¶ Branches of the panicle in 2s, 8s, or often single. (*)
* Flowers not webbed, merely pubescent on the back, (a)
a Annual. Panicle dense with subsessile spikelets.....................
a Perennial. Panicle loose, spikelets long-pedicellate..................
Nos. 2, 3
* Flowers webbed. - Spikelets mostly 2-flowered, 2". Pan. very slender.....
- Spikelets mostly 2-flowered, - many, panicle diffuse.....
Nos. 5, 6
- few (4 to 8). Mountains..
- Spikelets mostly 5-flowered, ovate, short-pedicelled.....
Nos. 8, 9
¶ Branches of the panicle in about 5s, half-whorled. (b)
b Spikelets 2 to 4-flowered. - obtuse, pedicellate, loose ........
- acute, pedicellate, very loose.....................
b Spikelets 3 to 5-flowered, subsessile in rather dense panicles................
Nos. 18, 14
1 P. annua L. Annual Spear Grass. Culms decumbent and rooting at the base, compressed, 3 to 8'; lvs. lance-linear, short, smooth, carinate, on loose, glabrous sheaths; stip. oblong, dentate; panicle spreading, the branches generally solitary, at length horizontal; spikelets ovate-oblong, rather numerous, containing about 5, loose flowers. - A small, abundant, annual grass, Can. and U. S., forming a dense, soft and beautiful turf. May - Sept.
2 P. flexuosa Muhl. Culm erect from a tufted base, 12 to 20'; lvs. 2 to 5' by 1 1/2 to 2 1/2", gradually acute; upper half of the culm naked, bearing a thin, open pan.; branches mostly in pairs, filiform, often flexuous, long (2 to 3'), with the few pedicellate spikelets at the end; fls. 3 or 4, lanceolate, scarious-pointed, pubescent but not webbed at base, the gls. about as long (2 1/4"). - Woods, Va., Ky. to Ga. Spikelets not purplish. Apr. - Jl. (P. autumnalis Muhl.)
β. scariosa. Fls. of the spikelet 4 to 6, narrowly lanceolate, remote, nearly glabrous, with conspicuously scarious (blunt) points. - E. Tenn.
3 P. hexantha. Culm weak and slender, 18 to 24', erect from the decumbent lower joint; lvs. 3 to 5' long, very gradually attenuated, the upper reaching the panicle which is very open, the branches in pairs, long (2 to 4'), bearing the long-pediceled spikelets near the end; spikelets oblong (4"), mostly 6 (5 to 7)-flowered, fls. remote, oblong, villous (not webbed) at base, very obtuse and compressed at the scarious apex. - Found at Atlanta, Ga., in meadows, perhaps a foreigner. Spikelets few but large. Jn.
4 P. dinantha. Culms in dense tufts, very slender, 18' to 2f, from fibrous roots; lvs. narrowly linear, about 3' by 1", soon reflexed, sheaths rather shorter; ligule short, truncate; pan. very slender and few-flowered, branches erect, very few, solitary or 2 together; spikelets 2 or 3 (mostly 2)-flowered; fls. acute, obscurely veined, smooth, except the copious web at base, the acute glumes much shorter. - Fields, Montgomery, Ala. May, Jn.
5 P. brevifolia Muhl. Culm compressed, 1 to 2f; lvs. of the culm about 2, flat, oblong, cuspidate and pungent, lower about 1' long, upper 6", root lvs. long and narrow, all erect, keeled and pungent at the point; ligule truncate, lacerate; sheaths nearly as long as the nodes; pan. loose, branches filiform, in pairs; spikelets ovate, 3 to 4-flowered; fls. rather obtuse, 2 1/4' long, slightly webbed. Penn. (Jackson) to Va. and Ill. Spikelets often tinged with purple. Apr., May. (P. pungens Nutt. P. cuspidata Bart.)
6 P. debilis Torr. Culm erect 18' to 2f; lvs. lance-linear, flat, gradually acute; ligule oblong, acute; pan. loose, few-flowered, some spreading, branches mostly in pairs, flexuous; spikelets ovate, obtuse; 3 (rarely 2)-flowered; fls. very obtuse, \\" long, faintly 3-veined, webbed at base; palea green; glumes ovate, acute. - Rocky woods, Conn, to Ill
7 P. laxa Hœnke. Culm eaespitous, 6 - 8'; lvs. linear, acute, erect; stip. lanceolate; pan. 1 - 2' long, contracted, nodding, branches mostly in pairs, smooth, flexuous; spikelets 2 1/2" long, ovate, 3-flowered; fls. often purple, acute, hairy, somewhat webbed at base; glume lance-ovate, slightly scabrous on the keel; lower palea hairy below, upper rough-edged; anth. violet. - Mountains N. Eng. and N. Y. to Arc. Am.
8 P. alpina L. Culms erect, 6', from fibrous roots; lvs. short, broadly linear, obtuse, lower with short, truncate ligules, upper with oblong, acute ones; pan. equal-sided, erect, ovate or oblong, loose, the branches in. pairs, spreading, with rather large, ovate, short-pediceled, 5 (4 to 9)-flowered spikelets; fls. ovate. - Can. West and high northward. Jn.
9 P. compressa. Blue Grass. Culm decumbent and rooting at base, much compressed, 12 - 18'; lvs. linear, short, bluish green; sheaths rather loose, with a short, obtuse stipule; pan. contracted, 3' by 1 or less, somewhat secund, branches very short, in 2s and 3s; spikelets ovate-oblong, flat, 3 to 7-flowered, subsessile, fls. rather obtuse, webbed. A valuable grass, with sweet and nutritious herbage, propagating itself everywhere (Va., Tenn., northward) in woods, pastures and meadows. May, Jn. (a month later than P. pratensis).
10 P. sylvgstris Gray. Culm erect, compressed, 2 to 3f; lvs. flat, soft, 3 to 6' long, 1 to 2" wide, gradually attenuated; ligules blunt; pan. oblong-pyramidal! thin, branches in 5s or more, flexuous, 1 to 2' long, spikelets (2") pedicellate, broad-ovate, 2 or 3-flowered; fls. oblong, obtuse, copiously webbed. - Rocky woods,
Wis. to Ohio, S. to Miss, and Ala. Upper half of culm naked. Pan. 4 to 6' by 2 to 3'. Apr. (South) to Jn.
11 P. serotina Ehrh. Meadow Redtop. Foul Meadow. Culm erect, weak. 2 to 3f; lvs. narrowly-linear, flat, 10 to 15'; ligules elongated (2 to 3"), lacerate; pan. (6' to 10' or 12' by 2' to 4'), branches in 5s, flexuous, capillary; spikelete all pedicellate (l 1/2 to 2"), 2, 3, rarely 4-flowered; fls. webbed, acute, tawny red at apex, or at length colored throughout. - Wet meadows and woods, common in the N. States and Can. Jn. - Aug. Varies with the spikelets all 2-flowered and colored, on the diffuse, capillary branches (in woods and swamps), or all 3 or more-flowered, branches suberect. - Makes excellent hay.
12 P. nemoralis L. Wood Spear Grass. Culm slender, 2 - 3f; lvs. narrow-linear, pale green, smooth as well as the sheaths; ligules scarcely any; pan. 6 - 10' long, slender, nodding when in fruit, branches capillary, flexuous, in 5s (2s to 5s); fls. very acute; spikelets ovate, about 3-flowered, spreading and at length remote, slightly webbed at base. - A tall thin grass, in wet, open woods, N. Eng. to Wis. and Can. Jn., Jl.