20 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 
; Key to the genera of Paniceae—Continued. 
12a. Spikelets in slender racemes more or less digitate at the 
Summit Kot the vem lisa eae as a a ea 110. SYNTHERISMA. 
12b) Spikelets: in’ panicles ue Bo Oe De ee 13 
13a. Fruiting lemma boat shaped; panicles narrow. 
108. ANTHAENANTIA. 
13b. Fruiting lemmas convex; panicles diffuse__ 111. Lepronoma. 
1Ob) Bruit -chartaceous-induratey rigid ae eee eee eee 14 
14a. Spikelets placed with the back of the fruit turned away from 
the rachis of the racemes, usually single (not in pairs)______ 15 
15a. First glume and the rachilla.joint forming a swollen ring- 
like callus below the spikelet_________________ 113. HRIocH1Loa. 
15b. First glume present or wanting, not forming a ringlike 
callus below, the:spikelet2222 22232 es) eae 16 
16a. First glume present ; racemes racemose along the main 
AKL Sas Aa LNG ica RN ead 2 Vs Nt 114. BracHrartia. 
16b. First glume wanting; racemes digitate or subdigitate. 
115. AXONOPUS. 
14b. Spikelets placed with the back of the fruit turned toward the 
rachis of the spikelike racemes, or pedicellate in panicles____ 17 
17a. Fruit long-acuminate; both glumes wanting_ 116. RermarocHLoa. 
17b. Fruit not long-acuminate, at least one glume present______ 18 
18a. First glume typically wanting; spikelets plano-convex, 
subsessile in spikelike racemes____----____ 117. PASPALUM. 
18b. First glume present; spikelets usually in panicles______ 19 
19a. Second glume inflated-saccate, this and the sterile 
lemma much exceeding the stipitate fruit. 
120. SACCIOLEPIS. 
19b. Second glume not inflated-saccate______ ‘oe ee 20 
20a. Culms woody and bamboolike; fruit with a 
tuft of down at the apex__________ 119. LASIACIS. 
20b. Culms herbaceous; no tuft of down at the apex 
OE Ee LU ES 118. Panicum. 
TRIBE 138, ANDROPOGONEAE. 
Spikelets in pairs along a rachis, the usual arrangement being 
one of the pair sessile and fertile, the other pedicellate and staminate 
or neuter, or rarely wanting, only the pedicel present; fertile spike- 
let consisting of one perfect terminal floret and, below this, a stami- 
nate or neuter floret, the lemmas thin or hyaline, and two awnless 
glumes, one or usually both firm or indurate. 
A large tribe, confined mostly to warm regions. The rachis is 
usually jointed, disarticulating at maturity, with the spikelets at- 
tached. In a few genera it is thickened. Sometimes the racemes are 
shortened to 1 or 2 joints and borne on branches, the whole forming a 
panicle (as in Holcus and Sorghastrum) instead of a series of 
racemes. In a few genera the spikelets of the pair are alike. In 
Trachypogon the fertile spikelet is pedicellate and the sterile one 
nearly sessile. 
