Paspalum

Plants annual or perennial; cespitose, rhizomatous, or stoloniferous. Culms 3-400 cm, erect, spreading or prostrate, sometimes trailing for 200+ cm. Sheaths open; auricles sometimes present; ligules membranous. 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. 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. Caryopses orbicular to elliptical, plano-convex or flattened, white, yellow, or brown, x = 10, 12.

Distribution

Conn., N.J., N.Y., Wash., Va., Del., D.C, Wis., W.Va., Pacific Islands (Hawaii), Ont., Fla., N.H., Tenn., N.Mex., Tex., La., Ala., Ark., Miss., Okla., Puerto Rico, S.C., Virgin Islands, N.C., Pa., Mass., R.I., Vt., Nev., Colo., Md., Ga., Utah, Calif., Ill., Ind., Iowa, Kans., Ariz., Idaho, Nebr., Oreg., Ohio, Mo., Minn., Mich., Mont., Ky., S.Dak.

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.

Selected References

Banks, D.J. 1966. Taxonomy of Paspalum setaceum (Gramineae). Sida 2:269-284

Pohl, R.W. and G. Davidse. 1994. Paspalum L. Pp. 335-352 in G. Davidse, M. Sousa S., and A.O. Chater (eds.). Flora Mesoamericana, vol. 6: Alismataceae a Cyperaceae. Instituto de Biologia, Universidad Nacional Autonoma de Mexico, Mexico, D.F., Mexico. 543 pp.

COTECOCA (Comision Tecnico Consultiva de Coeficientes de Agostadero). 2000. Las Gramineas de Mexico, vol. 5. Secretaria de Agricultura, Ganaderia y Desarrollo Rural, Mexico, D.F., Mexico. 466 pp.

Lower Taxa

Paspalum acuminatum, Paspalum almum, Paspalum bifidum, Paspalum blodgettii, Paspalum boscianum, Paspalum caespitosum, Paspalum conjugatum, Paspalum conspersum, Paspalum convexum, Paspalum coryphaeum, Paspalum dilatatum, Paspalum dissectum, Paspalum distichum, Paspalum fimbriatum, Paspalum floridanum, Paspalum hartwegianum, Paspalum intermedium, Paspalum laeve, Paspalum langei, Paspalum laxum, Paspalum lividum, Paspalum malacophyllum, Paspalum minus, Paspalum modestum, Paspalum monostachyum, Paspalum nicorae, Paspalum notatum, Paspalum paniculatum, Paspalum pleostachyum, Paspalum plicatulum, Paspalum praecox, Paspalum pubiflorum, Paspalum quadrifarium, Paspalum racemosum, Paspalum repens, Paspalum scrobiculatum, Paspalum setaceum, Paspalum unispicatum, Paspalum urvillei, Paspalum vaginatum, Paspalum virgatum, Paspalum virletii, Paspalum wrightii

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	Paspalum repens
3	Branches 1-6, persistent, terminating in a spikelet.	> 4
4	Upper florets olive to dark brown	Paspalum scrobiculatum
4	Upper florets pale to stramineous.	> 5
5	Axes of panicle branches 0.6-1.3 mm wide	Paspalum 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	Paspalum dissectum
6	Spikelets 3.2-4 mm long; upper lemmas with a few short hairs at the apices	Paspalum 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	Paspalum conjugatum
8	Spikelets 2.4-3.2 mm long; upper glumes sparsely short pubescent on the back	Paspalum 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	Paspalum vaginatum
10	Plants shortly rhizomatous but appearing cespitose; usually in disturbed inland habitats	Paspalum 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	Paspalum notatum
11	Spikelets 1.9-2.3 mm long; leaf blades flat	Paspalum 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	Paspalum blodgettii
13	Panicle branches 18-50; spikelets ovate, diverging from the branch axes	Paspalum 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	Paspalum fimbriatum
15	Upper glumes and lower lemmas pilose.	> 16
16	Panicle branches 2-7; spikelets 2.3-4 mm long	Paspalum dilatatum
16	Panicle branches (4)10-30; spikelets 1.8-2.8 mm long	Paspalum 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	Paspalum 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	Paspalum 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	Paspalum virgatum
21	Axes of panicle branches 0.5-1.2 mm wide; spikelets 1.1-1.8 mm wide	Paspalum 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	Paspalum 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	Paspalum 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	Paspalum conspersum
25	Leaf blades 2.5-4 mm wide	Paspalum plicatulum
24	Plants not cespitose, rhizomatous; culms 10-150 cm tall, varying in thickness; panicle branches ascending.	> 26
26	Rhizomes short, indistinct	Paspalum plicatulum
26	Rhizomes long, evident.	> 27
27	Plants aquatic; upper florets chestnut brown	Paspalum wrightii
27	Plants not aquatic; upper florets dark brown	Paspalum nicorae
17	Upper florets white, stramineous, or golden brown.	> 28
28	Lower lemmas with well-developed ribs over the veins; upper glumes absent	Paspalum 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	Paspalum 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	Paspalum 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	Paspalum 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	Paspalum quadrifarium
29	Panicles with 1-15 branches.	> 33
33	Spikelet pairs not imbricate; lower glumes usually present	Paspalum 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	Paspalum langei
36	Lower glumes absent.	> 37
37	Panicles both terminal and axillary, the axillary panicles partially or completely enclosed by the subtending leaf sheath	Paspalum setaceum
37	Panicles all terminal.	> 38
38	Leaf blades involute; culms 80-110 cm tall	Paspalum 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	Paspalum 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	Paspalum 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	Paspalum setaceum
40	Panicles all terminal.	> 41
41	Upper panicle branches erect	Paspalum monostachyum
41	Upper panicle branches spreading to ascending.	> 42
42	Leaf blades mostly involute; plants of sandy or rocky areas, usually on the coast	Paspalum 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	Paspalum praecox
44	Leaf blades usually flat, 5-10 mm wide	Paspalum 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	Paspalum caespitosum
45	Axes of panicle branches 1.5-2 mm wide; ligules 2.2-4.7 mm long	Paspalum lividum
34	Spikelets 2.5-4.1 mm long.	> 46
46	Upper glumes, and usually lower lemmas, pubescent.	> 47
47	Lower glumes present	Paspalum 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	Paspalum 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	Paspalum 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	Paspalum 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	Paspalum floridanum
51	Panicle branches 1-3; upper glumes 3-veined; leaf blades 3-4 mm wide	Paspalum 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	Paspalum monostachyum
53	Blades flat; upper glumes 3-veined	Paspalum 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	Paspalum lividum
55	Spikelets 2-2.8 mm wide, orbicular to suborbicular	Paspalum praecox
54	Spikelets 2.6-4.1 mm long.	> 56
56	Plants decumbent, rooting at the lower nodes, not rhizomatous; spikelets obovate to elliptic	Paspalum 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	Paspalum 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	Paspalum floridanum