GENEKA OF GRASSES OF THE UNITED STATES. 
11 
Key to the genera of Festuceae — Continued. 
26a. Callus of florets bearded ; lemmas erose at the summit 7. Fluminea. 
2Gb. Callus not bearded (lemmas cobwebby at base in Poa) ; lemmas not 
erose (slightly in Puccinellia) 27 
27a. Lemmas keeled on the back (somewhat rounded in Poa scabrella 
and its allies) 28 
28a. Spikelets strongly compressed, crowded in one-sided clusters 
at the ends of the stiff, naked panicle branches 21. Dactylis. 
28b. Spikelets not strongly compressed, not crowded in one-sided 
clusters 29 
29a. Lemmas awned from a minutely bifid apex (awnless or 
nearly so in Bromus unioloides and B. brizaeformis) ; 
spikelets large 2. Bromus. 
29b. Lemmas awnless; spikelets small 8. Poa. 
27b. Lemmas rounded on the back (slightly keeled toward the summit 
in Festuca and Bromus) . 30 
30a. Glumes papery ; lemmas firm, strongly nerved, scarious-mar- 
gined ; upper florets sterile, often reduced to a club-shaped 
rudiment infolded by the broad upper lemmas ; spikelets 
tawny or purplish, usually not green 24. Melica. 
30b. Glumes not papery ; upper florets not unlike the others 31 
31a. Nerves of the lemma parallel, not converging at the sum- 
mit or but slightly so ; lemmas awnless mostly obtuse_ 32 
32a. Nerves prominent ; plants usually rather tall, grow- 
ing in woods or fresh-water marshes 4. Panicularia. 
32b. Nerves faint ; plants low, growing in saline soil. 
6. Puccinellia. 
31b. Nerves of the lemma converging at the summit ; lemmas 
awned or pointed (upper florets only minutely awn- 
tipped in Bromus brizaeformis) 33 
33a. Lemmas entire, awned from the tip or pointed 
(minutely toothed in Festuca elmeri and F. 
gigantea) 3. Festuca. 
33b. Lemmas awned or awn-tipped from a minutely bifid 
apex 2. Bromus. 
Tribe 3, Hordeae. 
Spikelets 1 to several flowered, sessile on opposite sides of a jointed 
or continuous axis forming symmetrical (not one-sided) spikes. 
This small but important tribe, found in the temperate regions of 
both hemispheres, includes our most important cereals, wheat, barley, 
and rye. The rachis is flattened or concave next to the spikelets, or 
in some genera is thickened and hollowed out, the spikelets being 
more or less inclosed in the hollows. In Triticum and its allies there 
is one spikelet at each node of the rachis ; in Hordeum and its allies 
there are two or three at each node. In Lolium and its allies the 
spikelets are placed edgewise to the rachis, and the first or inner 
glume is suppressed except in the terminal spikelet. The rachilla of 
the spikelet disarticulates at maturity in several genera. In some 
species of Elymus and especially in Sitanion the glumes are very 
