8 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 
Spikelets in pairs, one sessile and perfect, the other pedicellate and 
usually staminate or neuter (the pedicellate one sometimes 
obsolete, rarely both pedicellate) ; lemmas hyaline. 
13. Andropogoneae (p. 252). 
DESCRIPTIONS OF THE TRIBES AND KEYS TO THE GENERA. ~ 
TRIBE 1, BAMBOSEAE. 
The tribe which includes the bamboos is for the most part confined 
to the Tropics and Subtropics. One genus extends into the southern 
United States. The bamboos have woody jointed, usually hollow 
culms either erect or vinelike. Some of the larger kinds are as much 
as a foot in diameter and 100 feet in height. The common economic 
species of the Tropics, such as Bambos vulgaris Schrad. (Bambos 
bambos (L.) Wight), because of the large hollow culms with hard 
partitions at the nodes found in most large species, can be 
used for a great variety of purposes. Many kinds of bamboos 
are cultivated for ornament in the warmer parts of the United States, 
especially in Florida and California. Arwndinaria japonica Sieb. 
and Zucc. with several-flowered spikelets, and a few species of Phyl- 
lostachys, are hardy as far north as Washington. They form dense 
masses of shoots, usually 8 to 20 feet high. Phyllostachys does not 
usually flower in this country, but the plants can be distinguished by 
the internodes which are flattened on one side. Bambusa is a modi- 
fied spelling of the original Bambos. 
TRIBE 2, FESTUCEAE. 
Spikelets more than 1-flowered, usually several-flowered, in open, 
narrow, or sometimes spikelike panicles; lemmas awnless or awned 
from the tip, rarely from between the teeth of a bifid apex; rachilla 
usually disarticulating above the glumes and between the florets. 
A large and important tribe, mainly inhabitants of the cooler 
regions. The lemma is divided into several awns in Pappophorum 
and its allies, is deeply 2-lobed in Triplasis and in a few species of 
Triodia, 3-lobed in Blepharidachne, several-toothed in Orcuttia, and 
slightly 2-toothed in Bromus and a few other genera, the awn, when 
single, arising from between the teeth. The paleas are persistent 
upon the continuous rachilla in most species of Eragrostis. Sclero- 
pogon, Monanthochloé, Distichlis, and a few species of Poa and 
Eragrostis are dicecious. Gynerium, Cortaderia, Arundo, and Phrag- 
mites are tall reeds. In Blepharidachne there is a pair of sterile 
florets at the base of the single fertile floret, and a rudiment above. 
In some species of Melica there is, above the fertile florets, a club- 
shaped rudiment consisting of one or more sterile lemmas. In Uniola 
there are one to four sterile lemmas below the fertile ones. In Melica 
imperfecta and M. torreyana there may be but one perfect floret. 
