Flora of North America species comparison

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Paspalum

Paspalum setaceum

crowngrass, paspalum

fringeleaf paspalum, sand paspalum, slender beadgrass, slender crown grass, thin paspalum
Habit Plants annual or perennial; cespitose, rhizomatous, or stoloniferous. Plants perennial; cespitose or shortly rhizomatous.
Culms

3-400 cm, erect, spreading or prostrate, sometimes trailing for 200+ cm.

25-110 cm, erect, spreading, or prostrate;

nodes glabrous or pubescent.
Sheaths

open;

auricles sometimes present;

ligules membranous.

glabrous or pubescent;

ligules 0.2-0.5 mm;

blades flat, glabrous or pubescent.
Panicles

terminal and axillary, with 1-6 racemosely axillary arranged branches, panicles partially or completely enclosed by the subtending leaf sheath;

branches 2-12(17) cm, ascending to spreading, often arcuate, terminating in a spikelet;

branch axes 0.2-1.2 mm wide, glabrous, sometimes scabrous.
Inflorescences

terminal, sometimes also axillary, panicles of 1-many spikelike branches, these digitate or racemose on the rachis, spreading to erect, 1 or more branches completely or partially hidden in the sheaths in some species;

branch axes flattened, usually narrowly to broadly winged, usually terminating in a spikelet, sometimes extending beyond the distal spikelet but never forming a distinct bristle;

disarticulation below the glumes.

Spikelets

subsessile to shortly pedicellate, plano-convex, rounded to acuminate, dorsally compressed, not subtended by bristles or a ringlike callus, solitary or paired (1 spikelet of the pair reduced in some species), in 2 rows along 1 side of the branches, with 2 florets, first rachilla segment not swollen, upper glumes and upper lemmas adjacent to the branch axes;

lower florets sterile;

upper florets sessile or stipitate, bisexual, acute or rounded.

1.4-2.6 mm long, paired, imbricate, appressed to the branch axes, elliptic to obovate to ovate to orbicular, stramineous or brown.
Lower glumes

absent or present only on some spikelets of each branch, without veins or 1-veined, unawned;

upper glumes and lower lemmas subequal, membranous, apices rounded, unawned;

lower paleas absent or rudimentary;

upper lemmas convex, indurate, smooth to slightly rugose, stramineous to dark brown, margins scarious, involute, clasping the paleas;

upper paleas indurate, smooth to slightly rugose, stramineous to dark brown.

absent;

upper glumes and lower lemmas glabrous or shortly glandular-pubescent, 3-veined, margins entire;

lower lemmas lacking ribs over the veins;

upper florets stramineous.
Caryopses

orbicular to elliptical, plano-convex or flattened, white, yellow, or brown, x = 10, 12.

elliptic to suborbicular, white.
2n

= 20.

Paspalum

Paspalum setaceum
Distribution
from FNA
AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; MI; MN; MO; MS; MT; NC; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; HI; PR; ON; Virgin Islands
[BONAP county map]
from FNA
AL; AR; AZ; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; MI; MN; MO; MS; MT; NC; NE; NH; NJ; NM; NY; OH; OK; PA; RI; SC; SD; TN; TX; VA; VT; WI; WV; PR; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

Paspalum includes 300-400 species, most of which are native to the Western Hemisphere. Forty-three species are found in the Flora region; twenty-four are native. Paspalum scrobiculatum is grown as a grain in India, and several species are grown as forage plants. There are also many weedy species in the genus. Nineteen of the species growing in the Flora region are introduced, and some of them are weedy. Because weeds are under-represented in most herbaria, the distribution maps of such species probably understate their prevalence.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Paspalum setaceum is a variable species that grows east of the Rocky Mountains in the contiguous United States and Mexico. The following treatment summarizes the major patterns of variation within the species. Some specimens will be hard to place, particularly old herbarium specimens that have lost their color. Nine varieties grow in the Flora region.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Spikelets solitary, not associated with a naked pedicel or rudimentary spikelets.
→ 2
2. Panicles with 1-70 branches, if more than 1, the branches racemosely arranged.
→ 3
3. Branches 7-70, disarticulating at maturity, the axes extending beyond the distal spikelets
P. repens
3. Branches 1-6, persistent, terminating in a spikelet.
→ 4
4. Upper florets olive to dark brown
P. scrobiculatum
4. Upper florets pale to stramineous.
→ 5
5. Axes of panicle branches 0.6-1.3 mm wide
P. laeve
5. Axes of panicle branches 1.8-3.3 mm wide.
→ 6
6. Spikelets 1.7-2.1 mm long; upper lemmas glabrous throughout
P. dissectum
6. Spikelets 3.2-4 mm long; upper lemmas with a few short hairs at the apices
P. acuminatum
2. Panicles usually composed of a terminal pair of branches, sometimes with 1(-5) additional branches below the terminal pair.
→ 7
7. Upper glumes pilose on the margins or shortly pubescent on the back.
→ 8
8. Spikelets 1.3-1.9 mm long; upper glumes pilose along the margins
P. conjugatum
8. Spikelets 2.4-3.2 mm long; upper glumes sparsely short pubescent on the back
P. distichum
7. Upper glumes glabrous.
→ 9
9. Spikelets elliptic, their apices acute to acuminate.
→ 10
10. Plants rhizomatous, not appearing cespitose; usually in brackish to salt marsh habitats
P. vaginatum
10. Plants shortly rhizomatous but appearing cespitose; usually in disturbed inland habitats
P. almum
9. Spikelets ovate to broadly elliptic, their apices obtuse to broadly acute.
→ 11
11. Spikelets 2.5-4 mm long; leaf blades flat or conduplicate
P. notatum
11. Spikelets 1.9-2.3 mm long; leaf blades flat
P. minus
1. Spikelets paired, if only 1 spikelet functional, a naked pedicel or rudimentary, non-functional spikelet present.
→ 12
12. Spikelets 1-1.3 mm long.
→ 13
13. Panicle branches 2-6; spikelets elliptic to elliptic-obovate, appressed to the branch axes
P. blodgettii
13. Panicle branches 18-50; spikelets ovate, diverging from the branch axes
P. paniculatum
12. Spikelets 1.3-4.1 mm long.
→ 14
14. Margins of upper glumes and lower lemmas ciliate-lacerate and winged or pilose.
→ 15
15. Upper glumes and lower lemmas ciliate-lacerate, winged
P. fimbriatum
15. Upper glumes and lower lemmas pilose.
→ 16
16. Panicle branches 2-7; spikelets 2.3-4 mm long
P. dilatatum
16. Panicle branches (4)10-30; spikelets 1.8-2.8 mm long
P. urvillei
14. Margins of upper glumes and lower lemmas neither ciliate-laceerate nor winged, glabrous or pubescent, if pubescent then the hairs not pilose, often glandular, papillose-based, or wrinkled.
→ 17
17. Upper florets olive to dark brown.
→ 18
18. Plants aquatic, the culms decumbent, rooting at the nodes; lower glumes often present
P. modestum
18. Plants not aquatic or, if aquatic, the culms erect; lower glumes absent.
→ 19
19. Panicle branches 10-28 or more.
→ 20
20. Plants annual; axes of panicle branches broadly winged, wings about as wide as the central portion
P. boscianum
20. Plant perennial; axes of panicle branches narrowly winged, wings narrower than the central portion.
→ 21
21. Axes of panicle branches 1-1.7 mm wide; spikelets 1.8-2.4 mm wide
P. virgatum
21. Axes of panicle branches 0.5-1.2 mm wide; spikelets 1.1-1.8 mm wide
P. conspersum
19. Branches 1-10(28).
→ 22
22. Plants annual.
→ 23
23. Spikelets 1.3-1.8 mm wide, broadly elliptical to orbicular, glabrous; panicles with 1-10(28) branches, the axes 0.7-2.3 mm wide
P. boscianum
23. Spikelets 1.7-2.4 mm wide, broadly obovate, shortly pubescent; panicles with 1-5 branches, the axes 0.8-1.3 mm wide
P. convexum
22. Plants perennial.
→ 24
24. Plants cespitose, rhizomes sometimes present but not well-developed; culms 100-200 cm tall, stout; panicle branches ascending, divaricate, or reflexed.
→ 25
25. Leaf blades 7-18 mm wide
P. conspersum
25. Leaf blades 2.5-4 mm wide
P. plicatulum
24. Plants not cespitose, rhizomatous; culms 10-150 cm tall, varying in thickness; panicle branches ascending.
→ 26
26. Rhizomes short, indistinct
P. plicatulum
26. Rhizomes long, evident.
→ 27
27. Plants aquatic; upper florets chestnut brown
P. wrightii
27. Plants not aquatic; upper florets dark brown
P. nicorae
17. Upper florets white, stramineous, or golden brown.
→ 28
28. Lower lemmas with well-developed ribs over the veins; upper glumes absent
P. malacophyllum
28. Lower lemmas not ribbed over the veins; upper glumes present.
→ 29
29. Panicles with 15-100 branches.
→ 30
30. Plants annual; upper glumes and lower lemmas rugose
P. racemosum
30. Plants perennial; upper glumes and lower lemmas smooth.
→ 31
31. Plants rhizomatous, not cespitose; branch axes 0.9-1.2 mm wide; panicle branches often arcuate
P. intermedium
31. Plants cespitose, not rhizomatous; branch axes 0.3-0.6 mm wide; panicle branches straight.
→ 32
32. Panicle branches spreading to reflexed (rarely ascending); leaf blades 10-23 mm wide; axes of panicle branches 0.3-0.4 mm wide
P. coryphaeum
32. Panicle branches erect to ascending; leaf blades 4.9-6.1 mm wide; axes of panicle branches 0.5-0.6 mm wide
P. quadrifarium
29. Panicles with 1-15 branches.
→ 33
33. Spikelet pairs not imbricate; lower glumes usually present
P. bifidum
33. Spikelet pairs imbricate; lower glumes absent or present.
→ 34
34. Spikelets 1.3-2.5 mm long.
→ 35
35. Upper glumes, usually also the lower lemmas, shortly pubescent.
→ 36
36. Lower glumes present
P. langei
36. Lower glumes absent.
→ 37
37. Panicles both terminal and axillary, the axillary panicles partially or completely enclosed by the subtending leaf sheath
P. setaceum
37. Panicles all terminal.
→ 38
38. Leaf blades involute; culms 80-110 cm tall
P. laxum
38. Leaf blades flat; culms 20-75 cm tall.
→ 39
39. Spikelets 1.3-2 mm long, 0.7-1 mm wide, elliptic; upper glumes and lower lemmas 5-veined; culm bases swollen
P. caespitosum
39. Spikelets 2-2.5 mm long, 1.4-1.6 mm wide, ovate; upper glumes and lower lemmas 3-veined; culm bases not swollen
P. virletii
35. Upper glumes and lower lemmas glabrous.
→ 40
40. Panicles both terminal and axillary, the axillary panicles partially or completely enclosed by the subtending leaf sheath
P. setaceum
40. Panicles all terminal.
→ 41
41. Upper panicle branches erect
P. monostachyum
41. Upper panicle branches spreading to ascending.
→ 42
42. Leaf blades mostly involute; plants of sandy or rocky areas, usually on the coast
P. pleostachyum
42. Leaf blades mostly flat; plants of inland areas or, if coastal, then in marshy areas.
→ 43
43. Upper glumes and lower lemmas 3-veined.
→ 44
44. Leaf blades usually conduplicate, 2.2-8.3 mm wide
P. praecox
44. Leaf blades usually flat, 5-10 mm wide
P. virletii
43. Upper glumes and lower lemmas 5-veined.
→ 45
45. Axes of panicle branches 0.2-0.5 mm wide; ligules 0.2-0.4 mm long
P. caespitosum
45. Axes of panicle branches 1.5-2 mm wide; ligules 2.2-4.7 mm long
P. lividum
34. Spikelets 2.5-4.1 mm long.
→ 46
46. Upper glumes, and usually lower lemmas, pubescent.
→ 47
47. Lower glumes present
P. langei
47. Lower glumes absent.
→ 48
48. Leaf blades 2-5 mm wide; upper glumes and lower lemmas abundantly pubescent, most hairs longer than 0.1 mm; spikelets elliptic
P. bartwegianum
48. Leaf blades 4-18 mm wide; upper glumes and lower lemmas glabrous or sparsely pubescent, the hairs shorter than 0.1 mm; spikelets obovate to elliptic
P. pubiflorum
46. Upper glumes, and usually lower lemmas, glabrous.
→ 49
49. Upper florets golden brown.
→ 50
50. Plants not rhizomatous; culms decumbent and rooting at the lower nodes; spikelets 1.3-1.6 mm wide; lower lemmas 5-7-veined; lower glumes often present
P. modestum
50. Plants rhizomatous; culms erect, not rooting at the lower nodes; spikelets 1.9-3.1 mm wide; lower lemmas 3-veined.
→ 51
51. Panicle branches 1-6; upper glumes 5-veined; leaf blades 3-18 mm wide
P. floridanum
51. Panicle branches 1-3; upper glumes 3-veined; leaf blades 3-4 mm wide
P. unispicatum
49. Upper florets stramineous to pale, but not golden brown.
→ 52
52. Terminal panicle branches erect.
→ 53
53. Blades involute; upper glumes 1-veined
P. monostachyum
53. Blades flat; upper glumes 3-veined
P. unispicatum
52. Terminal panicle branches spreading to ascending.
→ 54
54. Spikelets 2.2-2.6 mm long.
→ 55
55. Spikelets 1.2-1.5 mm wide, elliptic to obovate
P. lividum
55. Spikelets 2-2.8 mm wide, orbicular to suborbicular
P. praecox
54. Spikelets 2.6-4.1 mm long.
→ 56
56. Plants decumbent, rooting at the lower nodes, not rhizomatous; spikelets obovate to elliptic
P. pubiflorum
56. Plants rhizomatous, neither decumbent nor rooting at the lower nodes; spikelets orbicular to elliptic.
→ 57
57. Spikelets 2.1-3.1 mm long, 2-2.8 mm wide, orbicular to suborbicular; upper glumes 3-veined; leaf blades conduplicate
P. praecox
57. Spikelets 2.9-4.1 mm long, 1.9-3.1 mm wide, suborbicular to elliptic; upper glumes 5-veined; leaf blades flat
P. floridanum
1. Leaf blades conspicuously basal, recurved, 3-10 mm wide; lower lemmas without evident midveins.
→ 2
2. Leaf blades yellowish-green, usually glabrous; spikelets usually glabrous, not spotted
var. longepedunculatum
2. Leaf blades grayish-green, hirsute; spikelets short pubescent, often spotted
var. villosissimutn
1. Leaf blades more evenly distributed, lax to straight, 1.5-20 mm wide; lower lemmas with or without evident midveins.
→ 3
3. Leaf blades glabrous (or almost so) on the surfaces, sometimes ciliate on the margins.
→ 4
4. Leaf blades 2.4-6.1 mm wide, stiff; spikelets 2-2.6 mm long
var. rigidifolium
4. Leaf blades 3-18 mm wide, lax to somewhat stiff but, if somewhat stiff, more than 6 mm wide; spikelets 1.7-2.4 mm long.
→ 5
5. Lower lemmas without evident midveins; blades yellowish-green to dark green
var. stramineum
5. Lower lemmas with evident midveins; blades dark green to purplish
var. ciliatifolium
3. Leaf blades evidently hirsute on the surfaces as well as on the margins.
→ 6
6. Plants widely spreading to prostrate.
→ 7
7. Leaf blades grayish-green; lower lemmas without evident midveins
var. psammophilum
7. Leaf blades yellowish-green; lower lemmas with or without evident midveins
var. supinum
6. Plants erect to spreading.
→ 8
8. Lower lemmas usually with evident midveins; spikelets 1.8-2.5 mm long, usually glabrous, light green to green
var. muhlenbergii
8. Lower lemmas usually without evident midveins; spikelets 1.4-2.4 mm long, usually pubescent, pale yellow to light green.
→ 9
9. Leaves grayish-green; blades 1.5-7 mm wide, always conspicuously hirsute
var. setaceum
9. Leaves yellowish-green to dark green; blades 3.3-13.5 mm wide, almost glabrous or conspicuously hirsute
var. stramineum
Source FNA vol. 25, p. 566. Treatment author: Charles M. Allen; David W. Hall;. FNA vol. 25. Treatment authors: Charles M. Allen, David W. Hall.
Parent taxa Poaceae > subfam. Panicoideae > tribe Paniceae Poaceae > subfam. Panicoideae > tribe Paniceae > Paspalum
Sibling taxa
P. acuminatum, P. almum, P. bifidum, P. blodgettii, P. boscianum, P. caespitosum, P. conjugatum, P. conspersum, P. convexum, P. coryphaeum, P. dilatatum, P. dissectum, P. distichum, P. fimbriatum, P. floridanum, P. hartwegianum, P. intermedium, P. laeve, P. langei, P. laxum, P. lividum, P. malacophyllum, P. minus, P. modestum, P. monostachyum, P. nicorae, P. notatum, P. paniculatum, P. pleostachyum, P. plicatulum, P. praecox, P. pubiflorum, P. quadrifarium, P. racemosum, P. repens, P. scrobiculatum, P. unispicatum, P. urvillei, P. vaginatum, P. virgatum, P. virletii, P. wrightii
Subordinate taxa
P. acuminatum, P. almum, P. bartwegianum, P. bifidum, P. blodgettii, P. boscianum, P. caespitosum, P. conjugatum, P. conspersum, P. convexum, P. coryphaeum, P. dilatatum, P. dissectum, P. distichum, P. fimbriatum, P. floridanum, P. intermedium, P. laeve, P. langei, P. laxum, P. lividum, P. malacophyllum, P. minus, P. modestum, P. monostachyum, P. nicorae, P. notatum, P. paniculatum, P. pleostachyum, P. plicatulum, P. praecox, P. pubiflorum, P. quadrifarium, P. racemosum, P. repens, P. scrobiculatum, P. setaceum, P. unispicatum, P. urvillei, P. vaginatum, P. virgatum, P. virletii, P. wrightii
P. setaceum var. ciliatifolium, P. setaceum var. longepedunculatum, P. setaceum var. muhlenbergii, P. setaceum var. psammophilum, P. setaceum var. rigidifolium, P. setaceum var. setaceum, P. setaceum var. stramineum, P. setaceum var. supinum, P. setaceum var. villosissimutn
Name authority L. Michx.
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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