46 
Lemmas pilose on the nerves....... 31. 
Lemmas not pilose on the nerves. 
Lemmas 1-nerved; pericarp sep- 
arating from the seed... .32. 
Lemmas 3 to 5-nerved; peri- 
carp adherent to the seed. 
Rachilla prolonged behind 
the palea; lemma 
with a short awn on 
the back.......2 22... 36. 
Rachilla not prolonged be- 
hind the palea; lem- 
mas awnless, 
Glumes longer than the 
Tribe VII. AVENEAE. 
Awns attached between the teeth of the lemma, flat- 
Awns dorsal, not flattened. 
Grain adherent to the palea; spikelets mostly 
more than 10 mm, long.................... 39. 
Grain free; spikelets less than 10 mm. long. 
Lemmas erose or shortly 2-lobed at the apex; 
panicles open..........2..2----2-..2- 40. 
Lemmas deeply 2-toothed at the apex, the 
teeth awn-pointed; panicles dense and 
congestéd...........2.022. 002 ee eee eee 41, 
Tribe VI. CHLORIDEAE. 
Spikelets unisexual, dissimilar; flowers moneecious or 
Ci@CIOUS..........eeeee ee ee eee eee ee eee ee eee AZ, 
Spikelets all alike. 
Spikelets with 2 to 4 perfect flowers. 
Spikelets small, numerous, Spproximate; 
glumes thin............- -- 2 AB, 
Spikelets large, few, distant; glumes firm 
and thick............. 
Spikelets with 1, rarely 2, perfect flowers. 
Rachilla jointed below the boat-shaped in- 
flated glumes, the whole spikelet fall- 
ing at maturity........... 
Rachilla jointed above the glumes, these per- 
sistent, not boat-shaped. 
No sterile lemmas present above the 
perfect floret. 
Plants with long stolons; spikelets 
numerous, crowded; spikes 2 
to 6, digitate................ 
. 44, 
.-45, 
-46, 
CONTRIBUTIONS FROM THE NATIONAL HERBARIUM, 
BLEPHARONEURON (p. 74). 
SPOROBOLUS (p. 75). 
CALAMAGROSTIS (p. 79). 
. CALAMOVILFA (p. 80). 
. AcRostIs (p. 78). 
. DantHonra (p. 80). 
AVENA (p. 81). 
Descuampsia (p. 81). 
TRISETUM (p. 82), 
Busius (p. 82). 
LEpTOcHLOA (p. 83). 
ACAMPTOCLADOS (p. 84), 
BECKMANNIA (p. 84). 
CAPRIOLA (p. 84). 
