Poaceae tribe Paniceae
Panicum
panic grass, witchgrass
3-800 cm, annual, usually not woody.
2-300 cm, herbaceous, sometimes hard and almost woody, or woody, simple or branched, bases sometimes cormlike;
internodes solid, spongy, or hollow.
basal and/or cauline;
sheaths usually open;
ligules of hairs or membranous, membranous ligules often ciliate, cilia sometimes longer than the membranous base;
blades occasionally pseudopetiolate, seldom disarticulating at maturity.
cauline, basal, or both, basal leaves not forming a winter rosette;
ligules membranous, usually ciliate;
blades filiform to ovate, flat to involute, glabrous or pubescent, cross sections with Kranz anatomy and 1 or 2 bundle sheaths or with non-Kranz anatomy;
photosynthesis C4 with NAD-me or NADP-me pathways, or, in plants with non-Krantz anatomy, C3.
terminal, sometimes also axillary, occasionally subterranean panicles;
branches sometimes spikelike and secund, sometimes less than 1 cm;
disarticulation usually below the glumes, sometimes at the base of the panicle branches, occasionally below the florets.
terminal on the culms and branches, often also axillary, terminal panicles typically appearing after midsummer;
sterile branches and bristles absent;
disarticulation usually below the glumes, sometimes at the base of the upper florets, if at the base of the upper florets, then the florets not very plump at maturity.
usually dorsally compressed, varying to terete or laterally compressed, with 2(3) florets, lower florets staminate, sterile, or reduced, upper florets usually bisexual;
calluses not developed.
1-8 mm, usually dorsally compressed, sometimes subterete or laterally compressed, unawned.
usually membranous;
lower glumes usually less than 1/2 as long as the spikelets, sometimes absent;
upper glumes usually subequal to the upper florets, occasionally absent;
lower lemmas similar to the upper glumes in length and texture;
upper lemmas indurate, coriaceous, or cartilaginous, with a germination flap at the base, margins usually widely separated and involute at maturity, sometimes flat and hyaline;
upper paleas similar to the upper lemmas in length and texture;
lodicules short;
anthers usually 3;
stigmas usually red.
usually unequal, herbaceous, glabrous or pubescent, rarely tuberculate or glandular, apices not or only slightly gaping at maturity;
lower glumes minute to almost equaling the spikelets, 1-9-veined, truncate, acute, or acuminate;
upper glumes slightly shorter to much longer than the spikelets, 3-13(15)-veined, bases rarely slightly sulcate, apices rounded to attenuate;
lower florets sterile or staminate;
lower lemmas similar to the upper glumes;
lower paleas absent, or shorter than the lower lemmas and hyaline;
upper florets bisexual, sessile or stipitate, apices acute, puberulent, or with a tuft of hairs;
upper lemmas usually more or less rigid and chartaceous-indurate, usually shiny, glabrous or (rarely) pubescent, usually smooth, sometimes verrucose or transversely rugose, margins involute, usually clasping the paleas, rarely with basal wings or lunate scars, apices obtuse, acute, apiculate, or with small green crests;
upper paleas striate, rarely transversely rugose;
lodicules 2;
anthers usually 3.
usually dorsally compressed or terete;
embryos 1/2 or more the length of the caryopses.
smooth;
pericarp thin;
endosperm hard, without lipid, starch grains simple or compound, or both;
hila round or oval, x = 9 (usually), sometimes 10, with polyploid and dysploid derivatives.
= 9, 10.
Poaceae tribe Paniceae
Panicum
The tribe Paniceae, which includes about 100 genera and 2000 species, is primarily tropical in distribution. Within the Flora region, it is represented by 27 genera and 262 species, with its greatest representation being in the eastern portion of the contiguous United States (Barkworth and Capels 2000).
The tribe is so morphologically distinct that it was first recognized, in essentially its current sense, by Robert Brown in 1814. Its primary distinguishing features are the unusual spikelet structure combined with the indurate to coriaceous upper florets. Recent molecular studies (Barber et al. 2002; Guissani et al. 2001) show it as comprising two distinct lineages, one of which contains species with a base number of x = 9 and the other, species with x = 10.
Photosynthesis in the Paniceae may follow the C3 pathway or any of three different C4 pathways. Most genera are uniform in this regard, but there are some noteworthy exceptions. Guissani et al. (2001) concluded that the C3 pathway is probably ancestral within the tribe and that two of the three C4 pathways, NAD-ME and PCK, originated only once within the tribe, whereas the NADP-ME pathway originated independently in several different lineages. Most genera are uniform with respect to their photosyntheticd pathway, but there are some noteworthy exceptions.
The germination flap is a small area of soft tissue at the base of the upper lemma through which the primary root of the seedling grows.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Panicum is a large genus, but just how large is difficult to estimate because its limits are not yet clear. Many taxonomists would treat it as including Dichanthelium, Steincbisma, and some members of Urochloa. Recent work supports some aspects of the treatment presented here, but not all of them. For instance, Guissani et al. (2001) suggest that Panicum subg. Panicum is a monophyletic group that should have a rank equivalent to Dichanthelium and Steinchisma. The two other subgenera included here in Panicum, subg. Agrostoidea and subg. Phanopyrum, are not monophyletic, but the relationships of their species to other members of Panicum sensu lato are not well enough understood to suggest a better treatment, nor to justify the name changes a differing generic treatment would require.
Most species of Panicum are tropical, but many grow in warm, temperate regions. Of the thirty-four species occurring in the Flora region, twenty-five are native, seven are established introductions, and two are not established within the region. Within the Flora region, Panicum is most abundant in the southeastern United States. Many species grow in early serai stages or weedy areas; some grow at forest edges, in prairies, savannahs, deserts, forests, beaches, and in shallow water.
Panicum miliaceum has been grown since prehistory in China and India as a cereal grain, and is a common component of bird seed. Seeds of P. hirticaule subsp. sonorum have been used for food by the Cocopa tribe of the southwest. Important hay and range species include P. virgatum, P. rigidulum, P. bulbosum, P. obtusum, and P. repens.
Apomixis, polyploidy, and autogamy have produced numerous microspecies in some groups; hybridization and introgression has resulted in a reticulum of intergrading forms in some complexes. The number of taxa recognized has varied widely over the past century.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Plants developing both subterranean and aerial inflorescences, only the subterranean spikelets setting seed | Amphicarpum |
1. Plants developing only aboveground inflorescences, the spikelets setting seed [Amphicarpum is also keyed out here to accommodate situations in which looking for subterranean inflorescences is not permitted or specimens have no underground parts]. | → 2 |
2. Inflorescences spikelike panicles, with the branches partially embedded in the flattened rachises; plants perennial, stoloniferous | Stenotaphrum |
2. Inflorescences panicles, sometimes spikelike, but the branches not embedded in the rachises or the rachises not flattened; plants annual or perennial, sometimes stoloniferous. | → 3 |
3. Most spikelets or groups of 2-11 spikelets subtended by 1-many, distinct to more or less connate, stiff bristles or bracts. | → 4 |
4. Spikelets in groups of 2-11, subtended by 4 flat, narrowly elliptic, coriaceous bracts; terete bristles not present | Anthephora |
4. Spikelets solitary or in groups, subtended by 1-many stiff, terete bristles, sometimes appearing as an extension of the branch; flat, connate bristles sometimes present distal to the terete bristles. | → 5 |
5. Bristles falling with the spikelets at maturity; disarticulation at the base of the reduced panicle branches (fascicles). | → 6 |
6. Bristles plumose or antrorsely scabrous, free or fused no more than 1/2 their length | Pennisetum |
6. Bristles glabrous, smooth, retrorsely scabrous, or strigose, usually at least some bristles fused for more than 1/2 their length | Cenchrus |
5. Bristles persistent; disarticulation below the spikelets. | → 7 |
7. Upper glumes indurate at maturity; lower lemmas somewhat indurate at the base; pedicels subtended by a single bristle | Setariopsis |
7. Upper glumes membranous to herbaceous at maturity; lower lemmas neither constricted nor indurate at the base; pedicels subtended by 1-many bristles. | → 8 |
8. Spikelets subtended by 1-many bristles; paleas of the lower florets usually hyaline to membranous at maturity, rarely absent or reduced; paleal veins not keeled | Setaria |
8. Spikelets subtended by 1 bristle; paleas of the lower florets coriaceous to indurate at maturity, the keels thickened | Ixophorus |
3. All or most spikelets not subtended by stiff bristles, sometimes the terminal spikelet on each branch subtended by a single bristle, and occasionally other spikelets with a single subtending bristle. | → 9 |
9. Terminal spikelet on each branch subtended by a single bristle; other spikelets occasionally with a single stiff subtending bristle | Setaria |
9. None of the spikelets subtended by a stiff bristle. | → 10 |
10. Inflorescences of spikelike branches 1-3.7 cm long, the branch axes extending as a 2.5-4 mm bristle beyond the base of the distal spikelets | Paspalidium |
10. Inflorescences various but, if of spikelike branches, these terminating in a well-developed or rudimentary spikelet. | → 11 |
11. Lower glumes or lower lemmas awned, sometimes shortly so (the awn reduced to a point in Echinochloa colona). | → 12 |
12. Upper florets laterally compressed; spikelets also laterally compressed | Melinis |
12. Upper florets dorsally compressed; spikelets usually dorsally compressed or terete, sometimes laterally compressed. | → 13 |
13. Blades linear to linear-lanceolate, usually more than 10 times longer than wide, with prominent midribs; at least the upper leaves, often all leaves, without ligules; ligules usually absent, particularly from the upper leaves, of hairs when present | Echinochloa |
13. Blades triangular to lanceolate, less than 10 times longer than wide, the midribs not particularly prominent, at least distally; ligules present, of hairs or membranous. | → 14 |
14. Lower glumes awned, the awns exceeding the florets; upper glumes not ciliate-margined; culms trailing on the ground, frequently rooting and branching at the nodes | Oplismenus |
14. Lower glumes unawned or shortly awned, the awns exceeded by the florets; upper glumes ciliate-margined; culms erect or decumbent below, sometimes rooting and branching at the lower nodes | Alloteropsis |
11. Lower glumes and lower lemmas unawned. | → 15 |
15. Upper florets laterally compressed | Melinis |
15. Upper florets dorsally compressed or terete. | → 16 |
16. Upper lemmas and paleas cartilaginous and flexible at maturity; lemma margins flat, hyaline; lower glumes absent or to 1/4 the length of the spikelets. | → 17 |
17. Aerial inflorescences with elongate rachises and glabrous spikelets; spikelets of the aerial panicles rarely setting seed; subterranean spikelets developed, seed-forming | Amphicarpum |
17. Aerial inflorescences of digitate or subdigitate clusters of spikelike branches with glabrous or pubescent spikelets or with elongate rachises and conspicuously pubescent spikelets; aerial spikelets seed-forming; subterranean spikelets not developed. | → 18 |
18. Spikelets ellipsoid to obovoid; inflorescences simple panicles with erect to ascending branches on elongate rachises; branches ascending, not conspicuously spikelike | Anthenantia |
18. Spikelets lanceoloid to ellipsoid; inflorescences usually panicles with digitate or subdigitate clusters of spikelike branches, sometimes simple panicles with strongly divergent branches | Digitaria |
16. Upper lemmas and paleas chartaceous to indurate and rigid at maturity; lemma margins not hyaline, frequently involute; lower glumes varying from absent to subequal to the spikelets or extending beyond the distal floret. | → 19 |
19. Spikelets subtended by a cuplike callus | Eriochloa |
19. Spikelets not subtended by a cuplike callus. | → 20 |
20. At least the upper leaves, often all leaves, without ligules; ligules, when present, of hairs | Echinochloa |
20. All leaves with ligules, ligules membranous or of hairs. | → 21 |
21. Paleas of the lower florets inflated and indurate at maturity; lower and upper florets standing apart from each other when mature | Steinchisma |
21. Paleas of the lower florets neither inflated nor indurate at maturity; lower and upper florets closely appressed to each other when mature, [revert to left side] | → 22 |
22. Inflorescences of 1-sided, spikelike primary branches. | → 23 |
23. Spikelets with the lower lemmas and lower glumes (if present) adjacent to the branch axes. | → 24 |
24. Lower glumes absent | Axonopus |
24. Lower glumes present on all or most spikelets. | → 25 |
25. Upper lemmas rugose and verrucose; panicle branches in 2 or more ranks, sometimes verticillate | Urochloa |
25. Upper lemmas smooth; panicle branches in 1 rank | Moorochloa |
23. Spikelets with the upper lemmas and upper glumes (if present) adjacent or appressed to the branch axes. | → 26 |
26. Both glumes absent from all or almost all spikelets, the terminal spikelet on a branch sometimes with upper glumes | Reimarochloa |
26. Upper or both glumes present on all spikelets. | → 27 |
27. Upper lemmas smooth to slightly rugose; lower glumes usually absent | Paspalum |
27. Upper lemmas rugose and verrucose; lower glumes present, from 1/5 as long as the spikelets to equaling them | Urochloa |
22. Inflorescences usually panicles with well-developed secondary branches, sometimes spikelike panicles or panicles with spikelike, but not 1-sided, branches. | → 28 |
28. Inflorescences dense, the spikelets concealing at least the distal 1/2 of the rachises. | → 29 |
29. Upper glumes slightly to strongly saccate, 5-13-veined; panicle branches often fused to the rachises; blades 1.5-22 mm wide; culm internodes hollow | Sacciolepis |
29. Upper glumes not saccate, 3-7-veined; panicle branches not fused to the rachises; blades 12-28 mm wide; culm internodes filled with aerenchyma | Hymenachne |
28. Inflorescences more or less open panicles, the spikelets not concealing the rachises. | → 30 |
30. Lower glumes with saccate bases; glumes and lemmas with woolly pubescent apices; culms weakly lignified, rooting at the nodes | Lasiacis |
30. Lower glumes not saccate basally; glumes and lemmas glabrous or with short, straight hairs, apices sometimes with a tuft of hairs but never woolly pubescent; culms usually not lignified, if lignified, not rooting at the nodes. | → 31 |
31. Lemmas of the upper florets rugose and verrucose; panicle branches usually spikelike and 1-sided, alternate or subopposite, less frequently verticillate | Urochloa |
31. Lemmas of the upper florets usually smooth, if rugose the panicle branches neither verticillate nor 1-sided and spikelike. | → 32 |
32. Plants developing aerial and subterranean panicles; aerial spikelets lanceoloid, often without lower glumes; upper lemmas with flat margins | Amphicarpum |
32. Plants developing aerial, but not subterranean, panicles; spikelets ovoid to ellipsoid or lanceoloid; lower glumes present; upper lemmas with involute margins. | → 33 |
33. Blades of the basal leaves clearly distinct from the cauline leaves; basal leaves ovate to lanceolate, cauline leaves with longer and narrower blades; basal leaves forming a distinct winter rosette | Dichanthelium |
33. Blades of the basal and cauline leaves similar, usually linear to lanceolate, varying from filiform to ovate; basal leaves not forming a distinct winter rosette. | → 34 |
34. Panicles terminating the culms usually appearing in late spring; branches usually developing from the lower and middle cauline nodes in summer, the branches rebranching 1 or more times by fall; upper florets not disarticulating at maturity, plump | Dichanthelium |
34. Panicles terminating the culms usually appearing after midsummer; branches usually not developing branches from the lower and middle cauline nodes, when present, rarely rebranched; upper florets disarticulating or not very plump at maturity | Panicum |
1. Panicle branches 1-sided; spikelets usually subsessile, the longest pedicels usually less than 2 mm long, rarely 3 mm long. | → 2 |
2. Spikelets 5.5-7 mm long; upper florets less than 1/3 as long as the spikelets (sect. Phanopyrum) | P. gymnocarpon |
2. Spikelets 1.6-4.4 mm long; upper florets 2/5 as long as to almost equaling the spikelets. | → 3 |
3. Lower glumes 5- or 7-veined, about 3/4 as long as the spikelets; plants with stolons or shallow rhizomes (sect. Obtusa) | P. obtusum |
3. Lower glumes 1- or 3-veined, 1/2 - 2/3 as long as the spikelets; plants without stolons, often with rhizomes. | → 4 |
4. Lower florets staminate; lower paleas subequal to the lower lemmas; upper thin, lemmas flexible, clasping the paleas only at the base (sect. Hemitonia) | P. hemitomon |
4. Lower florets sterile; lower paleas no more than 2/3 as long as the lower lemmas; upper lemmas thick, stiff, clasping the paleas throughout their length. | → 5 |
5. Glumes and lower lemmas without keeled midveins; upper florets with glabrous apices; plants tufted, from knotty rhizomes; panicles with a few spikelets; pedicels with slender hairs near the apices (sect. Tenera) | P. tenerum |
5. Glumes and lower lemmas with keeled midveins; upper florets with a tuft of small hairs at the apices; plants often with scaly rhizomes; panicles with many spikelets; pedicels glabrous (sect. Agrostoidea). | → 6 |
6. Plants without conspicuous rhizomes, cespitose; culms and sheaths strongly compressed; spikelets usually 1.6-3.8 mm long, lanceolate, not falcate | P. rigidulum |
6. Plants with conspicuous, stout, short or elongate, scaly rhizomes; culms and sheaths slightly compressed; spikelets 2.3-3.9 mm long, rarely lanceolate, often falcate | P. anceps |
1. Panicle branches usually not 1-sided; spikelets not subsessile, the longest pedicels 2-20 mm long. | → 7 |
7. Upper glumes and lower lemmas warty-tuberculate (sect. Verrucosa). | → 8 |
8. Lower lemmas verrucose with hemispheric warts; spikelets 1.7-2.2 mm long, about 1 mm wide, subacute or obtuse, glabrous; plants of wetlands | P. verrucosum |
8. Lower lemmas tuberculate-hispid; spikelets 3.2-4 mm long, about 1.5 mm wide, acute or acuminate; plants of dry, sandy or clayey areas | P. brachyanthum |
7. Upper glumes and lower lemmas glabrous, villous, or scabridulous, but not warty-tuberculate. | → 9 |
9. Upper florets faintly to evidently transversally rugose; sheaths keeled; culm bases often cormlike (sect. Bulbosa). | → 10 |
10. Culm bases thickened, cormlike; culms slightly compressed; rhizomes, if present, short and thin; spikelets 2.8-5.4 mm long; lower glumes 1.2-3.5 mm long, 1/2 - 4/5 as long as the spikelets | P. bulbosum |
10. Culm bases not cormlike; culms strongly compressed; rhizomes present, long, stout; spikelets 2.5-3.4 mm long; lower glumes usually less than 1.7 mm long, up to 1/2 as long as the spikelets | P. plenum |
9. Upper florets smooth or striate, rarely inconspicuously rugose; sheaths not keeled; culm bases never cormlike. | → 11 |
11. Plants with rhizomes about 1 cm thick and with large, pubescent, scalelike leaves; culms hard, almost woody (sect. Antidotalia) | P. antidotale |
11. Plants without rhizomes or with rhizomes less than 0.5 cm thick and with small, glabrous, scalelike leaves; culms clearly not woody, except at the base of P. hirsutum (subg. Panicum). | → 12 |
12. Glumes, lower lemmas, and upper lemma margins villous, with whitish hairs (sect. Urvilleana) | P. urvilleanum |
12. Glumes and lemmas usually glabrous, sometimes the lower lemmas sparsely pilose on the margins and near the apices. | → 13 |
13. Plants perennial, usually with vigorous scaly rhizomes; lower florets staminate (sect. Repentia). | → 14 |
14. Lower glumes 0.5-1.5 mm long, less than 1/2 as long as the spikelet, 1-5-veined; upper glumes and lower lemmas extending 0.1-0.5 mm beyond the upper florets and scarcely separated (gaping); lower paleas oblong, not hastate-lobed. | → 15 |
15. Lower glumes subtruncate to broadly acute, faintly veined; upper florets widest at or above the middle, with rounded apices; plants not cespitose, with long, scaly rhizomes | P. repens |
15. Lower glumes acute, with evident veins; upper florets widest below the middle, with lightly beaked apices; plants cespitose, with short knotty rhizomes | P. coloratum |
14. Lower glumes 1.8-4 mm long, more than 1/2 as long as the spikelets, with at least 5 veins; upper glumes and lower lemmas extending 0.4-3 mm beyond the upper florets, stiffly separated (gaping); lower paleas hastate-lobed. | → 16 |
16. Panicles contracted; branches appressed to strongly ascending; plants glabrous throughout | P. amarum |
16. Panicles open; branches ascending to spreading; plants often pilose, at least at the base of the leaf blades | P. virgatum |
13. Plants annual, or perennials usually without rhizomes, sometimes rooting at the lower nodes; lower florets sterile. | → 17 |
17. Lower glumes truncate to subacute, 1/5 – 1/3 as long as the spikelets; sheaths more or less compressed, glabrous or sparsely pubescent; plants slightly succulent or spongy (sect. Dichotomiflora). | → 18 |
18. Plants usually annual, usually terrestrial, rooting at the lower nodes if in water, but not floating; blades 3-25 mm wide | P. dichotomiflorum |
18. Plants perennial or of indefinite duration, usually aquatic, sometimes floating, rooting at the lower nodes; blades 2-15 mm wide. | → 19 |
19. Spikelets 2-2.2 mm long; blades 2-4 mm wide; lower paleas absent; culms succulent | P. lacustre |
19. Spikelets 3-4 mm long; blades 5-15 mm wide; lower paleas present; culms spongy | P. paludosum |
17. Lower glumes acute to attenuate, usually 1/3 – 3/4 as long as the spikelets; sheaths rounded, usually hirsute or hispid; plants not succulent (sect. Panicum). | → 20 |
20. Spikelets 4-6.5 mm long. | → 21 |
21. Upper glumes and lower lemmas only slightly exceeding the upper florets; upper florets 2-2.5 mm wide; plants annual; lower paleas truncate to bilobed | P. miliaceum |
21. Upper glumes and lower lemmas exceeding the upper florets by 3-4 mm; upper florets 1-1.1 mm wide; plants perennial; lower paleas acute | P. capillarioides |
20. Spikelets 1-4.2 mm long. | → 22 |
22. Plants perennial; panicle branches usually with all or most secondary branches confined to the distal 1/3. | → 23 |
23. Lower panicle branches whorled; culms 2-10 mm thick, 50-300 cm tall. | → 24 |
24. Sheaths with fragile, prickly hairs causing skin irritation; panicles not breaking at the base and becoming tumble-weeds; lower paleas 1.3-1.7 mm long | P. hirsutum |
24. Sheaths glabrous or sparsely to densely pubescent but without fragile, prickly hairs; panicles breaking at the base and becoming tumbleweeds; lower paleas 1.4-2.2 mm long | P. bergii |
23. Lower panicle branches solitary; culms 0.5-10 mm thick, 15-100 cm tall. | → 25 |
25. Blades glabrous and glaucous on the adaxial surface; nodes sericeous or pilose, sometimes almost glabrous | P. ballii |
25. Blades sparsely to densely hirsute and not glaucous on the adaxial surface; nodes sericeous. | → 26 |
26. Spikelets 2.1-2.9 mm long; culms spreading to weakly ascending; blades spreading, 1-5 mm wide, without a prominent white midrib | P. diffusum |
26. Spikelets 2.6-3.4 mm long; culms erect to decumbent; blades ascending to erect, 0.5-14 mm wide, with a prominent white midrib | P. ghiesbreghtii |
22. Plants annual; panicle branches usually with secondary branches and pedicels attached to the distal 2/3 | → 27 |
27. Blades 2-7 cm long, 5-20 mm wide, lanceolate, 4-6 times longer than wide (sect. Monticola, in part) | P. trichoides |
27. Blades 5-40 cm long, 1-18 mm wide, linear, more than 10 times longer than wide (sect. Panicum, in part). | → 28 |
28. Panicles more than 2 times longer than wide at maturity; branches ascending to somewhat divergent; spikelets narrowly ovoid, usually about 3 times longer than wide | P. flexile |
28. Panicles less than 1.5 times longer than wide at maturity; branches diverging; spikelets variously shaped, less than 3 times longer than wide. | → 29 |
29. Spikelets 2.1-4 mm long, upper glumes and lower lemmas with prominent veins; lower glumes 2/5 – 3/4 as long as the spikelets; lower paleas 0.4-2 mm long, from 1/3 as long as the lower lemmas to equaling them; ligules 0.2-0.4 mm or 1-3.5 mm long. | → 30 |
30. Lower glumes 0.7-1.1 mm long, about 2/5 as long as the spikelets; lower paleas 1-2 mm long; leaf blades 2-8 mm wide, usually completely glabrous, sometimes with a few marginal cilia near the base | P. psilopodium |
30. Lower glumes 1.2-2.4 mm long, 1/2 - 3/4 as long as the spikelets; lower paleas 0.2-0.9 mm long; leaf blades 1-30 mm wide, hairs papillose-based. | → 31 |
31. Primary panicle branches appressed to the main axis; culms 2-8 cm long; spikelets 2-2.2 mm long | P. mobavense |
31. Primary panicle branches divergent; culms 11-110 cm long; spikelets 1.9-4 mm long | P. hirticaule |
29. Spikelets 1.4-4 mm long, upper glumes and lower lemmas without prominent veins; lower glumes usually less than 1/2 as long as the spikelets; lower paleas usually small or absent; ligules 0.5-1.5 mm long. | → 32 |
32. Plants mostly glabrous, but the sheaths ciliate on the margins and the blades sometimes sparingly pilose adaxially (sect. Monticola, in part) | P. bisulcatum |
32. Plants mostly hairy, even the sheaths hairy throughout. | → 33 |
33. Panicles usually more than 1/2 the total height of the plant, breaking at the base of the peduncle at maturity and becoming a tumbleweed; spikelets 1.9-4 mm long; mature upper florets stramineous or nigrescent (sect. Panicum, in part) | P. capillare |
33. Panicles usually less than 1/2 the total height of the plant, the base of the peduncle usually not breaking at maturity; spikelets 1.4-2.4 mm long; mature upper florets often dark brown | P. philadelphicum |
- Local floras:
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
IL Wildflowers, 
KS Wildflowers, 
LA Plants, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
