the lower plant and open panicles on the upper plant; lemma awns of open panicles 10−22 mm long, usually purplish, and appearing feathery, of cleistogamous panicles ca. 1.5 mm long .. Muhlenbergia
40' Plant with 1 type of spikelet
41 Inflorescence compact and fusiform to cylindric, (20−)35−120 × 3−13 mm; subterminal lemma awns 3−5 mm long .. Gastridium phleoides [pics]
41' Inflorescence open, lax, and wispy, 170−350+ mm long with divergent lateral branches; terminal lemma awns 2.9−4 mm long .. Stipa miliacea var. miliacea [pics]
39' Spikelet with > 1 floret (sometimes a spikelet forms only 1 floret)
42 Plant forming 2 types of spikelets in sets, the stalked spikelet sterile with a vestigial glume (absent) and the sessile spikelet with the lower floret sterile and the upper floret bisexual .. Andropogon glomeratus var. scabriglumis
42' Plant forming only 1 type of spikelet
43 Inflorescence mostly unbranched, but spikelets sometimes held ⊥ to main axis via pulvini (Festuca microstachys); spikelets generally with more than 2 bisexual florets (1−18); glumes symmetric; lemma awns 0.2−15+ mm long
44 Glumes equal; palea with stiff hairs along keels conspicuous along sides of spikelet; stem nodes conspicuously pubescent .. Brachypodium distachyon [pics]
44' Glumes unequal or only upper glume present (Lolium); palea glabrous to puberulent or keel minutely scabrous; stems glabrous .. Festuca
43' Inflorescence branches during flowering held ⊥ main axis via green axillary pulvini; spikelets with 2 bisexual florets; upper glume slightly asymmetric; lemma awns 0.2 mm long; anthers pendent; pistil on short stalk .. Koeleria macrantha [pics]
31' Awns never present on spikelets
45 Inflorescence branches 1-sided with spikelets formed in 2 overlapping rows.
46 Spikelets on lower side and compressed side-to-side; spikelets breaking above glumes; glumes 2
47 Spikelet with only 1 floret; matlike perennials (turfgrass) spreading via shallow rhizomes and stolons; ligule of erect hairs 0.2−0.5 mm long .. Cynodon dactylon [pics]
47' Spikelet with 3−10 florets
48 Annual, ± emergent aquatic; 55−110 cm tall; inflorescence with 35−55 ascending to spreading branches; ligule membranous and acute, 2−5.5 mm long, often split and sometimes long-ciliate .. Leptochloa
48' Annual (perennial), weed of cultivated fields; inflorescence umbel-like with 2−7(1−12) ascending to erect branches but often 1 branch arising long on the axis; spikelet with 3−7 florets; ligule membranous and truncate, 1−2 mm long, jagged and short-ciliate .. Eleusine indica [pics]
46' Spikelets compressed top-to-bottom; spikelets breaking below glumes, having 2 florets with the lower floret sterile and the upper one bisexual; glumes 1 or 2
49 Annuals; inflorescence mostly umbel-like with spreading terminal branches to 1 mm diameter .. Digitaria
49' Perennials with rhizomes and often stolons; inflorescence umbel-like to racemelike with spreading branches ca. 3 mm diameter .. Paspalum (part)
45' Inflorescence lacking 1-sided branches, spikelets alternate distichous on 2 sides of the rachis
50 Inflorescence at anthesis entirely or almost entirely enclosed in inflated sheath of flag leaf .. Crypsis
50' Inflorescence at anthesis generally not covered or enclosed by sheath of flag leaf
51 Spikelets with 2 or more fertile florets
52 Glumes < the lowest lemma
53 Inflorescence open with wiry axes; lemmas as broad as long, inrolled on membranous margins, closely overlapping and horizontally spreading; spikelets nodding and deltate in outline .. Briza minor [pics]
53' Inflorescence without wiry axes, spikelets not nodding, and lemmas not horizontally spreading
54 Lemmas with 3 prominent veins; plants often having an axillary pulvinus at branches and branchlets in the inflorescence and glandular tissue or glands (shiny and yellowish) on axes .. Eragrostis
54' Veins of lemmas not prominent, and plants lacking pulvini in the inflorescence and glandular tissue on axes
55 Spikelets with (6−)8(−12) florets; lemmas lanceolate, 9.2−10(−12) × 1.4−2 mm .. Elymus (part)
55' Spikelets with (2−4)5−7 florets; lemmas linear to lanceolate or oblanceolate, 1.8−2.3 × 0.6−0.9 mm, notched at the tip .. Puccinellia distans [pics]
52' Glumes ≥ the lowest lemma; glumes 4−6.3 mm long; spikelet narrowly lanceoloid compressed slightly side-to-side, 5−6.8 mm long, generally 1 per node .. Schismus
51' Spikelet with only 1 fertile floret
56 Perennial bunchgrass of coastal sand dune cloning from deep, long rhizomes; ligule acuminate-triangular, 11−31 mm long (shorter on flag leaf); blades appearing cylindric (tightly inrolled) and tough, 120−500+ mm long; lemmas lanceolate, 12−15 mm long, with midvein extended at tip .. Ammophila arenaria subsp. arenaria [pics]
56' Plants not inhabiting coastal sand dune; ligule < 5 mm long; blades generally not cylindric or tightly inrolled unless severely water-stressed
57 Glumes broad, strongly keeled and flattened + narrowly winged approaching tip; panicles cylindric to narrowly ellipsoid and flexible .. Phalaris
57' Glumes mostly lanceolate, not strongly keeled flattened, or winged
58 Perennial bunchgrass along creek margins in canyon bottoms; blades long-acuminate linear and flat, 90−930 × 2−5 mm, becoming inrolled when water-stressed; panicle condensed and cylindric, 210−440 × 9−11 mm, with appressed lateral branches Muhlenbergia rigens [pics]
58' Panicles ± open having spreading lateral branches
59 Annuals; panicles ovoid, 130−270 × 70−300 mm; spikelet with a sterile lower floret and bisexual upper floret, breaking below the glumes, with achene firmly enclosed in hard lemma and palea .. Panicum capillare
59' Perennials; spikelets breaking above the glumes, and achene not enclosed in hard lemma and palea
60 Panicle with lateral branches of many different lengths especially spreading and reflexed; spikelet with 3 florets, 2 sterile and the upper floret bisexual, resembling a lobster claw with transverse ridges on the longest (middle) lemma, other lemmas having minute basal lobes; leaves with lobes (auricles) at top of sheath .. Ehrharta erecta [pics]
60' Panicle ± lanceoloid with mostly ascending lateral branches; spikelet with 1 floret; spikelet not shaped like lobster claw; lemma without lobes (auricles) at top of sheath
61 Glumes 1.2−1.6 mm long; spikelet breaking below glumes at base of stalk .. Polypogon (part)
61' Glumes 2−3.4 mm long; spikelet breaking above glumes .. Agrostis
The text of the above keys used with permission from
A Naturalist's Flora of the Santa Monica Mountains and Simi Hills, California
© Copyright
Barry A. Prigge and Arthur C. Gibson
2013