Poaceae
Poaceae tribe Poeae
grass family
annual or perennial, herbaceous or woody, usually erect or ascending, sometimes prostrate or decumbent for much of their length, occasionally climbing, rarely floating;
nodes prominent, sometimes concealed by the leaf sheaths;
internodes hollow or solid, bases meristematic; branching from the basal nodes only or from the basal, middle, and upper nodes;
basal branching extravaginal or intravaginal; branching from the upper nodes intravaginal, extravaginal, or infravaginal.
annual, not woody, not branching above the base;
internodes usually hollow.
usually open for most of their length, sometimes closed;
collars without tufts of hair on the sides;
auricles usually absent;
ligules membranous to hyaline, sometimes ciliate, those of the upper and lower cauline leaves usually similar;
pseudopetioles not developed;
blades linear to narrowly lanceolate, venation parallel, cross venation not evident, without arm or fusoid cells, epidermes without microhairs, not papillate, cross sections non-Kranz.
alternate, 2-ranked, each composed of a sheath and blade encircling the culm or branch;
sheaths usually open, sometimes closed, the margins fused for all or part of their length;
auricles (lobes of tissue extending beyond the margins of the sheaths on either side) sometimes present;
ligules usually present at the sheath-blade junction, particularly on the adaxial surface, abaxial ligules common in the Bambusoideae, membranous, sometimes ciliate, adaxial ligules usually present, of membranous to hyaline tissue, a line of hairs, or a ciliate membrane;
blades usually linear to lanceolate, occasionally ovate to triangular, bases sometimes pseudopetiolate (having a petiole-like constriction), venation usually parallel, sometimes with evident cross veins, occasionally divergent.
(synflorescences) usually compound, composed of simple or complex aggregations of primary inflorescences, aggregations paniculate, spicate, or racemose or of spikelike branches, often with an evident rachis (central axis), primary inflorescences spikelets, pseudospikelets, or spikelet equivalents;
inflorescence branches usually without obvious bracts.
terminal, usually panicles, sometimes spikes, panicles sometimes spikelike or reduced to racemes in depauperate specimens;
disarticulation usually above the glumes and beneath the florets, sometimes below the glumes.
with (0-1)2(3-6) glumes (empty bracts) subtending 1-60 florets, glumes and florets distichously attached to a rachilla (central axis);
pseudospikelets with bud-subtending bracts below the glumes.
0.7-50 mm, laterally compressed, sometimes weakly so, sometimes viviparous, usually with 2-22 florets, sometimes with 1, sterile florets usually distal to the reproductively functional florets, sometimes with 1 or 2 staminate or sterile florets below a bisexual floret, sterile florets often reduced in size;
rachillas sometimes prolonged beyond the base of the distal florets.
usually with an odd number of veins, sometimes awned.
(0,1)2, equal or unequal, shorter or longer than the adjacent florets, sometimes exceeding the distal florets;
florets laterally compressed;
calluses glabrous or hairy, not well developed;
lemmas lanceolate to ovate, 1-7(9)-veined, unawned or awned, veins usually converging distally, sometimes parallel, awns from basal to terminal on the lemmas, straight or bent;
paleas 2-keeled, from shorter than to longer than the lemmas, sometimes absent or minute;
lodicules 2, membranous, not or weakly veined;
anthers 3;
ovaries usually glabrous, sometimes hairy distally;
styles 2, bases free.
longitudinally grooved or not, not beaked, pericarp thin;
hila punctate to linear;
embryos from 1/4-1/3 as long as the caryopses.
bisexual, staminate, or pistillate, usually composed of a lemma (lower bract) and palea (upper bract), lodicules, and reproductive organs, often laterally or dorsally compressed, sometimes round in cross section;
lemmas usually with an odd number of veins, often awned, bases frequently thick and hard, forming a callus, backs rounded or keeled over the midvein, awns usually 1(-3), arising basally to terminally;
paleas usually with 2 major veins, with 0 to many additional veins between the major veins, sometimes also in the margins, often keeled over the major veins;
lodicules (0)2-3, inconspicuous, usually without veins, bases swelling at anthesis;
stamens usually 3, sometimes 1(2) or 6+, filaments capillary, anthers versatile, usually all alike within a floret, sometimes 1 or 2 evidently longer than the others;
ovaries 1-loculed, with (1)2-3(4) styles or style branches, stigmatic region usually plumose.
caryopses, pericarp usually dry and adhering to the seed, sometimes fleshy or dry and separating from the seed at maturity or when moistened;
embryos ⅕ as long as to almost equaling the caryopses, highly differentiated with a scutellum (absorptive organ), a shoot with leaf primordium covered by the coleoptile (shoot sheath), and a root covered by the coleorhiza (root sheath);
hila punctate to linear.
= 5,6, 7, 9, 10, 11, 12.
= 7.
Poaceae
Poaceae tribe Poeae
The Poaceae or grass family includes approximately 700 genera and 11,000 species (Chen et al. 2006). The two grass volumes in this series treat 10 subfamilies, 25 tribes, 236 genera, and 1373 species. Of these, all the subfamilies, 22 tribes, 136 genera, and 892 species are native to the Flora region; 2 tribes, 78 genera, and 290 species have become established in the region. The remaining taxa include ornamental species; species grown for research purposes; species that, if introduced to the region, would pose a threat to important agricultural species; and a few waifs, i.e., species that have been found in the region but have not become established. Most of the waifs are species that were found on ballast dumps near ports around the turn of the last century.
Grasses constitute the fourth largest plant family in terms of number of species. Nevertheless, the family is clearly more significant than any other plant family in terms of geographic, ecological, and economic importance. Grasses grow in almost all terrestrial environments, including dense forests, open deserts, and freshwater streams and lakes. There are no truly marine grasses, but some species grow within reach of the highest tides.
In addition to being widely distributed, grasses are often dominant or co-dominant over large areas. The importance of such areas to humans is reflected in the many words that exist for grasslands, words such as meadow, palouse, pampas, prairie, savanna(h), steppe, and veldt. Not surprisingly, given their abundance and prevalence, grasses are of great ecological importance as soil stabilizers and as providers of shelter and food for many different animals.
The economic importance of grasses to humans is almost impossible to overestimate. The wealth of individuals and countries is dependent on the availability of such sources of grain as Triticum (wheat), Oryza (rice), Zea (corn or maize), Hordeum (barley), Avena (oats), Secale (rye), Eragrostis (tef), and Zizania (wild rice). Most countries invest heavily in research programs designed to develop better strains of these grasses and the many other grasses that are used for livestock, soil stabilization, and revegetation. Developing improved grasses for recreation areas, such as playing fields, golf courses, and parks, is also a major industry in many parts of the world; increasing recognition of the aesthetic value af grasses is reflected in their prominence in horticultural catalogs.
There are, of course, grasses that are considered undesirable, at least in some parts of the world, but even the most obnoxious grasses may be well-regarded over a portion of their range. For instance, Bromus tectorum (cheatgrass) is a noxious, fire-prone invader of western North American ecosystems; it is also welcomed as a source of early spring feed in some parts of the Flora region. Cynodon dactylon (bermudagrass) is listed as a noxious weed in some jurisdictions; in others it is valued as a lawn grass.
Although grasses are widespread and often dominant in open areas, all evidence points to an origin of the family in forests, most likely in the Southern Hemisphere, at least 55-70 mya (Grass Phylogeny Working Group 2001). Recent evidence from phytoliths (isolated silica bodies commonly produced inside the epidermal cells of grasses and some other plants) embedded in fossil coprolites strongly suggests that grasses evolved earlier in the Cretaceous than previously thought (Prasad et al. 2005). Living representatives of the three earliest lineages of the grass family, together comprising about 30 species, are perennial, broad-leaved plants of relatively small stature, native to tropical or subtropical forests in South America, Africa, southeast Asia, some Pacific Islands, and northern Australia. The major diversification of the family probably occurred in the mid-Cenozoic, and was associated with climatic changes that produced more open habitats. All major lineages of the grass family were present by the middle of the Miocene (Jacobs et al. 1999), and C4 photosynthesis in grasses had evolved by then, as well.
Molecular and morphological data unequivocally support a single origin for the Poaceae (Grass Phylogeny Working Group 2001). The caryopsis, a single-seeded, usually dry and indehiscent fruit with the pericarp usually strongly adherent to the seed, and the laterally positioned, highly differentiated embryo are unique to grasses. Beyond the three early-diverging lineages (Anomochlooideae Potztal, Pharoideae, and Puelioideae L.G. Clark et al.), the great diversity of grasses can be divided into two major lineages: the BEP clade (Bambusoideae, Ehrhartoideae, and Pooideae); and the PACMCAD clade (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae Pilger, Centothecoideae, Aristidoideae, and Danthonioideae, i.e., the PACCAD clade of volume 25 plus the Micrairoideae, support for recognition of which was obtained after publication of that volume). Relationships among the BEP grass lineages remain uncertain, and some evidence points to the Pooideae as being more closely related to the PACMCAD clade than to the Bambusoideae or Ehrhartoideae. The PACMCAD clade includes all known C4 or warm-season grasses.
The closest relatives of the Poaceae lie within a group of six families, all native primarily to the Southern Hemisphere: Joinvilleaceae Toml. & A.C. Sm., Ecdeiocoleaceae D.F. Cutler &c& Airy Shaw, Restionaceae R. Br., Centrolepidaceae Endl., Anarthriaceae D.E Cutler &c& Airy Shaw, and Flagellariaceae Dumort. (Poales Small, sensu stricto). Joinvilleaceae, Ecdeiocoleaceae, and Poaceae constitute a three family clade, with Ecdeiocoleaceae probably being closer than Joinvilleaceae to the Poaceae (Bremer 2000; Bremer 2002; Michelangeli et al. 2003). Rudall et al. (2005), based on a study of reproductive structures in the Ecdeiocoleaceae, suggest that the grass caryopsis may represent "one end of a transformation series embodied by the reduced gynoecial structure and indehiscent fruit of other Poales such as Flagellaria and Ecdeiocolea" (p. 1441).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The Poeae constitute the largest tribe of grasses, encompassing around 115 genera and 2500 species. The species are primarily cool-temperate to arctic in their distribution. In the Flora region, there are 63 non-hybrid genera with 344 species, and 4 hybrid genera, each of which has one species. Many of the tribe's species are well known as lawn and pasture grasses, for example, Poa pratensis (Kentucky bluegrass), Dactylis glomerata (orchard grass), and Phleum pratense (timothy).
The tribe's circumscription and its infratribal taxonomy are unclear. It is interpreted here as including generic groups that are, or have been, treated in other works as tribes (e.g., Agrostideae Dumort., Aveneae Dumort., Hainardeae Greut., and Phalarideae Dumort.). Some of these are sometimes recognized as subtribes, often with modified circumscriptions. Recent studies (e.g., Catalan et al. 1997, 2004; Soreng and Davis 1998) indicate that there are some infratribal groupings that, based on chloroplast DNA data, appear stable; other groupings do not. In addition, there is little support for the monophyly of some genera, notably Festuca and its allies.
The following key does not include these four hybrid genera: xAgropogon (Agrostis x Polypogon, p. 668), xArctodupontia (Arctopbila x Dupontia, p. 604), xDupoa (Dupontia x Poa, p. 601), and ×Pucciphippsia (Puccinellia x Phippsia, p. 477). They are described on the pages indicated. In the key that follows, branch measurements include spikelets, but not awns.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key to Tribes
1. Leaf blades with divergent veins; spikelets unisexual and dimorphic, the pistillate lemmas with uncinate hairs (Pharoideae; FNA 24:11) | Phareae |
1. Leaf blades with parallel veins; spikelets bisexual, unisexual, or modified into plantlets, the pistillate lemmas never with uncinate hairs. | → 2 |
2. Culms perennial, woody or herbaceous, often developing complex branching systems from the upper nodes; leaves on the upper portion of the culms, or distal on the branches, usually pseudopetiolate (Bambusoideae). | → 3 |
3. Culms woody, to 30 m tall; leaves strongly dimorphic, those of the main culms (culm leaves) with expanded sheaths and often with reduced, non-photosynthetic blades, those of the branches (foliage leaves) with abaxial ligules; blades of the distal leaves not folding at night or under stress; florets bisexual; plants native or introduced, often cultivated (FNA 24:15) | Bambuseae |
3. Culms herbaceous, to 3.5 m tall or climbing; leaves not strongly dimorphic; blades of the distal leaves often folding at night or under stress; florets unisexual; plants known only in cultivation in the Flora region (FNA 24:29) | Olyreae |
2. Culms usually annual, sometimes facultatively perennial, rarely woody, sometimes branching from the upper nodes but the branching system not complex; leaves usually not pseudopetiolate. | → 4 |
4. Spikelets almost always with 2 florets, the lower florets in the spikelets always sterile or staminate, frequently reduced to lemmas, occasionally missing, the upper florets bisexual, staminate, or sterile, unawned or awned from the lemma apices or, if the lemmas bilobed, from the sinuses; glumes membranous and the upper lemma stiffer than the lower lemma, or both florets reduced and concealed by the stiff to coriaceous glumes; rachilla not prolonged beyond the second floret (Panicoideae, in part). | → 5 |
5. Glumes flexible, membranous, the lower glumes usually shorter than the upper glumes, sometimes missing, the upper glumes usually subequal to or exceeded by the upper floret; lower lemmas membranous; upper lemmas usually coriaceous to indurate, sometimes membranous; upper paleas similar in texture; spikelets usually single or in pairs, occasionally in triplets and all pedicellate, often shortly so) (FNA 25:353) | Paniceae |
5. Glumes stiff, coriaceous to indurate, often subequal, at least 1 and usually both exceeding the upper floret (excluding the awn); both lemmas hyaline; paleas hyaline or absent; most spikelets in pairs or triplets, at least 1 spikelet in each group usually sessile; pedicels shorter or only a little longer than the sessile spikelets (FNA 25:602) | Andropogoneae |
4. Spikelets either with other than 2 florets or, if with 2, the lower floret bisexual or the upper floret awned from the back or base of the lemma, or the spikelets bulbiferous; glumes usually membranous; lemmas scarious to indurate; rachilla sometimes prolonged beyond the distal floret. | → 6 |
6. Spikelets with 1 floret; lemmas terminating in a 3-branched awn (the lateral branches sometimes greatly reduced); callus well developed; ligules usually of hairs, sometimes ciliate membranes, the cilia longer than the membranous base (Aristidoideae; FNA 25:314) | Aristideae |
6. Spikelets with more than 1 floret or, if only 1, the lemma not terminating in a 3-branched awn; callus development various; ligules various. | → 7 |
7. Spikelets with 1 sexual floret or the spikelets bulbiferous; glumes absent or less than ¼ as long as the adjacent floret; lower glumes, if present, without veins, upper glumes, if present, veinless or 1-veined. | → 8 |
8. Upper glumes present, 1-veined; lower glumes absent or much shorter than the upper glumes and lacking veins (Pooideae, in part; FNA 24:57) | Brachyelytreae |
8. Both glumes absent or lacking veins. | → 9 |
9. Inflorescences 1-sided spikes; triangular in cross section, [Pooideae, in part; FNA 24:62) | Nardeae |
9. Inflorescences panicles; spikelets laterally compressed or terete. | → 10 |
10. Culms aerenchymatous, 20-500 cm long; plants of wet places, often emergent, sometimes floating; lemmas of the bisexual or pistillate florets 3-14-veined; paleas 3-10-veined (Ehrhartoideae, in part; FNA 24:36) | Oryzeae |
10. Culms not aerenchymatous, 2-300 cm tall; plants of wet or dry habitats but not emergent or floating; lemmas of the bisexual or pistillate florets 1-3-veined; paleas 2-veined. | → 11 |
11. Culms 2-19 cm tall; plants of cold or damp habitats, not rhizomatous; sheaths of the flag leaves closed for at least 1/2 their length; caryopses exposed at maturity (Pooideae, in part; FNA 24:378) | Poeae |
11. Culms 5-300 cm tall; plants usually of warm or dry habitats, often rhizomatous; sheaths of the flag leaves open to the base; caryopses not exposed at maturity (Chloridoideae, in part; FNA 25:14) | Cynodonteae |
7. Spikelets usually with more than 1 sexual floret; usually with 2 glumes, 1 or both glumes often longer than ¼ the length of the adjacent floret and/or with more than 1 vein, always longer in taxa with 1 sexual floret. | → 12 |
12. Lemmas unawned, flabellate or with (5)7-15 awnlike teeth (Chloridoideae, in part). | → 13 |
13. Plants not viscid, usually perennial; ligules present, composed of hairs (FNA 25:285) | Pappophoreae |
13. Plants viscid annuals; ligules absent (FNA 25:290) | Orcuttieae |
12. Lemmas awned or unawned, lanceolate, rectangular, or ovate, apices entire, mucronate, bilobed, or bifid, occasionally 4-lobed or 4-5-toothed, sometimes erose. | → 14 |
14. Cauline leaf sheaths closed for 1/2 their length or more; glumes usually exceeded by the distal florets, sometimes greatly so (Pooideae, in part). | → 15 |
15. Spikelets 5-80 mm long, not bulbiferous; lemmas usually awned, often bilobed or bifid, veins convergent distally; ovary apices hairy (FNA 24:193) | Bromeae |
15. Spikelets 0.7-60 mm long, sometimes bulbiferous; lemmas often unawned, not both bilobed/bifid and with convergent veins; ovary apices usually glabrous. | → 16 |
16. Lemma veins (4)5-15, usually prominent, parallel distally; spikelets 2.5-60 mm long, not bulbiferous (FNA 24:67) | Meliceae |
16. Lemmas veins 1-9, often inconspicuous, usually convergent distally; spikelets 0.7-18(20) mm long, sometimes bulbiferous (FNA 24:378) | Poeae |
14. Cauline leaf sheaths open for at least 1/2 their length; glumes exceeding or exceeded by the distal florets. | → 17 |
17. Spikelets with 1 floret; lemmas terminally or subterminally awned, the junction of the awn and lemma conspicuous; rachillas not prolonged beyond the base of the floret (Pooideae, in part; FNA 24:109) | Stipeae |
17. Spikelets with 1-60 florets; lemmas unawned or awned, awns basal to terminal, if terminal or subterminal, the lemma-awn junction not conspicuous; rachillas often prolonged beyond the base of the distal floret. | → 18 |
18. Ligules, at least of the flag leaves, of hairs, a ciliate ridge or membrane bearing cilia longer than the basal ridge or membrane; leaves usually hairy on either side of the ligule; auricles absent. | → 19 |
19. Lemmas of the fertile florets with 3-11 inconspicuous veins, never glabrous, if with 3 veins, pilose throughout or with transverse rows of tufts of hair, if with 5-11 veins, the margins pilose proximally, the hairs not papillose-based; lemma apices usually bilobed or bifid and awned or mucronate from the sinus, if acute to acuminate, the lemmas pilose; awns twisted proximally (Danthonioideae; FNA 25:298) | Danthonieae |
19. Lemmas of the fertile florets usually with 1-3 conspicuous veins, sometimes with 3 inconspicuous veins or 5-11 veins, often glabrous, if with 3 veins, usually glabrous throughout or hairy over the veins, sometimes the margins with papillose-based hairs; lemma apices acute to obtuse, bilobed, or 4-lobed, often mucronate or awned from the sinuses; awns usually not twisted. | → 20 |
20. Lemmas 1-11-veined, veins glabrous or hairy, margins without papillose-based hairs; rachillas and calluses not pilose, sometimes strigose or strigulose; basal internodes of the culms not persistent, not swollen and clavate (Chloridoideae, in part; FNA 25:14) | Cynodonteae |
20. Lemmas 3(5)-veined, veins glabrous, margins sometimes with papillose-based hairs; rachillas or calluses pilose or the basal internodes of the culms persistent, often swollen and clavate (Arundinoideae, in part; FNA 25:7) | Arundineae |
18. Ligules membranous, if ciliate, the cilia shorter than the membranous base; leaves usually glabrous on either side of the ligule; auricles present or absent. | → 21 |
21. Inflorescences panicles or unilateral racemes, not spikelike, without spike-like branches; spikelets solitary, the lowest 0-4 florets in a spikelet sterile or staminate, the distal florets sexual. | → 22 |
22. Spikelets with (1)2-25 bisexual florets; all lemmas similar in size and shape; glumes and lemmas membranous (Centothecoideae). | → 23 |
23. Culms 35-150 cm tall; spikelets with (2)3-26 florets, including the lowest (0)1-4 sterile or staminate florets; lower glumes (1)2-9-veined (FNA 25:344) | Centotheceae |
23. Culms 150-400 cm tall; spikelets with 2-4 florets, including the lowest sterile floret; glumes 0-1-veined (FNA 25:349) | Thysanolaeneae |
22. Spikelets with 1 bisexual or unisexual floret; lemmas of the sterile florets usually differing in size and shape from those of the sexual floret; glumes membranous, lemmas of the sexual florets firmer. | → 24 |
24. Lemmas of the lower florets coriaceous, at least the upper exceeding the sexual floret (Ehrhartoideae, in part; FNA 24:33) | Ehrharteae |
24. Lemmas of the lower florets membranous, often both much shorter than the sexual floret, sometimes subequal to it, sometimes only 1 sterile floret present (Pooideae, in part; FNA 24:378) | Poeae |
21. Inflorescences panicles, racemes, or spikes; spikelets sometimes in pairs or triplets, sterile florets, if any, distal to the bisexual or pistillate florets. | → 25 |
25. Lemmas with 1-3 or 9-11 conspicuous veins; sheaths open; blade cross sections with Kranz leaf anatomy (Chloridoideae, in part; FNA 25:14) | Cynodonteae |
25. Lemmas with (1)3-15 often inconspicuous veins, if with 3 conspicuous veins, the sheaths closed; sheaths open or closed; blade cross sections without Kranz leaf anatomy. | → 26 |
26. Inflorescences spikes or spikelike; spikelets 1-5+ per node, at least 1 spikelet sessile or subsessile (Pooideae, in part). | → 27 |
27. Upper glumes 5-9-veined; spikelets subsessile and solitary at the nodes; auricles absent (FNA 24:187) | Brachypodieae |
27. Upper glumes 1-5-veined; spikelets 1-5+ per node, usually at least 1 sessile at each node, sometimes highly reduced branches present; auricles present or absent. | → 28 |
28. Inflorescences with 1-5 spikelets at a node, if 3, usually with 1 sessile and 2 pedicellate spikelets, if 1, the spikelet tangential to or embedded in the rachis, with 2 glumes, the glumes facing each other; ovaries with hairy apices; auricles often present (FNA 24:238) | Triticeae |
28. Inflorescences spikelike panicles with highly reduced branches, or spikes with spikelets radial to the rachises and all but the terminal spikelet with only 1 glume, or spikes with spikelets tangential to the rachises and having 2 glumes adjacent to each other; ovaries with glabrous apices; auricles usually absent (FNA 24:378) | Poeae |
26. Inflorescences panicles, with no sessile spikelets. | → 29 |
29. Caryopses with a thick pericarp forming a distinct apical knob or beak at maturity; lemmas 3(5)-veined (Pooideae, in part; FNA 24:64) | Diarrheneae |
29. Caryopses usually with a thin pericarp, never with a distinct apical beak or knob; lemmas 3-9-veined. | → 30 |
30. Glumes subulate, stiff; lemmas unawned or with awns to 4 mm long (Pooideae, in part; FNA 24:238) | Triticeae |
30. Glumes lanceolate, membranous; lemmas awned or unawned, awn length varied. | → 31 |
31. Rachillas hairy, hairs 2-3 mm long; lemmas coriaceous; plants established in California, sometimes cultivated as ornamentals (Pooideae, in part; FNA 24:109) | Stipeae |
31. Rachillas glabrous to hairy, hairs shorter than 2 mm; lemmas membranous to coriaceous; plants native, established, or cultivated. | → 32 |
32. Leaves to 2 cm wide, usually not conspicuously distichous; culms 0.01-2.75 m tall, usually less than 1 cm thick (Pooideae, in part; FNA 24:378) | Poeae |
32. Leaves 2-10 cm wide, often conspicuously distichous; culms 2-10(15) m tall, often more than 1 cm thick. | → 33 |
33. Lower cauline blades disarticulating, upper cauline blades forming a flat, fan-shaped arrangement (Panicoideae, in part; FNA 25:352) | Gynerieae |
33. Lower cauline blades persistent, upper cauline blades not forming a flat, fan-shaped arrangement (Arundinoideae, in part; FNA 25:7) | Arundineae |
1. All or almost all spikelets viviparous, the spikelets producing plantlets [if sexual spikelets are common, take the alternate lead]. | → 2 |
2. Panicle branches smooth or slightly scabrous, the scabrules widely spaced; blades with a translucent line on either side of the midvein, apices usually prowlike | Poa |
2. Panicle branches scabrous; blades without a translucent line on either side of the midvein, apices usually not prowlike. | → 3 |
3. Sheaths closed for 1/2 or more of their length; ligules 0.1-0.6 mm long | Festuca |
3. Sheaths open; ligules 1.5-13 mm long | Deschampsia |
1. Some, usually all, spikelets sexually functional, with 1-25 bisexual or unisexual florets, sometimes with sterile and sexual spikelets mixed within an inflorescence. | → 4 |
4. Inflorescences with 2 morphologically distinct forms of spikelets. | → 5 |
5. Spikelets in pairs, the pedicels not fused at the base, smooth or slightly scabrous; disarticulation above the glumes and beneath the florets | Cynosurus |
5. Spikelets in fascicles, the pedicels fused at the base, glabrous, hispid or strigose; disarticulation at the base of the fused pedicels. | → 6 |
6. Secondary panicle branches sharply bent below the pedicels; glumes not winged | Lamarckia |
6. Secondary panicle branches straight below the pedicels; glumes winged | Phalaris |
4. Inflorescences with all spikelets morphologically alike. | → 7 |
7. Glumes with pilose awns | Lagurus |
7. Glumes, if present, unawned or with glabrous awns. | → 8 |
8. Inflorescences spikes with 1-2(4) spikelets per node, or spikelike racemes with 1 spikelet at all or most nodes. | → 9 |
9. Spikelets with 1 functional floret, sometimes a reduced, sterile floret also present. | → 10 |
10. Glumes membranous, flexible; all spikelets pedicellate, pedicels 0.5-1 mm long, 0.1-0.2 mm thick | Mibora |
10. Glumes coriaceous, stiff; lower spikelets sessile, upper spikelets sometimes pedicellate. | → 11 |
11. Spikelets radial to the rachises, most spikelets with 1 glume, the terminal spikelets with 2 glumes | Hainardia |
11. Spikelets tangential to the rachises, all with 2 glumes. | → 12 |
12. Lemmas unawned | Parapholis |
12. Lemmas awned, awns 2-4 mm | Scribneria |
9. Spikelets with 2-25 functional florets. | → 13 |
13. Lemmas awned from about midlength, awns 8-26 mm long, twisted proximally. | → 14 |
14. Adaxial surfaces of the leaves ribbed; rachillas pilose on all sides; ligules truncate to rounded, 0.5-1.5 mm long | Helictotrichon |
14. Adaxial surfaces of the leaves unribbed; rachillas glabrous on the side adjacent to the paleas, hairy elsewhere; ligules acute to truncate, 0.5-7 mm long | Avenula |
13. Lemmas unawned or apically awned, awns straight. | → 15 |
15. Spikelets sessile; lemmas 2-12 mm long. | → 16 |
16. Spikelets radial to the rachises, most spikelets with 1 glume, only the terminal spikelet with 2 glumes | Lolium |
16. Spikelets tangential to the rachises, all spikelets with 2 glumes | Gaudinia |
15. Spikelets subsessile to pedicellate, pedicels 0.5-3 mm long. | → 17 |
17. Plants perennial | Festuca |
17. Plants annual. | → 18 |
18. Inflorescences usually exceeded by the leaves; spikelets with (2)3-4(7) florets; lemmas (5)7-9-veined, apices round to emarginate, not bifid; culms usually prostrate or procumbent | Sclerochloa |
18. Inflorescences usually exceeding the leaves; spikelets with 4-25 florets; lemmas 5-veined, apices acute to obtuse, sometimes bifid; culms procumbent to erect | Desmazeria |
8. Inflorescences panicles or racemes, with more than 1 spikelet associated with each node. | → 19 |
19. Inflorescences racemes or spikelike panicles, with all branches shorter than 1 cm [for opposite lead, see p. 382]. | → 20 |
20. Leaves usually exceeding the inflorescences; culms usually prostrate to procumbent; lemmas indurate at maturity | Sclerochloa |
20. Leaves usually exceeded by the inflorescences; culms usually erect or decumbent at the base; lemmas usually membranous or papery, sometimes coriaceous, not indurate. | → 21 |
21. Spikelets disarticulating below the glumes or, if the spikelets are attached to stipes, at the base of the stipes; glume bases sometimes fused. | → 22 |
22. Spikelets weakly laterally compressed, with stipes that fall with the spikelets; glume bases not fused; glumes usually awned | Polypogon |
22. Spikelets strongly laterally compressed, without stipes; glume bases sometimes fused; glumes unawned or awned. | → 23 |
23. Lemmas dorsally awned; spikelets oval in outline; glumes often connate at the base, often winged distally, keels sometimes ciliate, apices never abruptly truncate | Alopecurus |
23. Lemmas usually unawned, occasionally subterminally awned; spikelets often U-shaped in outline, sometimes oval; glumes not connate at the base, not winged, often strongly ciliate on the keels and abruptly truncate to an awnlike apex | Phleum |
21. Spikelets disarticulating above the glumes; glume bases not fused. | → 24 |
24. Spikelets with 2-25 bisexual florets, the sterile or staminate florets, if present, distal to the bisexual florets. | → 25 |
25. Sheaths closed for at least 1/2 their length. | → 26 |
26. Lemma midveins sometimes excurrent up to 2.2 mm, other veins not excurrent; plants native, arctic | Dupontia |
26. Lemmas with 3-5 veins excurrent, forming awnlike teeth; plants cultivated | Sesleria |
25. Sheaths open for all or almost all of their length. | → 27 |
27. Distal lemmas, sometimes all lemmas, awned from below midlength | Aira |
27. All lemmas unawned or apically awned. | → 28 |
28. Lemmas coriaceous at maturity, unawned, sometimes mucronate | Desmazeria |
28. Lemmas membranous, apically awned, awns 0.3-22 mm long. | → 29 |
29. Lemma margins involute, not scarious | Vulpia |
29. Lemma margins flat, scarious | Rostraria |
24. Spikelets with 1 bisexual floret, sometimes with 1-2 sterile florets below the bisexual floret, the sterile florets sometimes reduced to lemmas, sometimes resembling tufts of callus hair. | → 30 |
30. Spikelets with 1-2 sterile or staminate florets below the bisexual florets, these from larger than to much smaller than the bisexual florets, sometimes resembling tufts of hair; glumes sometimes winged distally. | → 31 |
31. Fresh leaves not sweet-smelling when crushed; sterile lemmas unawned; bisexual lemmas usually hairy, sometimes sparsely so; glumes subequal, sometimes winged distally | Phalaris |
31. Fresh leaves sweet-smelling when crushed; sterile lemmas awned; bisexual lemmas glabrous; glumes unequal, not winged | Anthoxanthum |
30. Spikelets without sterile or staminate florets below the bisexual floret; glumes not winged distally. | → 32 |
32. Lemmas dorsally awned, awns geniculate; lateral lemma veins excurrent, forming 4 teeth, teeth sometimes awnlike | Bromidium |
32. Lemmas unawned or with only 1 awn, awns not strongly geniculate; lateral lemma veins not excurrent. | → 33 |
33. Spikelets 8-15 mm long; lemmas more than 3/4 as long as the glumes; plants strongly rhizomatous | Ammophila |
33. Spikelets 1.2-7 mm long; lemmas less than 3/4 as long as the glumes; plants rhizomatous or not. | → 34 |
34. Sheaths closed for at least 1/2 their length. | → 35 |
35. Calluses glabrous; exposed at maturity; lemmas 1-3-veined, unawned; [other genera may develop long caryopses when infected by nematodes or fungi; such caryopses are usually deformed and filled with eggs, larvae, or spores] | Phippsia |
35. Calluses with a ring of stiff hairs, hairs to about 1 mm long; lemmas 3-11-veined | Dupontia |
34. Sheaths open for most of their length. | → 36 |
36. Spikelet bases usually U-shaped, sometimes cuneate; glumes equal, midveins usually strongly ciliate | Phleum |
36. Spikelet bases cuneate; glumes unequal, midveins not strongly ciliate. | → 37 |
37. Both glumes twice as long as the lemmas; lemmas pubescent | Gastridium |
37. Glumes from slightly shorter than to slightly longer than the lemmas; lemmas glabrous, sometimes scabridulous or scabrous. | → 38 |
38. Lemma awns 4-16 mm long; plants annual; paleas from 3/4 as long as to slightly longer than the lemmas | Apera |
38. Lemma awns to 10 mm, if longer than 4 mm, plants perennial and/or paleas less than 1/2 as long as the lemmas | Agrostis |
19. Inflorescences panicles, dense to open, sometimes compact, usually at least some branches longer than 1 cm [for opposite lead, see p. 380]. | → 39 |
39. Caryopses usually as long as or longer than the lemmas, exposed at maturity; lemmas 1-3-veined, unawned; spikelets with 1 floret; sheaths of the flag leaves closed for at least 1/2 their length; calluses glabrous [other genera may develop long caryopses when infected by nematodes or fungi; such caryopses are usually deformed or filled with eggs, larvae, or spores]. | → 40 |
40. Lemmas 1-veined, narrowed to awnlike apices; sheaths strongly inflated; glumes absent; plants of temperate habitats | Coleanthus |
40. Lemmas 1-3-veined, apices acute to rounded; sheaths not inflated; glumes developed, caducous or persistent; plants of arctic or alpine | Phippsia |
39. Caryopses shorter than the lemmas, concealed at maturity; lemmas 3-11-veined; spikelets with 1 or more florets; leaf sheaths open or closed; calluses glabrous or with hairs. | → 41 |
41. Panicle branches secund, appearing 1-sided; spikelets strongly imbricate, subsessile. | → 42 |
42. Culms usually prostrate or procumbent; glumes obtuse to emarginate | Sclerochloa |
42. Culms erect or ascending; glumes apiculate to awn-tipped. | → 43 |
43. Lemmas awned, awns of the lowest lemmas 0.3-22 mm long | Vulpia |
43. Lemmas unawned, sometimes awn-tipped. | → 44 |
44. Spikelets circular to ovate or obovate in outline, with 1-2 florets; glumes almost entirely concealing the sides of the florets; disarticulation below the glumes | Beckmannia |
44. Spikelets oval in outline, longer than wide, with 2-6 florets; glumes partially exposing the sides of the florets; disarticulation above the glumes | Dactylis |
41. Panicle branches not secund; spikelets usually widely spaced to somewhat imbricate, usually clearly pedicellate, sometimes subsessile, sometimes on stipes. | → 45 |
45. All or most spikelets in an inflorescence with 1 bisexual floret, sometimes with 1-2 sterile or staminate florets below the bisexual floret, the sterile florets sometimes resembling tufts of hair | Poeae Subkey I |
45. All or most spikelets in an inflorescence with 2-25 sexual florets, usually all florets bisexual or the distal florets sterile or unisexual, sometimes all florets unisexual, sometimes the plants unisexual | Poeae Subkey II |
POEAE SUBKEY I
1. Spikelets with 1-2 staminate or sterile florets below the bisexual floret, sterile florets sometimes knoblike or resembling tufts of hair. | → 2 |
2. Spikelets with 2 florets of similar size, the lower floret staminate; lower lemmas awned, the lemmas of the terminal floret unawned or awned | Arrhenatherum |
2. Spikelets with 2-3(4) florets, the lower 1-2 florets staminate or sterile, sometimes knoblike or resembling tufts of hair, sometimes larger than the bisexual floret; lemmas of the lower florets awned or unawned, the lemmas of the terminal floret unawned. | → 3 |
3. Lower sterile florets 2, from shorter than to exceeding the bisexual floret; fresh leaves sweet-smelling when crushed | Anthoxanthum |
3. Lower sterile florets 1-2, varying from knoblike projections on the callus of the bisexual floret to linear or lanceolate lemmas up to 3/4 as long as the bisexual floret; fresh leaves not sweet-smelling when crushed | Phalaris |
1. Spikelets without staminate or sterile florets below the bisexual florets. | → 4 |
4. Spikelets 15-50 mm long; lemmas usually dorsally awned, awns 20-90 mm long, sometimes unawned | Avena |
4. Spikelets 1-15 mm long; lemmas unawned or awned, awns to 18 mm long, basal, dorsal, subterminal, or terminal. | → 5 |
5. Glume bases gibbous and subcoriaceous; disarticulation above the glumes | Gastridium |
5. Glumes bases not gibbous, usually membranous; disarticulation above or below the glumes. | → 6 |
6. Lemmas awned, awns longer than 2 mm. | → 7 |
7. Glumes coriaceous, rigid, hispid or scabrous; lemmas awned, awns 5-14.5 mm long, subterminal | Limnodea |
7. Glumes membranous, flexible, glabrous or with soft hairs, usually smooth; lemmas awned, awns 0.5-18 mm long, sometimes subterminal. | → 8 |
8. Disarticulation below the glumes. | → 9 |
9. Spikelets borne on stipes; disarticulation at the base of the stipes; lemmas 0.5-2 mm long; glumes usually awned, sometimes unawned | Polypogon |
9. Spikelets borne on pedicels; disarticulation immediately below the glumes; lemmas 1.5-7.5 mm long; glumes usually unawned. | → 10 |
10. Paleas absent or greatly reduced; lemma awns attached at midlength or below; glume bases often fused; rachillas not prolonged beyond the floret base | Alopecurus |
10. Paleas from 3/4 to nearly as long as the lemmas; lemma awns subterminal; glume bases not fused; rachillas usually prolonged beyond the base of the distal floret as a minute stub or slender bristle | Cinna |
8. Disarticulation above the glumes. | → 11 |
11. Rachillas not prolonged beyond the base of the distal floret; paleas absent, minute, or subequal to the lemmas; lemmas 0.5-4 mm long. | → 12 |
12. Lemmas usually glabrous, sometimes pubescent, unawned or awned, if awned, the awns usually shorter than 4.5 mm, sometimes to 10 mm long, basal, dorsal, subterminal, or terminal; veins usually not excurrent, if excurrent, not forming awnlike teeth; panicles often open, sometimes contracted and cylindrical | Agrostis |
12. Lemmas pilose and dorsally awned, awns 4.5-6 mm long; lateral lemma veins excurrent, forming 4 teeth, teeth sometimes awnlike; panicles dense | Bromidium |
11. Rachillas prolonged beyond the base of the distal floret; paleas at least 1/2 as long as the lemmas; lemmas 1-8 mm long. | → 13 |
13. Plants annual; calluses glabrous or sparsely hairy; lemma apices entire; marginal veins not excurrent; awns subterminal | Apera |
13. Plants perennial; calluses usually abundantly, sometimes sparsely hairy, hairs 0.2-6.5 mm long; lemma apices denticulate or the marginal veins excurrent; awn attachment from nearly basal to subterminal. | → 14 |
14. Lemma surfaces mostly glabrous; lemma apices denticulate; marginal lemma veins not excurrent | Calamagrostis |
14. Lemma surfaces hairy; lemma apices erose or toothed; marginal lemma veins excurrent | Lachnagrostis |
6. Lemmas unawned or, if awned, awns shorter than 2 mm. | → 15 |
15. Disarticulation below the glumes. | → 16 |
16. Glumes attached to stipes, disarticulation at the base of the stipes; glumes usually awned, awns flexuous | Polypogon |
16. Glumes attached to pedicels, disarticulation immediately beneath the glumes; glumes unawned or with stiff awns. | → 17 |
17. Lemma awns subterminal; glume bases not fused; paleas from 3/4 to nearly as long as the lemmas; rachillas prolonged beyond the base of the distal floret for 0.1-1.3 mm | Cinna |
17. Lemma awns attached at midlength or below; glume bases often fused; paleas absent or greatly reduced; rachillas not prolonged beyond the base of the distal floret | Alopecurus |
15. Disarticulation above the glumes. | → 18 |
18. Glumes 8-15 mm long; plants strongly rhizomatous | Ammophila |
18. Glumes 1-10 mm long; plants rhizomatous or not. | → 19 |
19. Spikelets dorsally compressed; lemmas dark, coriaceous, lustrous, and glabrous | Milium |
19. Spikelets laterally compressed, sometimes weakly so; lemmas not simultaneously dark, coriaceous, lustrous, and glabrous. | → 20 |
20. Lower glumes exceeded by the florets, upper glumes exceeded by to exceeding the florets; sheaths usually closed for up to 1/5 their length | Arctagrostis |
20. Both glumes subequal to or exceeding the florets; sheaths open to the base. | → 21 |
21. Paleas absent or minute to subequal to the lemmas, not veined; rachillas not prolonged beyond the base of the distal florets; lemmas often unawned, sometimes awned, awn attachment basal to terminal | Agrostis |
21. Paleas more than 1/2 as long as the lemmas, 2-veined; rachillas prolonged beyond the base of the floret by at least 0.1 mm; lemmas often awned, awn attachment usually on the proximal 1/2 of the lemmas. | → 22 |
22. Calluses hairy, hairs 0.5-4.5 mm long; lemmas usually awned, awns usually attached to the proximal 1/2, if the attachment higher, the callus hairs longer than 2 mm and/or the awns geniculate | Calamagrostis |
22. Calluses glabrous or with hairs to about 1 mm long; lemmas unawned or terminally awned, awns to 1(2.2) mm long. | → 23 |
23. Glumes 4-9 mm long; sheaths closed for 1/2 - 2/3 their length; plants of arctic and subarctic regions | Dupontia |
23. Glumes 1.6-4.3 mm long; sheaths open; plants of western North America, from Alaska to California | Podagrostis |
POEAE SUBKEY II
1. One or both glumes exceeding the adjacent lemmas, sometimes exceeding the distal floret. | → 2 |
2. All lemmas within a spikelet unawned or with awns shorter than 2 mm. | → 3 |
3. Spikelets usually with 2 florets, lemmas of the lower florets unawned, lemmas of the upper florets awned, the awns strongly curved or hooked | Holcus |
3. Spikelets with 2-22 florets, all lemmas unawned or if awned, the awns straight. | → 4 |
4. Leaf sheaths closed for at least 1/2 their length; caryopses falling free of the lemma and palea; plants of arctic or subarctic regions. | → 5 |
5. Lemma apices obtuse; paleas subequal to the lemmas | Arctophila |
5. Lemma apices acute to acuminate; paleas shorter than the lemmas | Dupontia |
4. Leaf sheaths open for most of their length; caryopses usually falling with the lemma and palea attached; plants of temperate, arctic, or subarctic regions. | → 6 |
6. Glumes 15-50 mm long; plants annual | Avena |
6. Glumes 0.4-9 mm long; plants annual or perennial. | → 7 |
7. Lemmas inflated, about as wide as long, with broadly rounded backs; calluses glabrous; spikelets pendulous | Briza |
7. Lemmas not inflated, longer than wide, keeled to rounded over the midvein; calluses usually with hairs, sometimes glabrous; spikelets not pendulous. | → 8 |
8. Plants annual; spikelets with 2 florets; lemmas evenly hairy, 3-veined | Dissanthelium |
8. Plants usually perennial, sometimes annual; spikelets with 2-10 florets; lemmas usually glabrous or with unevenly distributed hairs, never both annual and with evenly distributed hairs, 3-9-veined. | → 9 |
9. Rachilla internodes hairy, hairs at least 1 mm long. | → 10 |
10. Lemma apices truncate, erose to 2-4-toothed | Deschampsia |
10. Lemmas apices acute, bifid | Trisetum |
9. Rachilla internodes glabrous or with hairs shorter than 1 mm on the distal portion. | → 11 |
11. Plants strongly rhizomatous; glumes 5-9 mm long | Scolochloa |
11. Plants not or weakly rhizomatous; glumes 0.4-9 mm long. | → 12 |
12. Panicle branches densely pubescent, hairs 0.1-0.2 mm long; lemma apices entire, sometimes mucronate; lemma veins converging distally | Koeleria |
12. Panicles branches glabrous, sometimes scabrous; lemma apices entire or serrate to erose, not mucronate; lemma veins more or less parallel distally | Puccinellia |
2. One or all lemmas within a spikelet awned, the awns at least 2 mm long. | → 13 |
13. Lemmas 14-40 mm long; glumes 7-11-veined | Avena |
13. Lemmas 1.3-16 mm long; glumes 1-9-veined. | → 14 |
14. Lemmas 7-16 mm long. | → 15 |
15. Adaxial surfaces of the leaves ribbed; rachillas pilose on all sides; ligules truncate to rounded, 0.5-1.5 mm long | Helictotrichon |
15. Adaxial surfaces of the leaves unribbed; rachillas glabrous on the side adjacent to the paleas, hairy elsewhere; ligules acute to truncate, 0.5-7 mm long | Avenula |
14. Lemmas 1.3-7 mm long. | → 16 |
16. Lemmas 1-veined, awned, awns articulated near the middle, the proximal segment yellow-brown to dark brown, the distal segment pale green to whitish, the junction marked by a ring of minute, conical protuberances | Corynephorus |
16. Lemmas 3-7-veined, at least some lemmas awned, awns not articulated. | → 17 |
17. Disarticulation below the glumes. | → 18 |
18. Spikelets usually with 2 florets, the lower florets bisexual with unawned lemmas, the upper florets staminate or sterile with awned lemmas | Holcus |
18. Spikelets with 2-5 florets, all florets bisexual or sometimes the distal florets sterile; all lemmas awned | Trisetum |
17. Disarticulation above the glumes. | → 19 |
19. Lowest lemma within a spikelet unawned or with a straight awn up to 4 mm long, the distal lemmas within a spikelet always awned, awns 10-16 mm long, geniculate | Ventenata |
19. All lemmas within a spikelet similarly awned or the awns of the lower lemmas longer than those of the upper lemmas, or the upper lemmas with awns shorter than 10 mm. | → 20 |
20. Callus hairs about 1/2 as long as the lemmas; rachillas not prolonged or prolonged about 0.5 mm or less beyond the base of the distal floret; plants loosely cespitose | Vahlodea |
20. Calluses usually glabrous or the hairs much shorter than 1/2 the length of the lemmas, if about 1/2 as long, the rachillas prolonged more than 0.5 mm beyond the base of the distal floret and the plants usually densely cespitose. | → 21 |
21. Plants annual; culms 1-60 cm tall; rachillas not prolonged beyond the base of the distal florets | Aira |
21. Plants perennial or annual; culms 5-150 cm tall; rachillas prolonged beyond the base of the distal florets, the prolongations hairy. | → 22 |
22. Rachilla internodes glabrous or with hairs shorter than 1 mm on the distal portion; panicle branches densely pubescent, not scabrous | Koeleria |
22. Rachilla internodes hairy, hairs at least 1 mm long; panicles branches usually glabrous, sometimes scabrous. | → 23 |
23. Lemma apices truncate, erose or 2-4-toothed | Deschampsia |
23. Lemmas apices acute, bifid | Trisetum |
1. Both glumes shorter than or subequal to the adjacent lemmas. | → 24 |
24. Upper lemma(s) in a spikelet with hooked or geniculate awns, awns 2-16 mm long; lowest lemmas unawned or terminally awned, awns straight, to 4 mm long. | → 25 |
25. Spikelets 9-15 mm long, with 2-20 florets; awns of the distal florets 10-16 mm long | Ventenata |
25. Spikelets 3-7 mm long, with 2 florets; awns of the distal floret 2-5 mm long | Holcus |
24. Lemmas all similarly awned or unawned. | → 26 |
26. Lower lemmas with awns longer than 2 mm. | → 27 |
27. Calluses hairy; rachillas prolonged beyond the base of the distal florets. | → 28 |
28. Glumes shorter than the adjacent lemmas; ligules 4.5-20 mm long | Amphibromus |
28. Glumes subequal to the adjacent lemmas; ligules 0.5-6 mm long | Trisetum |
27. Calluses glabrous or sparsely hairy; rachillas sometimes prolonged beyond the base of the distal florets. | → 29 |
29. Panicles dense, spikelike; plants annual | Rostraria |
29. Panicles not both dense and spikelike; plants perennial or annual. | → 30 |
30. Anthers 1; plants annual | Vulpia |
30. Anthers 3; plants perennial. | → 31 |
31. Leaves without auricles; blades flat, conduplicate, involute, or convolute | Festuca |
31. Lower leaves with auricles; blades flat | Schedonorus |
26. Lower lemmas unawned, mucronate, or with awns up to 2 mm long. | → 32 |
32. Lemmas inflated, about as wide as long; spikelets pendulous | Briza |
32. Lemmas not inflated, longer than wide; spikelets appressed to divergent, not pendulous. | → 33 |
33. Lemmas apices rounded, truncate, obtuse, or emarginate. | → 34 |
34. Lemmas conspicuously 3-veined; lower glumes 0-3-veined. | → 35 |
35. Lower glumes without veins; lemmas not keeled over the lateral veins | Catabrosa |
35. Lower glumes 1-3-veined; lemmas keeled over each vein | Cutandia |
34. Lemmas (3)5-9-veined, the veins often inconspicuous; lower glumes 1-5-veined. | → 36 |
36. Inflorescences usually exceeded by the leaves; lemmas indurate at maturity; pedicels 0.5-0.8 mm thick; culms usually prostrate to procumbent, sometimes ascending; upper glumes 2.6-6.2 mm long | Sclerochloa |
36. Inflorescences exceeding the leaves at maturity; lemmas usually membranous at maturity, sometimes coriaceous; pedicels less than 0.5 mm thick; culms usually erect; upper glumes 0.7-4.5(9) mm long. | → 37 |
37. Lower glumes about as long as the upper glumes but no more than 1/2 as wide; disarticulation below the glumes | Sphenopholis |
37. Lower glumes shorter than the upper glumes or subequal and more than 1/2 as wide; disarticulation above the glumes. | → 38 |
38. Sheaths closed for more than 1/2 their length | Arctophila |
38. Sheaths open their entire length. | → 39 |
39. Panicle branches stiff; lemmas coriaceous; plants annual; culms to 60 cm tall | Desmazeria |
39. Panicle branches flexible; lemmas usually membranous, sometimes coriaceous; plants usually perennial, sometimes annual or biennial; culms 2-145 cm tall. | → 40 |
40. Lemma veins excurrent, lemma apices indistinctly 3-lobed or toothed; plants strongly rhizomatous, rhizomes succulent | Scolochloa |
40. Lemma veins not excurrent, lemma apices entire, serrate, or erose; plants sometimes rhizomatous, rhizomes not succulent. | → 41 |
41. Lemma veins (5)7-9, prominent; plants of non-saline and non-alkaline habitats | Torreyochloa |
41. Lemma veins (3)5(7), inconspicuous or prominent; plants of saline and alkaline habitats | Puccinellia |
33. Lemma apices acute to acuminate, sometimes mucronate or shortly awn-tipped. | → 42 |
42. Lemmas (3)5-9-veined, veins more or less parallel distally, conspicuous. | → 43 |
43. Lemma veins (5)7-9; plants rhizomatous, growing in non-saline and non-alkaline habitats | Torreyochloa |
43. Lemma veins (3)5(7); plants not truly rhizomatous, sometimes the culms rooting at buried lower nodes, growing in saline and alkaline habitats | Puccinellia |
42. Lemmas 3-9-veined, veins converging distally, usually inconspicuous, sometimes conspicuous. | → 44 |
44. Lemmas conspicuously 3-veined, keeled over each vein; panicle branches divaricate; plants annual | Cutandia |
44. Lemmas inconspicuously (3)5-9-veined, sometimes keeled over the midvein, not over the other veins; panicle branches divaricate or not; plants annual or perennial. | → 45 |
45. Disarticulation below the glumes; lower glumes subequal to the upper glumes but no more than 1/2 as wide | Sphenopholis |
45. Disarticulation above the glumes, sometimes above the basal floret; lower glumes shorter than the upper glumes or, if subequal, more than 1/2 as wide. | → 46 |
46. Panicle branches smooth, hairy, hairs soft | Koeleria |
46. Panicle branches smooth or scabrous, glabrous or strigose, never covered with soft hairs. | → 47 |
47. Rachillas pilose, hairs at least 2 mm long (see Stipeae, p. 110) | Ampelodesmos |
47. Rachillas glabrous or with hairs shorter than 1 mm. | → 48 |
48. Basal leaves with auricles | Schedonorus |
48. No leaves with auricles. | → 49 |
49. Lemma veins parallel distally; plants of saline and alkaline habitats | Puccinellia |
49. Lemma veins converging distally; plants of many habitats, including saline habitats. | → 50 |
50. Leaf blades with translucent lines on either side of the midvein, apices often prow-tipped; lemmas often with a tuft of hair at the base of the midvein; hila round to oval | Poa |
50. Leaf blades without translucent lines on either side of the midvein, apices not prow-tipped, often flat; lemmas without a tuft of hair below the midvein hila usually linear, always linear in perennial species. | → 51 |
51. Plants perennial. | → 52 |
52. Plants and florets bisexual; glumes not translucent; caryopses obovoid-oblong | Festuca |
52. Plants unisexual; glumes translucent; caryopses fusiform | Leucopoa |
51. Plants annual. | → 53 |
53. Ligules up to 1 mm long; lemma apices mucronate or awned | Vulpia |
53. Ligules 1-4 mm long; lemma apices never awned, sometimes mucronate. | → 54 |
54. Panicle branches up to 2 cm long, stiff, spikelet-bearing to the base; culms procumbent to erect | Desmazeria |
54. Panicles branches 2-10 cm long, flexible, spikelets confined to the distal portion; culms erect | Eremopoa |
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