10 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 
Key to the genera of Fcstuceae — Continued. 
14a. Lemmas cleft either side of the midnerve to near the 
base, the lower two sterile, the third floret fertile, the 
fourth reduced to a 3-awned rudiment- 28. Blephabidachne. 
14b. Lemma 2-lobed but not deeply cleft, all fertile but the 
uppermost 26. Teiodia. 
12b. Inflorescence an exserted open or spikelike panicle 15 
15a. Lemmas pubescent on the nerves or callus (except in Tri- 
odia albescens), the midnerve usually exserted as an awn 
or mucro 16 
16a. Nerves glabrous ; callus densely hairy ; lemmas firm ; 
panicle large, diffuse 15. Bedfieldia. 
16b. Nerves hairy at least below, the lateral ones often 
conspicuously so 17 
17a. Palea long-ciliate on the upper half 27. Triplasis. 
17b. Palea sometimes villous but not long-ciliate on the 
upper half; perennials 26. Triodia. 
15b. Lemmas not pubescent on the nerves nor callus (the inter- 
nerves sometimes pubescent), awnless 18 
18a. Glumes longer than the lemmas ; lateral nerves of lemma 
marginal, the internerves pubescent 14. Dissanthelium. 
18b. Glumes shorter than the lemmas ; lateral nerves not 
marginal, the internerves glabrous 19 
19a. Lemmas chartaceous; grain large and beaked, at 
maturity forcing the lemma and palea open_ 13. Diarixa. 
19b. Lemmas membranaceous ; if firm, the grain neither 
large nor beaked 20 
20a. Spikelets subterete; palea longer than the 
lemma, bowed out below 12. Moltnia. 
20b. Spikelets compressed ; palea not longer than the 
lemma, not bowed out below 21 
21a. Lemmas truncate ; spikelets 2-flowered. 
11. Catabrosa. 
21b. Lemmas acute or acuminate ; spikelets 3 
to many flowered ; rachilla continuous, 
the paleas usually persistent after the 
fall of the lemmas 10. Eragrostis. 
lib. Lemmas 5 to many nerved, the nerves sometimes obscure 22 
22a. Spikelets with 1 to 4 empty lemmas below the fertile florets; 
nerves obscure ; lemmas firm 18. Uniola. 
22b. Spikelets with no empty lemmas below the fertile florets ; nerves 
usually prominent ; lemmas membranaceous (firm in a few 
species of Bromus and Festuca) 23 
23a. Lemmas flabellate; glumes wanting; inflorescence dense, 
cylindric ; low annual 25. Axthochloa. 
23b. Lemmas not flabellate ; glumes present ; inflorescence not 
cylindric 24 
24a. Palea winged on the lower half of the keels ; spikelets 
linear, in a loose raceme 5. Plettropogon. 
24b. Palea not winged on the lower half of the keels; in- 
florescence mostly paniculate 25 
25a. Lemmas as broad as long, the margins outspread; 
florets closely imbricate, horizontally spreading- 9. Briza. 
25b. Lemmas longer than broad, the margins clasping 
the palea ; florets not horizontally spreading 26 
