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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

POACEAE (Gramineae) GRASS FAMILY

James P. Smith, Jr., except as noted


Annual to woody perennial herb; roots generally fibrous. Stem: generally round, hollow; nodes swollen, solid. Leaf: alternate, 2-ranked, generally linear, parallel-veined; sheath generally open; ligule membranous or hairy, at blade base. Inflorescence: various (of generally many spikelets). Spikelet: glumes generally 2; florets (lemma, palea, flower) 1–many; lemma generally membranous, sometimes glume-like; palea generally ± transparent, ± enclosed by lemma. Flower: generally bisexual, minute; perianth vestigial; stamens generally 3; stigmas generally 2, generally plumose. Fruit: grain (rarely achene-like).
650–900 genera; ± 10550 species: worldwide; greatest economic importance of any family (wheat, rice, maize, millet, sorghum, sugar cane, forage crops, ornamental, weeds; thatching, weaving, building materials). [Barkworth et al. 2003 FNANM:25; Barkworth et al. 2007 FNANM:24] Generally wind-pollinated. Achnatherum, Ampelodesmos, Hesperostipa, Nassella, Piptatherum, Piptochaetium, Ptilagrostis moved to Stipa; Elytrigia, Leymus, Pascopyrum, Pseudoroegneria, Taeniatherum to Elymus; Hierochloe to Anthoxanthum; Lolium, Vulpia to Festuca; Lycurus to Muhlenbergia; Monanthochloe to Distichlis; Pleuraphis to Hilaria; Rhynchelytrum to Melinis. The following taxa (in genera not included here), recorded in California from historical collections or reported in literature, are extirpated, lacking vouchers, or not considered naturalized: Acrachne racemosa (Roth) Ohwi, Allolepis texana (Vasey) Soderstr. & H.F. Decker, Amphibromus nervosus (Hook. f.) Baill., Axonopus affinis Chase, Axonopus fissifolius (Raddi) Kuhlm., Coix lacryma-jobi L., Cutandia memphitica (Spreng.) K. Richt., Dinebra retroflexa (Vahl) Panz., Eremochloa ciliaris (L.) Merr., Eustachys distichophylla (Lag.) Nees, Gaudinia fragilis (L.) P. Beauv., Miscanthus sinensis Andersson, Neyraudia arundinacea (L.) Henrard, Phyllostachys aurea Rivière & C. Rivière, Phyllostachys bambusoides Siebold & Zuccarini, Rottboellia cochinchinensis (Lour.) Clayton, Schedonnardus paniculatus (Nutt.) Branner & Coville, Schizachyrium cirratum (Hack.) Wooton & Standl., Schizachyrium scoparium (Michx.) Nash, Themeda quadrivalvis (L.) Kuntze, Thysanolaena latifolia (Hornem.) Honda, Tribolium obliterum (Hemsl.) Renvoize, Zea mays L., Zizania palustris L. var. interior (Fassett) Dore, Zoysia japonica Steud. Paspalum pubiflorum E. Fourn., Paspalum quadrifarium Lam., are now reported for southern California (J Bot Res Inst Texas 4:761–770). See Glossary p. 30 for illustrations of general family characteristics. —Scientific Editors: James P. Smith, Jr., J. Travis Columbus, Dieter H. Wilken.
Unabridged references: [Hitchcock 1951 Manual grasses US, USDA Misc Publ 200; Clayton & Renvoise 1986 Kew Bull Add Series 13]

Key to Poaceae

1. Leaf blade base constricted above sheath, forming false petiole; stem woody ..... [PHYLLOSTACHYS]

1' Leaf blade base not constricted, not forming false petiole, forming open or closed tubular sheath; stem generally herbaceous

2. Spikelets enclosed in bristly to spiny, bur-like involucre ..... CENCHRUS

2' Spikelets not enclosed in bristly to spiny, bur-like involucre

3. Some or all florets modified into bulblets with conspicuous, awn-like tails ..... Poa bulbosa subsp. vivipara

3' Florets not modified into bulblets

4. Leaf blades, at least upper, generally stiff at maturity, sharp-pointed and conspicuously arranged in 2 vertical rows

5. Spikelets unisexual, plants generally dioecious; plants of salt marshes and moist alkaline sites ..... DISTICHLIS (2)

5' Spikelets bisexual; plants known only from sand dunes in Inyo Co. ..... SWALLENIA

4' Leaf blades generally soft, rounded to acute, but not sharp-pointed (except Blepharidachne, Munroa), not conspicuously arranged in 2 vertical rows (except Muhlenbergia asperifolia)

6. Leaf blade and sheath undifferentiated; stem internodes solid; ligules 0

7. Spikelets 2-ranked on inflorescence axis ..... ORCUTTIA

7' Spikelets spirally inserted on inflorescence axis

8. Plant glandular-sticky at maturity; inflorescence a dense, cylindric spike, generally fully exserted at maturity; spikelets dorsally compressed ..... NEOSTAPFIA

8' Plant not glandular-sticky at maturity; inflorescence club-shaped, often ± enclosed by leaves at maturity; spikelets laterally compressed ..... TUCTORIA

6' Leaf blade and sheath clearly differentiated; stem internodes generally hollow; ligules generally present

9. Basal or subterranean internodes swollen, bulb- or corm-like

10. Inflorescence spike-like, cylindric or ovoid, branches not evident; glumes winged ..... Phalaris aquatica

10' Inflorescence panicle-like, open with evident branches; glumes not winged

11. Sheath open; glumes ± enclosing florets; lower lemma awns bent, twisted ..... ARRHENATHERUM (2)

11' Sheath closed to near tip; glumes = lowest floret; lower lemma awns generally 0 or awns straight, untwisted ..... MELICA

9' Basal or subterranean internodes not swollen, not bulb- or corm-like

12. Robust perennial herb, generally 1.5–7 m; stem 0.5–3 cm diam, tough, hardened to woody, generally persisting; inflorescence terminal, often conspicuously plume- or fan-like ..... Group 1

12' Low annual to mid-sized perennial herb, generally < 1.5 m; stem generally < 5 mm wide, strictly herbaceous, generally dying back annually; inflorescence axillary, terminal, or both, but not conspicuously plume- nor fan-like

13. Plants generally < 15 cm; mature inflorescence not clearly exceeding leaves, often ± enclosed in upper sheath

14. Floret 1; lemma 1-veined ..... CRYPSIS

14' Florets 2+; lemma >= 3-veined

15. Lemma awn 0

16. Inflorescence subtended by 5–10 bristles; spikelets 1–2 mm; florets 2 ..... Pennisetum clandestinum

16' Inflorescence not subtended by bristles; spikelets 6–10 mm; florets 3–5 ..... SCLEROCHLOA

15' Lemma awns 1 or 3

17. Lemma 3-lobed, conspicuously ciliate; upper florets 3-awned ..... BLEPHARIDACHNE

17' Lemma 2-lobed or tapering to awn

18. Glumes 6–9 mm, > lemma; lemma 2-lobed ..... DASYOCHLOA

18' Glumes 2–4 mm, < lemma; lemma tapering to point ..... MUNROA

13' Plants generally >> 15 cm; mature inflorescence clearly exceeding upper leaves

19. Spikelets 1–2 per inflorescence

20. Glumes < lowest floret; awns (if present) not twisted, nor bent ..... Brachypodium distachyon

20' Glumes > lowest floret; awns twisted and bent ..... Danthonia unispicata

19' Spikelets few to many in a well-developed inflorescence

21. Spikelets subtended by 1+ bristles, sterile branches, or long, silky hairs > spikelet

22. Spikelets subtended by long, silky hairs from their bases, rachis joints, or pedicels

23. Spikelets dissimilar, sessile bisexual, stalked sterile ..... BOTHRIOCHLOA

23' Spikelets similar, bisexual ..... IMPERATA

22' Spikelets subtended by 1 or more generally stiff bristles or sterile branches

24. Bristles short-stiff-hairy ..... SETARIA

24' Bristles scabrous to long-ciliate

25. Inflorescence panicle-like, branches 2–7 ..... ANDROPOGON

25' Inflorescence spike-like, dense, cylindrical ..... PENNISETUM

21' Spikelets not subtended by bristles or by long, silky hairs

26. Glume and/or lemma bodies covered with long, silky hairs

27. Inflorescence dense, ovoid or oblong, head-like; spikelets 1-flowered ..... LAGURUS

27' Inflorescence open, branching evident; spikelets 2-flowered

28. Spikelets paired on one side of a slender rachis ..... Digitaria californica

28' Spikelets single on ends of short capillary branches ..... MELINIS

26' Glumes and lemma bodies glabrous to short-hairy

29. Glumes or lemma (perhaps only in a unisexual spikelet) with 3–9 awns or awn-like segments (lateral awns sometimes << than central 1)

30. Lemma awns 9, plumose ..... ENNEAPOGON

30' Lemma awns 0–3, not plumose

31. Lower glume with (2)3–9 awns or awn-like segments

32. Spikelets 1–flowered ..... Muhlenbergia alopecuroides

32' Spikelets 2–5 flowered

33. Annual; spikelets 1 per node ..... AEGILOPS

33' Perennial herb; spikelets 2(3–4) per node ..... Elymus multisetus

31' Lower glume awn 0 or 1

34. Spikelets 1-flowered ..... ARISTIDA

34' Spikelets 2–several-flowered

35. Inflorescence open, panicle-like; spikelets pistillate ..... SCLEROPOGON (2)

35' Inflorescence 1–many raceme-like or spike-like 1° branches; spikelets bisexual ..... BOUTELOUA

29' Glume or lemma awns 0–2

36. Spikelets generally dorsally compressed (cylindrical); florets 2, lower sterile or staminate, often reduced to sterile lemma, upper floret bisexual; glume and fertile lemma texture noticeably dissimilar; spikelets breaking apart below the glumes, falling singly or in pairs with segments of inflorescence axis attached ..... Group 2

36' Spikelets generally laterally compressed or cylindric; florets 1–many, if > 1, lower one(s) generally fertile, upper reduced and sterile; glume and fertile lemma texture generally similar; spikelets generally breaking apart above glumes and between florets or floret clusters

37. Plants bearing markedly dissimilar spikelets in the same or separate inflorescences

38. Spikelets unisexual ..... SCLEROPOGON (2)

38a. Terrestrial perennial herb to 20 cm; creosote scrubland ..... SCLEROPOGON

38a' Aquatic annual 1–1.5 m; cultivated fields and adjacent ditches ..... [ZIZANIA]

38' Spikelets bisexual or sterile

39. Inflorescence spike-like

40. Stem internodes solid; spikelets sessile ..... HILARIA

40' Stem internodes hollow; central spikelet sessile, laterals stalked (except in Hordeum vulgare) ..... HORDEUM

39' Inflorescence panicle-like, open to dense

41. Lemma awn 0; spikelets in groups of 7 (1 fertile + 6 sterile) ..... Phalaris paradoxa

41' Lemma awned; spikelets paired or in pendant clusters

42. Inflorescence panicle-like with drooping clusters of 1 fertile spikelet and 1–3 sterile ones; spikelet clusters falling as 1 unit ..... LAMARCKIA

42' Inflorescence head-like or cylindric, spikelets generally paired; spikelets falling separately ..... CYNOSURUS

37' Plants bearing similar spikelets, differing only in size and degree of maturity

43. Spikelets sessile or stalked on an unbranched central axis ..... Group 3

43' Spikelets attached to 1° or 2° branches (dissection may be needed to reveal branches)

44. Inflorescence a series of 2 or more digitate, raceme-like, clusters, or whorls of 1° branches ..... Group 4

44' Inflorescence much-branched, 2° or 3° branching evident

45. Spikelets 1-flowered ..... Group 5

45' Spikelets 2–many-flowered (sterile florets reduced to small scales or hairy, awl-like rudiments)

46. Spikelets 2–8 per node ..... ELYMUS

46' Spikelets 1 per node

47. Spikelets unisexual; plants dioecious

48. Leaf tips prow-shaped; lemma base with cottony or cobwebby tuft of hairs ..... POA

48' Leaf tips flat; lemma bases glabrous to scabrous

49. Plants rhizomatous; lemma glabrous, veins 9–11, inconspicuous ..... DISTICHLIS (2)

49' Plants densely tufted; lemma scabrous, veins (3)5(7) ..... Festuca kingii

47' Spikelets bisexual

50. Fertile florets 2+ (occasionally 1 in Dissanthelium)

51. Lemma veins generally (3)5–several, sometimes very faint ..... Group 6

51' Lemma veins 3, generally prominent (laterals sometimes near margins)

52. Glumes > florets; florets 2(3) — Channel Islands only ..... DISSANTHELIUM

52' Glumes < upper florets; florets 3–many

53. Lemma veins glabrous ..... ERAGROSTIS

53' Lemma veins hairy, at least below

54. Leaf blade margin white; lemma awn 0.5–2.5 mm; stigmas white ..... ERIONEURON

54' Leaf blade margin green; lemma awn 0; stigmas purple ..... TRIDENS

50' Fertile floret 1

55. Spikelet breaking below glumes; lower floret bisexual, awn 0; upper floret staminate, awned ..... HOLCUS

55' Spikelet breaking above glumes; staminate or sterile floret(s) below fertile one (sometimes << fertile and easily overlooked)

56. Fertile floret generally awned

57. Perennial herb; nodes green or straw-colored; spikelets breaking apart below lowest floret ..... ARRHENATHERUM (2)

57' Annual; nodes purple-black; spikelets breaking apart above lowest floret ..... VENTENATA

56' Fertile floret awn 0

58. Lower florets reduced to sterile lemma < 1/2 fertile floret ..... PHALARIS

58' Lower staminate or sterile florets >= fertile one

59. Spikelets straw-colored or brown at maturity; stamens 2–3; auricles 0 (except in Anthoxanthum aristatum, A. odoratum) ..... ANTHOXANTHUM

59' Spikelets green or purplish at maturity; stamens 3 or 6; auricles ciliate ..... EHRHARTA

Group 1: Robust perennial herb; stem generally 1.5+ m, 0.5+ cm diam

1. Stem much-branched above base ..... [PHYLLOSTACHYS]

1' Stem not branched above base (except inflorescence)

2. Leaves predominantly basal

3. Stem internodes hollow; spikelets unisexual (pls generally pistillate) ..... CORTADERIA

3' Stem internodes solid; spikelets bisexual ..... Stipa mauritanica

2' Leaves well distributed along stems

4. Inflorescence branches and spikelets glabrous

4a. Glumes 0 or vestigial - inflorescence branches unisexual, spikelets remaining intact until harvested ..... [ZIZANIA]

4a' Glumes present

5. Inflorescence spike-like (branched below) ..... Elymus condensatus

5' Inflorescence panicle-like ..... SORGHUM

4' Inflorescence branches and/or spikelets hairy

6. Stem internodes solid; spikelets paired, one or both stalked

7. Spikelets unequally stalked; inflorescence axis remaining intact at maturity ..... IMPERATA

7' 1 spikelet sessile, 2nd stalked; inflorescence axis breaking apart at maturity, segments with spikelets attached ..... SACCHARUM

6' Stem internodes hollow; spikelets 1 per node

8. Spikelet axis glabrous; lemma densely hairy ..... ARUNDO

8' Spikelet axis silky-hairy; lemma glabrous ..... PHRAGMITES

Group 2: Spikelets dorsally compressed, breaking apart below glumes; glumes and fertile lemma of dissimilar texture

1. Glumes leathery to hardened (at least in sessile spikelets), ± equal, 1 or both generally > upper floret (except awns); fertile and sterile lemmas generally translucent

2. Spikelets 1 per node, subtended by a hairy bristle ..... ANDROPOGON

2' Spikelets 2 or 3 per node, 1 sessile and 1 (2) stalked

3. Terminal spikelets per branch in 3s, 1 sessile and 2 stalked ..... SORGHUM

3' Terminal spikelets per branch in 2s, 1 sessile and 1 stalked

4. Inflorescence unbranched, raceme-like ..... HETEROPOGON

4' Inflorescence branched, panicle-like

5. Inflorescence internodes and spikelet stalks with a translucent longitudinal groove; lowest pair of spikelets per raceme fertile ..... BOTHRIOCHLOA

5' Inflorescence internodes and spikelet stalks without a translucent longitudinal groove; lowest pair of spikelets per raceme staminate ..... HYPARRHENIA

1' Glumes membranous, flexible, lower glume generally < upper (0), upper glume <= upper floret; sterile lemma membranous and resembling upper glume, fertile lemma leathery to hardened (membranous in Digitaria)

6. Spikelet subtended by a cup- or ring-like structure ..... ERIOCHLOA

6' Spikelet not subtended by cup- or ring-like structure

7. Ligule 0, at least on upper leaves ..... ECHINOCHLOA

7' Ligule present

8. Inflorescence a series of digitate or raceme-like branches

9. Fertile floret membranous, flexible at maturity ..... DIGITARIA

9' Fertile floret leathery to hardened, rigid at maturity ..... PASPALUM

8' Inflorescence panicle-like

10. Fertile lemma thin, flexible; lower glume minute or 0 ..... Digitaria californica var. californica

10' Fertile lemma ± thick, rigid; lower glume well-developed ..... PANICUM

Group 3: Inflorescence solitary, spike-like or raceme-like; spikelets sessile or stalked

1. Some or all spikelets stalked

2. Spikelets 3 per node, sessile and stalked (or only stalk remaining after upper spikelet has fallen); inflorescence spike-like

3. Stem internodes solid; auricles 0; central spikelet short-stalked, laterals sessile; glumes awned ..... HILARIA

3' Stem internodes hollow; auricles present or 0; central spikelet sessile, laterals stalked; glumes awnless ..... HORDEUM

2' Spikelets 1 per node, stalked; inflorescence raceme-like

4. Lemma veins prominent, parallel; palea keeled, winged on lower 1/2 ..... PLEUROPOGON

4' Lemma veins converging at tip; palea not winged

5. Glumes >= florets, ± enclosing them ..... DANTHONIA (2)

5' Glumes ± = lower florets only

6. Spikelet axis thickened, falling with florets; lemma ± circular in ×-section ..... DESMAZERIA

6' Spikelet axis not thickened, not falling with florets; lemma flattened

7. Upper leaf sheaths closed; lemma tips generally 2-forked or 2-lobed ..... BROMUS

7' Upper leaf sheaths open; lemma tips obtuse or acute

8. Upper glume veins (3)5–9; palea keeled, ciliate ..... BRACHYPODIUM (2)

8' Upper glume veins 3(5); palea glabrous or hairy, but not keeled, nor ciliate ..... FESTUCA (2)

1' All spikelets sessile or nearly so (upper spikelets sometimes stalked in Scribneria)

9. Glume 1 (except in uppermost spikelets)

10. Stem internodes hollow; inflorescence axis remaining intact at maturity; spikelets breaking apart above glumes; lemma veins 5 ..... FESTUCA (2)

10' Stem internodes solid; inflorescence axis breaking apart at maturity, spikelets falling with axis segments; lemma veins 3 ..... HAINARDIA

9' Glumes 2

11. Spikelet bases ± embedded in cavities or pits in thickened inflorescence axis

12. Perennial herb from stolons or rhizomes; spikelets attached to one side of flattened inflorescence axis ..... STENOTAPHRUM

12' Annual; spikelets attached to both sides of rounded inflorescence axis

13. Spikelets awnless ..... PARAPHOLIS

13' Spikelets awned

14. Glumes awned; lemmas awnless; florets 2–5 ..... AEGILOPS

14' Glumes awnless; lemma awned; floret 1 ..... SCRIBNERIA

11' Spikelet bases not embedded in cavities or pits of thickened inflorescence axis

15. Spikelets borne on one side of inflorescence axis; lemma veins 3 ..... BOUTELOUA

15' Spikelets 2-ranked; lemma veins 5–9

16. Spikelets 2–8 per node ..... ELYMUS (2)

16' Spikelets 1 per node

17. Lemma keels ciliate ..... SECALE

17' Lemma keels (if present) not ciliate

18. Glumes > florets and generally enclosing them (except awns and lemma teeth) ..... DANTHONIA (2)

18' Glumes < florets

19. Fertile floret 1, subtended by 2 sterile florets ..... Ehrharta longiflora

19' Fertile florets 2+, sterile florets above the fertile ones

20. Auricles 0 ..... BRACHYPODIUM (2)

20a. Palea keels strongly ciliate; awns (when present) straight; nodes generally pubescent ..... BRACHYPODIUM

20a' Palea keels not ciliate; awns twisted, bent; nodes glabrous ..... [GAUDINIA]

20' Auricles present

21. Glumes and lemma backs rounded ..... ELYMUS (2)

21' Glumes and lemmas keeled

22. Perennial herb; lemma awns 1–6 mm ..... AGROPYRON

22' Annual; lemma awns to (0)4 cm ..... TRITICUM

Group 4: Inflorescence branches digitate, raceme-like, clustered, or in whorls; no further branching evident

1. Inflorescence branches digitate or clustered at tip of inflorescence axis

2. Glume and lemma awns 0

3. Perennial herb; floret 1; internal spikelet axis extended behind palea as a slender bristle, rarely bearing a sterile floret ..... CYNODON

3' Annual or short-lived perennial herb; florets 2+; internal spikelet axis not extended behind palea ..... ELEUSINE

2' Glumes and/or lemmas awned

4. Spikelets laterally compressed or cylindric, but not keeled; upper glume awn 0; tip of inflorescence branch not extending beyond last spikelet ..... CHLORIS (2)

4' Spikelets strongly keeled; upper glume awned; tip of inflorescence branch extending beyond last spikelet ..... DACTYLOCTENIUM

1' Inflorescence branches raceme-like, 1+ per node along a central, unbranched axis, or in whorls

5. Floret 1 per spikelet; plants of coastal marshes and wet places ..... SPARTINA

5' Florets 2+ per spikelet (except basal spikelet per branch in Bouteloua aristidoides); plants of various habitats

6. Fertile floret 1 per spikelet

7. Inflorescence branches 2+ per node ..... CHLORIS (2)

7' Inflorescence branches 1 per node

8. Spikelet laterally compressed; lowest floret bisexual ..... BOUTELOUA

8' Spikelet dorsally compressed; upper floret bisexual ..... ECHINOCHLOA

6' Fertile florets 2+ per spikelet

9. Lemma 3-veined, sometimes appearing 1-veined ..... LEPTOCHLOA

9' Lemma 5–several-veined

10. Upper glume 3-veined ..... FESTUCA

10' Upper glume 7-veined ..... SCLEROCHLOA

Group 5: Inflorescence panicle-like, open and spreading to compact, cylindrical or head-like; spikelets 1-flowered

1. Stem nodes purple-black; floret staminate ..... VENTENATA

1' Stem nodes green or straw-colored; floret bisexual

2. Glumes 0; palea 3-veined; plants of wet sites ..... LEERSIA

2' Glumes 1 or 2; palea, when present, 2-veined; plants generally of drier sites (except Oryza and some Phalaris)

3. Lower glume awns 2 ..... Muhlenbergia alopecuroides

3' Lower glume awn 0 or 1

4. Spikelets ± round, overlapping in 2 rows on 1 side of inflorescence branch; glumes winged, body transversely wrinkled ..... BECKMANNIA

4' Spikelets not round, nor overlapping in 2 rows; glumes not winged, body smooth or veined, but not transversely wrinkled

5. Glumes ciliate-keeled

6. Glumes united at base; lemma awned; palea 0 ..... ALOPECURUS

6' Glumes separate at base; lemma awnless; palea present ..... PHLEUM

5' Glumes glabrous to sparsely hairy, but not ciliate-keeled

7. Glumes unequal, tapering to a long point, ± swollen at base ..... GASTRIDIUM

7' Glumes equal or unequal, but not tapering to long points, not swollen at base

8. Glumes keeled, often winged; floret subtended by a membranous flap or tuft of hairs ..... PHALARIS

8' Glumes generally rounded, not winged; floret not subtended by a flap or tuft of hairs

9. Lemma generally hardened at maturity, margins generally overlapping and enclosing palea and grain; grain hardened, round in ×-section; callus well-developed, blunt or sharp-pointed

10. Stem internodes ± solid; lemma veins 3, awns generally straight; ligule of hairs or basal membrane long-ciliate ..... ARISTIDA

10' Stem internodes hollow; lemma veins 3–7, awns generally bent 1–2 ×; ligule generally membranous ..... STIPA

9' Lemma and grain membranous or firm, but not hardened, generally flattened; callus not especially well-developed

11. Spikelet axis extended beside or above floret as a glabrous or hairy stub or bristle

12. Spikelets breaking apart below glumes at maturity; stamens 1–2 ..... CINNA

12' Spikelets breaking apart above glumes at maturity; stamens 3

13. Annual; callus glabrous to sparsely hairy ..... APERA

13' Annual or perennial herb from stolons or rhizomes; callus hairy

14. Inflorescence dense, cylindrical; spikelets 12–14 mm; lemma awn 0 ..... AMMOPHILA

14' Inflorescence open, panicle-like; spikelets 2–4(11) mm; lemma awn 0.5–17 mm ..... CALAMAGROSTIS

11' Spikelet axis not extended beside or above floret

15. Plants of flooded fields and in adjacent ditches; stamens 6 ..... ORYZA

15' Plants terrestrial; stamens 1 or 3

16. Glumes with well-developed awns (except Polypogon viridis); spikelets breaking apart below glumes ..... POLYPOGON

16' Glumes acute, acuminate, or awn-tipped; spikelets breaking apart above glumes

17. Lemma vein 1, awn 0; leaf sheaths generally ciliate at tip; seed ejected from grain at maturity ..... SPOROBOLUS

17' Lemma vein 3 or 5, awn present or 0; leaf sheaths not ciliate at tip; seed remaining within grain at maturity

18. Lemma veins 5(3), faint; palea generally 0 or << lemma ..... AGROSTIS

18' Lemma veins 3, generally obvious; palea generally well-developed ..... MUHLENBERGIA

Group 6: Inflorescence panicle-like, open and spreading to compact, cylindrical or head-like; fertile florets 2+

1. One or both glumes >= lowest floret, sometimes enclosing all of them

2. Spikelet length ± = width; glumes, lemma papery to translucent, inflated, at right angles to spikelet axis ..... BRIZA

2' Spikelet longer than wide; glumes, lemma not papery to translucent, nor at right angles to axis

3. Glumes of 2 kinds, lower linear to lanceolate, upper 3–4× wider than lower when spread flat; spikelet axis breaking below glumes ..... SPHENOPHOLIS

3' Glumes similar in shape, equal in length or not; spikelets breaking above glumes and between florets (except Trisetum)

4. Lemma awnless

5. Spikelet axis extended beyond bisexual florets as a slender, hairy bristle, sometimes with a reduced floret at its tip

6. Spikelets shiny; glume keels minutely ciliate; axis internodes < 1 mm ..... KOELERIA (2)

6' Spikelets not shiny; glume keels not ciliate; axis internodes 1.5–2 mm ..... TRISETUM (3)

5' Spikelet axis not extended beyond bisexual florets

7. Perennial herb; palea veins swollen at base; spikelets 7–15 mm ..... [Danthonia decumbens]

7' Annual; palea veins not swollen at base; spikelets 4.5–7 mm ..... SCHISMUS

4' Lemma awned

8. Spikelets 15–50 mm ..... AVENA

8' Spikelets < 15(20) mm

9. Lemma awned at or below middle

10. Annual; lemma tip 2-lobed; spikelet axis not extended beyond upper floret ..... AIRA

10' Perennial herb (except Deschampsia danthonioides); lemma tip 2–4 toothed at truncate tip; spikelet axis generally extended beyond upper floret

11. Leaves generally basal, blades 1–3 mm wide; spikelet axis >= 0.75 mm beyond upper floret, generally densely hairy ..... DESCHAMPSIA

11' Leaves generally cauline, blades 3–7 mm wide; spikelet axis inconspicuous beyond upper floret, ± 0.5 mm, generally glabrous ..... VAHLODEA

9' Lemma awned at or near tip or between 2 teeth

12. Spikelet axis clearly hairy ..... TRISETUM (3)

12' Spikelet axis ± glabrous

13. Lemma hairy, hairs in 1+ transverse rows ..... RYTIDOSPERMA

13' Lemma glabrous or if hairy, hairs on margins or evenly distributed ..... DANTHONIA

1' Lower glume < lowest floret, never enclosing 2 or more florets

14. Lemma awnless

15. Lemma veins ± prominent, equally-spaced, parallel

16. Upper glume 1-veined; leaf sheath closed to near top ..... GLYCERIA

16' Upper glume 3-veined; leaf sheath open

17. Rhizomes 0; lemma faintly 5-veined; plants of saline or alkaline soils ..... PUCCINELLIA

17' Rhizomes present; lemma distinctly 7–9-veined; plants of freshwater sites ..... TORREYOCHLOA

15' Lemma veins not especially prominent, converging at tip

18. Leaf tips prow-shaped; callus and/or lemma base generally cobwebby-hairy ..... POA

18' Leaf tips flat; callus or lemma base glabrous to scabrous

19. Spikelet axis segments thickened, falling with florets; lemma ± round in ×-section ..... DESMAZERIA

19' Spikelet axis segments not thickened, not falling with florets; lemma flattened

20. Lower glume broadly translucent distally and along margins; uppermost florets vestigial, densely clustered, sometimes appearing as a club-shaped rudiment; leaf sheaths closed ..... MELICA (2)

20' Lower glume generally membranous or narrowly translucent near tip or margins only; uppermost florets, if vestigial, not densely clustered, club-shaped rudiment 0; leaf sheaths open or closed

21. Leaf sheath closed to near top; lemma tip 2-toothed; spikelets generally 15–70 mm ..... BROMUS (2)

21' Leaf sheath open for at least 1/2 its length; lemma tip tapering to a point; spikelets generally 3.5–12(18) mm ..... FESTUCA (2)

14' Lemma awned

22. Inflorescence often dense, cylindric, spike-like, or more open in full flower; spikelets shiny, palea colorless ..... KOELERIA (2)

22' Inflorescence branching evident; spikelets not especially shiny; palea brown or green, at least along veins

23. Spikelets in dense, 1-sided clumps on distal portions of panicle branches; lemma keels stiff-ciliate ..... DACTYLIS

23' Spikelets not densely clumped at ends of panicle branches; lemma keels not stiff-ciliate

24. Lower glume broadly translucent distally and along margins; uppermost florets vestigial, densely clustered, sometimes appearing as a club-shaped rudiment; leaf sheaths closed ..... MELICA (2)

24' Lower glume generally membranous or narrowly translucent near tip or margins only; uppermost florets, if vestigial, not densely clustered, club-shaped rudiment 0; leaf sheaths open or closed

25. Spikelet axis hairy, extended beyond upper florets; upper glume >= lowest floret ..... TRISETUM (3)

25' Spikelet axis generally glabrous, not extended beyond upper florets; upper glume < lowest floret

26. Leaf sheath closed; spikelet generally 1+ cm; lemma tip 2-toothed; ovary tip hairy ..... BROMUS (2)

26' Leaf sheath open for at least 1/2 its length (except in Festuca rubra); spikelet generally < 1 cm; lemma tip entire; ovary tip glabrous ..... FESTUCA (2)

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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