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Key to PoaceaeView taxon page for Poaceae
Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots. Key to Groups
1. Leaf blade  Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped. base constricted above sheath  A surrounding or partially surrounding, often tubular structure or part of a structure, such as a leaf base in Apiaceae or Poaceae. , forming false petiole  Leaf stalk, connecting leaf blade to stem; sometimes more or less indistinct. ; 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  Group of bracts more or less held together as a unit, subtending a flower, fruit (acorn cup), or inflorescence. ..... CENCHRUS 2' Spikelets not enclosed in bristly to spiny, bur-like involucre 3. Some or all florets  In Poaceae, a single flower and its immediately subtending bracts (lemma and generally palea, the lemma subtending the palea when the latter is present); in a sterile floret, the flower and sometimes palea are rudimentary or absent. modified into bulblets  1. Small bulb generally produced at the base of a bulb. 2. Any small, bulb-like structure that propagates a plant, often in a leaf or bract axil. 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  Both male and female reproductive parts occurring and functional in the same plant or structure (e.g., flower, spikelet, inflorescence). ; plants known only from sand dunes in Inyo Co. ..... SWALLENIA 4' Leaf blades generally soft, rounded to acute  Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle. , 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  Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise. solid; ligules 0 7' Spikelets spirally inserted on inflorescence axis 8. Plant glandular-sticky at maturity; inflorescence a dense, cylindric  Elongate, with parallel sides and, at any point, round in transverse section. spike  1. In flowering plants excluding Asteraceae, Cyperaceae, Poaceae, and some other groups, an unbranched inflorescence in which the flowers are sessile and nearly always open from the bottom to the top of the inflorescence. 2. In Asteraceae, Cyperaceae, Poaceae, and some other groups, a spike-like inflorescence is one in which the inflorescence units (e.g., heads in Asteraceae; spikelets in Cyperaceae and Poaceae), instead of individual flowers, are sessile and attached directly to the main axis of the inflorescence, not to branches, and in which floral development may or may not proceed as in 1. , generally fully exserted  Protruding out of surrounding structure(s) (e.g., stamens exserted from corolla). at maturity; spikelets  1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. dorsally compressed  Flattened side-to-side or front-to-back. ..... 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 panicle-like, open with evident branches; glumes not winged 11. Sheath open; glumes ± enclosing florets; lower lemma  In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. awns  1. Bristle-like appendage or elongation, generally terminal. 2. Stiff, needle-like pappus element in Asteraceae. 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  Completing life cycle (germination through death) in more than two years or growing seasons, generally non-woody (at least above ground) to woody; includes perennial herbs as well as subshrubs to trees; the abbreviation 'per' only refers to perennial herb, not to the word 'perennial' alone. 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  Pertaining to or within an axil, especially a leaf axil. , 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' Florets 2+; lemma >= 3-veined 15. Lemma awn 1. Bristle-like appendage or elongation, generally terminal. 2. Stiff, needle-like pappus element in Asteraceae. 0 17. Lemma 3-lobed, conspicuously ciliate  Having generally straight, conspicuous hairs along margins or edges. ; upper florets 3-awned ..... BLEPHARIDACHNE 17' Lemma 2-lobed or tapering to awn 13' Plants generally >> 15 cm; mature inflorescence clearly exceeding upper leaves 19. Spikelets 1–2 per inflorescence 19' Spikelets few to many in a well-developed inflorescence 21. Spikelets subtended by 1+ bristles, sterile branches, or long, silky hairs > spikelet 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. 22. Spikelets subtended by long, silky hairs from their bases, rachis  In ferns, primary axis of a compound or dissected frond blade. joints, or pedicels  Stalk of an individual flower in an inflorescence, or the corresponding structure in fruit. 23. Spikelets dissimilar, sessile  Without a petiole, peduncle, pedicel, or other kind of stalk. bisexual, stalked sterile ..... BOTHRIOCHLOA 22' Spikelets subtended by 1 or more generally stiff bristles or sterile branches 24' Bristles scabrous to long-ciliate 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  Longer than wide, with nearly parallel sides; wider than linear. , head-like; spikelets 1-flowered ..... LAGURUS 27' Inflorescence open, branching evident; spikelets 2-flowered 28' Spikelets single on ends of short capillary branches 29. Annual or short-live perennial herb without stolons or rhizomes; upper floret compressed side-to-side; naturalized, disturbed areas, slopes, NCoRO, SnJV, s CCo, SCoRO, SCo, WTR, PR ..... MELINIS 29' Perennial herb from stolons or rhizomes; upper floret compressed front-to-back; native, sandy soils, dunes, e SCo, D ..... Panicum urvilleanum 26' Glumes and lemma bodies glabrous to short-hairy 30. Glumes or lemma (perhaps only in a unisexual spikelet) with 3–9 awns or awn-like segments (lateral awns sometimes << than central 1) 31. Lemma awns 9, plumose  Plume-like, usually with the parts arrayed in three dimensions around an axis, or in tufts held together at the base; usually pertaining to small, finely divided structures, such as certain stigmas and pappus elements. ..... ENNEAPOGON 31' Lemma awns 0–3, not plumose 32. Lower glume  In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets. with (2)3–9 awns or awn-like segments 33' Spikelets 2–5 flowered 34. Annual; spikelets 1 per node  Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. ..... AEGILOPS 32' Lower glume awn 0 or 1 35' Spikelets 2–several-flowered 36' Inflorescence 1–many raceme-like or spike-like 1° branches; spikelets bisexual ..... BOUTELOUA 30' Glume or lemma awns 0–2 37. 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 37' 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 38. Plants bearing markedly dissimilar spikelets in the same or separate inflorescences 40' Aquatic annual 1–1.5 m; cultivated fields and adjacent ditches ..... [ZIZANIA]39' Spikelets bisexual or sterile 41. Inflorescence spike-like 42' Stem internodes hollow; central spikelet sessile, laterals stalked (except in Hordeum vulgare) ..... HORDEUM 41' Inflorescence panicle-like, open to dense 43' Lemma awned; spikelets paired or in pendant clusters 44. Inflorescence panicle-like with drooping clusters of 1 fertile spikelet and 1–3 sterile ones; spikelet clusters falling as 1 unit ..... LAMARCKIA 44' Inflorescence head-like or cylindric, spikelets generally paired; spikelets falling separately ..... CYNOSURUS 38' Plants bearing similar spikelets, differing only in size and degree of maturity 45' Spikelets attached to 1° or 2° branches (dissection may be needed to reveal branches) 46. Inflorescence a series of 2 or more digitate, raceme-like, clusters, or whorls of short-stalked 1° branches ..... Group 4 46' Inflorescence with 2° branches and/or with some spikelets attached directly to main axis 47' Spikelets 2–many-flowered (sterile florets reduced to small scales or hairy, awl-like rudiments) 48. Spikelets 2–8 per node, sessile, inflorescence generally a spike ..... ELYMUS 48' Spikelets 1 per node, generally stalked, inflorescence generally much-branched 49. Spikelets unisexual; plants dioecious 50. Leaf tips prow-shaped; lemma base with cottony or cobwebby tuft of hairs ..... POA 50' Leaf tips flat; lemma bases glabrous to scabrous 52. Fertile florets 2+ (occasionally 1 in Dissanthelium and Melica) 53' Lemma veins 3, generally prominent (laterals sometimes near margins) 54' Glumes < upper florets; florets 3–many 55' Lemma veins hairy, at least below 57. Spikelet breaking below glumes; lower floret bisexual, awn 0; upper floret staminate, awned ..... HOLCUS 57' Spikelet breaking above glumes; staminate or sterile floret(s) below fertile one (sometimes << fertile and easily overlooked) 58. Fertile floret generally awned 59. Perennial herb; nodes Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. green or straw-colored; spikelets breaking apart below lowest floret ..... ARRHENATHERUM (2) 59' Annual; nodes purple-black; spikelets breaking apart above lowest floret ..... VENTENATA 60' Lower staminate or sterile florets >= fertile one 61. Spikelets straw-colored or brown at maturity; stamens 2–3; auricles 0 (except in Anthoxanthum aristatum, A. odoratum) ..... ANTHOXANTHUM 61' 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 not branched above base (except inflorescence) 2. Leaves predominantly basal  At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary. 3. Stem internodes Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise. hollow; spikelets 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. unisexual (pls generally pistillate) ..... CORTADERIA 3' Stem internodes solid; spikelets bisexual Both male and female reproductive parts occurring and functional in the same plant or structure (e.g., flower, spikelet, inflorescence). ..... Stipa mauritanica 2' Leaves well distributed along stems 4. Inflorescence branches and spikelets glabrous 5. Glumes 0 or vestigial - inflorescence branches unisexual, spikelets remaining intact until harvested ..... [ZIZANIA]4' Inflorescence branches and/or spikelets hairy 7. Stem internodes solid; spikelets paired, one or both stalked 8. Spikelets unequally stalked; inflorescence axis remaining intact at maturity ..... IMPERATA 8' 1 spikelet 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. sessile Without a petiole, peduncle, pedicel, or other kind of stalk. , 2nd stalked; inflorescence axis breaking apart at maturity, segments with spikelets attached ..... SACCHARUM 7' Stem internodes hollow; spikelets 1 per node Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. 9. Spikelet axis glabrous; lemma In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. densely hairy ..... ARUNDO 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 Without a petiole, peduncle, pedicel, or other kind of stalk. spikelets), ± equal, 1 or both generally > upper floret (except awns); fertile and sterile lemmas In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. generally translucent 2. Spikelets 1 per node Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. , subtended by a hairy bristle ..... ANDROPOGON 2' Spikelets 2 or 3 per node, 1 sessile and 1 (2) stalked 3. Terminal spikelets 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. per branch in 3s, 1 sessile and 2 stalked ..... SORGHUM 3' Terminal spikelets per branch in 2s, 1 sessile and 1 stalked 4' Inflorescence branched, panicle-like 5. Inflorescence internodes Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise. and spikelet 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. stalks with a translucent longitudinal groove; lowest pair of spikelets per raceme  In flowering plants excluding Asteraceae, Cyperaceae, Poaceae, and some other groups, an unbranched inflorescence in which the flowers are borne on pedicels and nearly always open from the bottom to the top of the inflorescence. 2. In Asteraceae, Cyperaceae, Poaceae, and some other groups, a raceme-like inflorescence is one in which the inflorescence units (e.g., heads in Asteraceae; spikelets in Cyperaceae and Poaceae), instead of individual flowers, are stalked and attached directly to the main axis of the inflorescence, not to branches, and in which floral development may or may not proceed as in 1. 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 In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets. generally < upper (0), upper glume <= upper floret; sterile lemma In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. membranous and resembling upper glume, fertile lemma leathery to hardened (membranous in Digitaria) 6. Inflorescence spike-like; spikelet bases ± embedded in 1 side of flattened, thickened axis ..... STENOTAPHRUM 6' Inflorescence panicle-like or a series of paired, digitate, or racemose branches; spikelets not embedded, on 1 or more sides of rounded, unthickened axes 7' Spikelet not subtended by cup- or ring-like structure 9. Inflorescence a series of digitate or raceme-like branches 9' Inflorescence panicle-like
Group 3: Inflorescence solitary, spike-like or raceme-like; spikelets sessile or stalked
1. Some or all spikelets 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. stalked 2. Spikelets 3 per node Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. , sessile Without a petiole, peduncle, pedicel, or other kind of stalk. and stalked (or only stalk remaining after upper spikelet 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. has fallen); inflorescence spike-like 3. Stem internodes Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise. 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  1. In Asteraceae, a scale-like bract that subtends an individual flower on the receptacle (equal to 'chaff scale' in TJM), absent in some genera, restricted to a ring separating ray and disk flowers in most tarweed species. 2. In Poaceae, the distal, generally smaller of two sheathing bracts subtending a flower, generally two-veined and -keeled and ensheathed by the lemma; with the lemma and flower, comprising the floret. keeled, winged on lower 1/2 ..... PLEUROPOGON 4' Lemma veins converging at tip; palea not winged 5. Glumes >= florets In Poaceae, a single flower and its immediately subtending bracts (lemma and generally palea, the lemma subtending the palea when the latter is present); in a sterile floret, the flower and sometimes palea are rudimentary or absent. , ± enclosing them ..... DANTHONIA (2) 5' Glumes ± = lower florets only 6. Spikelet axis thickened, falling with florets; lemma In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. ± circular in ×-section ..... DESMAZERIA 6' Spikelet axis not thickened, not falling with florets; lemma flattened 7. Upper leaf  Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets). sheaths closed; lemma tips generally 2-forked or 2-lobed ..... BROMUS 7' Upper leaf sheaths open; lemma tips obtuse  Having a short-tapered, blunt tip or base, the sides convex or straight and converging at more than a right angle. or acute Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle. 8. Upper glume In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets. veins (3)5–9; palea keeled, ciliate Having generally straight, conspicuous hairs along margins or edges. ..... 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; 0 in Elymus californicus) 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 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 14. Glumes awned; lemmas In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. awnless; florets 2–5 ..... AEGILOPS 11' Spikelet bases not embedded in cavities or pits of thickened inflorescence axis 15' Spikelets 2-ranked; lemma veins 5–9 17' Lemma keels (if present) not ciliate 18. Glumes > florets and generally enclosing them (except awns 1. Bristle-like appendage or elongation, generally terminal. 2. Stiff, needle-like pappus element in Asteraceae. and lemma teeth) ..... DANTHONIA (2) 19' Fertile florets 2+, sterile florets above the fertile ones 21. Palea keels strongly ciliate; awns (when present) straight; nodes Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. generally pubescent ..... BRACHYPODIUM (2) 21' Palea keels not ciliate; awns twisted, bent; nodes glabrous ..... [GAUDINIA]22' Glumes and lemmas keeled
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 In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. awns 1. Bristle-like appendage or elongation, generally terminal. 2. Stiff, needle-like pappus element in Asteraceae. 0 3. Perennial herb; floret 1; internal spikelet 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. axis extended behind palea 1. In Asteraceae, a scale-like bract that subtends an individual flower on the receptacle (equal to 'chaff scale' in TJM), absent in some genera, restricted to a ring separating ray and disk flowers in most tarweed species. 2. In Poaceae, the distal, generally smaller of two sheathing bracts subtending a flower, generally two-veined and -keeled and ensheathed by the lemma; with the lemma and flower, comprising the floret. as a slender bristle, rarely bearing a sterile floret ..... CYNODON 3' Annual or short-lived perennial Completing life cycle (germination through death) in more than two years or growing seasons, generally non-woody (at least above ground) to woody; includes perennial herbs as well as subshrubs to trees; the abbreviation 'per' only refers to perennial herb, not to the word 'perennial' alone. herb; florets In Poaceae, a single flower and its immediately subtending bracts (lemma and generally palea, the lemma subtending the palea when the latter is present); in a sterile floret, the flower and sometimes palea are rudimentary or absent. 2+; internal spikelet axis not extended behind palea ..... ELEUSINE 2' Glumes and/or lemmas In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. awned 4. Spikelets laterally compressed Flattened side-to-side or front-to-back. or cylindric Elongate, with parallel sides and, at any point, round in transverse section. , but not keeled; upper glume In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets. awn 1. Bristle-like appendage or elongation, generally terminal. 2. Stiff, needle-like pappus element in Asteraceae. 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 Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. 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 At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary. spikelet per branch in Bouteloua aristidoides); plants of various habitats 6. Fertile floret 1 per spikelet 7' Inflorescence branches 1 per node 8. Spikelet laterally compressed; lowest floret bisexual Both male and female reproductive parts occurring and functional in the same plant or structure (e.g., flower, spikelet, inflorescence). ..... BOUTELOUA 6' Fertile florets 2+ per spikelet 9' Lemma 5–several-veined
Group 5: Inflorescence panicle-like, open and spreading to compact, cylindrical or head-like; spikelets 1-flowered
1. Stem nodes Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. purple-black; floret staminate ..... VENTENATA 1' Stem nodes green or straw-colored; floret bisexual Both male and female reproductive parts occurring and functional in the same plant or structure (e.g., flower, spikelet, inflorescence). 2. Glumes 0; palea 1. In Asteraceae, a scale-like bract that subtends an individual flower on the receptacle (equal to 'chaff scale' in TJM), absent in some genera, restricted to a ring separating ray and disk flowers in most tarweed species. 2. In Poaceae, the distal, generally smaller of two sheathing bracts subtending a flower, generally two-veined and -keeled and ensheathed by the lemma; with the lemma and flower, comprising the floret. 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 In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets. awns 1. Bristle-like appendage or elongation, generally terminal. 2. Stiff, needle-like pappus element in Asteraceae. 2 ..... Muhlenbergia alopecuroides 3' Lower glume awn 1. Bristle-like appendage or elongation, generally terminal. 2. Stiff, needle-like pappus element in Asteraceae. 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 6. Glumes united at base; lemma In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. awned; palea 0 ..... ALOPECURUS 5' Glumes glabrous to sparsely hairy, but not ciliate-keeled 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 Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise. ± solid; lemma veins 3, awns generally straight; ligule  1. In Asteraceae, the 5-lobed, strap- or fan-shaped outer portion of the corolla of a ligulate flower. 2. In most Poaceae and some other grass-like plants, an appendage at the adaxial junction of leaf sheath and blade, generally membranous, sometimes formed of hairs. 3. In Isoetes and, more obscurely, in Selaginella, a membrane that wholly or partially covers a sporangium. of hairs or basal At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary. 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 or perennial Completing life cycle (germination through death) in more than two years or growing seasons, generally non-woody (at least above ground) to woody; includes perennial herbs as well as subshrubs to trees; the abbreviation 'per' only refers to perennial herb, not to the word 'perennial' alone. herb from stolons or rhizomes; callus hairy 14. Inflorescence dense, cylindrical; spikelets 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. 12–14 mm; lemma awn 0 ..... AMMOPHILA 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 Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle. , acuminate  Having a long-tapered, sharp tip, the sides concave. , or awn-tipped; spikelets breaking apart above glumes 17. Lemma vein 1, awn 0; leaf Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets). sheaths generally ciliate Having generally straight, conspicuous hairs along margins or edges. 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
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 In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. papery to translucent, inflated, at right angles to spikelet 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. 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  Elongate, with nearly parallel sides; narrower than elliptic or oblong. to lanceolate  Narrowly elongate, widest in the basal half, often tapered to an acute tip. , 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 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. breaking above glumes and between florets In Poaceae, a single flower and its immediately subtending bracts (lemma and generally palea, the lemma subtending the palea when the latter is present); in a sterile floret, the flower and sometimes palea are rudimentary or absent. (except Trisetum) 5. Spikelet axis extended beyond bisexual Both male and female reproductive parts occurring and functional in the same plant or structure (e.g., flower, spikelet, inflorescence). florets as a slender, hairy bristle, sometimes with a reduced floret at its tip 6. Spikelets shiny; glume In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets. keels minutely ciliate Having generally straight, conspicuous hairs along margins or edges. ; axis internodes Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise. < 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 1. In Asteraceae, a scale-like bract that subtends an individual flower on the receptacle (equal to 'chaff scale' in TJM), absent in some genera, restricted to a ring separating ray and disk flowers in most tarweed species. 2. In Poaceae, the distal, generally smaller of two sheathing bracts subtending a flower, generally two-veined and -keeled and ensheathed by the lemma; with the lemma and flower, comprising the floret. veins swollen at base; spikelets 7–15 mm ..... [Danthonia decumbens] 4' Lemma awned (sometimes awnless in Avena sativa) 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  Abruptly (not gradually) narrower or smaller at base or tip, as if cut straight across or nearly so. tip; spikelet axis generally extended beyond upper floret 11. Leaves generally basal At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary. , 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 ± glabrous 1' Lower glume < lowest floret, never enclosing 2 or more florets 15. Lemma veins ± prominent, equally-spaced, parallel, wet places 16. Upper glume 1-veined; leaf Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets). sheath A surrounding or partially surrounding, often tubular structure or part of a structure, such as a leaf base in Apiaceae or Poaceae. closed to near top ..... GLYCERIA 16' Upper glume 3-veined; leaf sheath open 15' Lemma veins not especially prominent, generally converging at tip, wet or dry places 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) 22. Inflorescence often dense, cylindric Elongate, with parallel sides and, at any point, round in transverse section. , 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  1. In flowering plants excluding Asteraceae, Cyperaceae, Poaceae, and some other groups, a branched inflorescence in which the basal or lateral flowers (or some of them) open before the terminal or central flowers on any axis. 2. In Asteraceae, Cyperaceae, Poaceae, and some other groups, a panicle-like inflorescence is one in which at least some of the inflorescence units (e.g., heads in Asteraceae; spikelets in Cyperaceae and Poaceae), instead of individual flowers, are attached (stalked or unstalked) to branches and not directly to the main axis of the inflorescence and in which floral development may or may not proceed as in 1. 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  Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.). , occasionally minutely 2-toothed; ovary tip glabrous or hairy ..... FESTUCA (2)
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