90 
GRAMINEAE 
Lemmas somewhat keeled, 
a w n 1 e s s ; spike- 
lets small.3. Poa. 
Lemmas rounded on the back, 
a w n e d ; spikelets 
medium .,. 
2. Festuca. 
Glumes papery; lemmas firm, strongly 
nerved, scarious-margined ; upper 
florets sterile, often reduced to a 
club-shaped rudiment enfolded 
by the broad upper lemmas: 
spikelets tawny or purplish, 
usually not green.11. Melica. 
Glumes as long as the lowest floret, usually as long as the spikelet; 
spikelets large, the glumes over 1 cm. long; lemmas awned 
from the back.—A veneae (Oat Tribe).19. Avena. 
Spikelets 1-flowered—A grostideae (Timothy Tribe). 
Rachilla articulate above the glumes, these persistent after the fall 
of the florets. 
Awns straight or none. 
Glumes not compressed-carinate, not ciliate. 
Panicle dense, spike-like; lemma and palea chartaceous ; 
florets bearing a tuft of hairs at base from the 
callus.20. Ammophila. 
Panicle open or contracted ; lemma and palea not chart¬ 
aceous ; florets without hairs at base or with 
short hairs.21. Agrostis. 
Glumes compressed-carinate, abruptly mucronate, stiffly cili¬ 
ate on the keels; panicle dense, cylindric or ellip¬ 
soid....22. Phleum. 
Awns twisted and bent, several to many times longer than the 
slender fruit.23. Stipa. 
Rachilla articulate below the glumes, the spikelets falling entire; 
panicle contracted or spike-like ; glumes long-awned. 
24. POLYPOGON. 
Spikelets sessile on a usually continuous rachis (short-pedicellate in Leptoch- 
loa; the rachis disarticulating in Hordeum, Sitanion, and a few 
species of allied genera). 
Spikelets on opposite sides of the rachis; spike terminal, single.—Hordeae 
(Barley Tribe). 
Spikelets solitary at each node of the rachis (rarely 2 in species of 
Agropyron but never throughout the spike), 2 to several 
flowered. 
Spikelets placed edgewise to the rachis ; first glume wanting ex¬ 
cept in the terminal spikelet.12. Lolium. 
Spikelets placed flatwise to the rachis; glumes in pairs. 
Plants perennial..13. Agropyron. 
Plants annual. 
Glumes ovate, 3-nerved.14. Triticum. 
Glumes subulate, 1-nerved...15. Secale. 
Spikelets more than one at each node of the rachis. 
Spikelets 3 at each node of the rachis, 1-flowered, the lateral 
pair pediceled, usually reduced to awns. 
16. Hordeum. 
Spikelets 2 at each node of the rachis, alike, 2 to 6-flowered. 
Rachis continuous; glumes broad or narrow, entire. 
17. Elymus. 
Rachis disarticulating at maturity ; glumes subulate, extend¬ 
ing into long awns, these and the awns of the 
lemma making the spike very bristly. 
18. Sitanion. 
