Tall grasses, with usually flat leaf-blades and dense terminal spikes. Spikelets 2-several-flowered (rarely 1-flowered), sessile, usually in pairs, occasionally in 3's or more, in alternate notches of the continuous or jointed rachis, the empty scales forming an apparent involucre.to the cluster. Two lower scales empty, attached obliquely, narrow, acute or awned, entire; flowering scales shorter, rounded on the back, 5-nerved, usually bearing an awn. Palet a little shorter than the scale, 2-keeled. Stamens 3. Styles very short, distinct. Stigmas plumose. Grain sparsely hairy at the summit, adherent to the palet. [Greek, to roll up, referring to the involute palet.]

About 40 species, natives of temperate regions. Type species: Elymus arenarius L.

Empty scales of the same length, equalling or longer than the flowering scales.

Spikelets appressed; spike narrow, slender.

Flowering scales glabrous.

Blades less than 3" wide, rarely exceeding 2"; spikelets 1-3-flowered, the flowering scales

4"-5" long, with an awn as long or a little longer.

1.

E. Macouiiii.

Blades 3"-7" wide; spikelets 3-6-flowered, the flowering scales s"-6" long, with an awn

one and a half to twice as long.

2.

E. glaucus.

Flowering scales appressed-hispid.

3.

E. vulpinus.

Spikelets spreading; spike broad and stout.

Flowering scales muticous, or with awn rarely over a quarter as long as the scale.

Spikelets villous.

4.

E. arenarius.

Spikelets glabrous.

Empty scales subulate.

5.

E. condensatus.

Empty scales broad and flat, indurated at the base.

6.

E. curvatus.

Flowering scale with an awn as long as itself or longer.

Empty scales linear-lanceolate to linear.

Empty scales manifestly indurated, usually curved or bowed at the white base.

Awn rarely exceeding one and a half times the length of the flowering scale; awn of the empty scales usually short.

Flowering scales glabrous or hispidulous.

Spike long-exserted, its own length or more, from the narrow upper sheath.

Plant green; flowering scales glabrous or hispidulous; leaf-blades lax,

commonly exceeding 2" wide; a plant of the interioi

. 7. E. jejunus.

Plant grey green, glaucous; flowering scales papillose; leaf-blades stiff,

2" wide or less; a plant of the brackish marshes.

8.

E. halophuus.

Spike included in the broad, inflated upper sheath.

9.

E. virginicus.

Flowering scales hirsute.

10.

E. hirsutiglumis.

Awn exceeding twice the length of flowering scale; awn of empty scales very long.

Spikelets hirsute.

11.

E. australis.

Spikelets glabrous or hispidulous.

12.

E. glabriftorus.

Empty scales not indurated, not white at the base, straight.

13.

E. canadensis.

Flowering scales hirsute.

Flowering scales glabrous or hispidulous.

14.

E. brachystachys.

Genus 106.

GRASS FAMILY.

Empty scales narrowly subulate.

Spikelets hirsute.

15.

E. striatus.

Spikelets glabrous or hispidulous.

16.

E. arkansanus.

Empty scales variable in length, from a short point to longer than the spikelet, even in the same spike.

17.

E. diversiglumis.