GRASS FAMILY. . 



B. Spikelets i -many-flowered; rachilla generally articulated above the two lower *cale<h*l 

 them in Nos. 32, 40, 48 and 54) and frequently extending beyond the flower i^i-n^SSkSetT 



Culms herbaceous. 



Spikelets upon pedicels in panicles, spike-like ,,a,ml, s ,, r raceme., n..t ir, row. 

 Spikelets with but I perfect flower, wliu-1, is u-nninal exe< j,t in ,7 and 

 Empty scales 4 (except m No. 20); pa!-t , , , \. ,..',' 



Empty scales 2; palet 2-nervcd. y j f 



Spikelets with 2 or more perfect flowers (except that ..nc is *t., 

 45) ; upper flower often imperfect. 



shortl ' r lhan tlu ' c! " I>ty luWl ' r ""' " u"y with a brat 





awn on tne back. VJI , 



Flowering scales generally longer than the empty lower on,* unawnedor with'* 



straight awn from the apex. 



Spikelets in two rows, forming a one-sided spike or raceme f\ 01 



Spikelets in two opposite rows, forming an equilateral spike (unilat- 



Culms woody, at least at the base; tall reeds. Xjl 



Tribe I. MAYDEAE. 



Fertile spikelets imbedded in the joints of the thick rachis. I. Tribtacvm 



Tribe II. ANDROPOGONEAE. 



Joints of the rachis not much thickened nor excavated for the reception of the BpikeleU. 

 Spikelets alike, perfect, one sessile, one pedicelled. ' > ianikm 



Spikelets not alike, the sessile perfect, tlie pedicelled staminate, empty or wanting 



Inflorescence composed of spike-like silky racemes. 4. Androbogon. 



Inflorescence paniculate; spikelets silky. 



Pedicelled spikelet wanting (in our species). 5. Ckrytopogon. 



Pedicelled spikelet present and usually staminate. 6. > 



Joints of the rachis greatly thickened and excavated for the reception of the spik' 



Tribe III. ZOYSIEAE. 



Spikelets in a terminal spike; second scale spiny. 7. J\',.> 



Tribe IV. PANICEAE. 



Spikelets without a subtending involucre of bristles or valves. 

 Scales 3. 



Spikelets all alike in close i -sided spikes. 



Spikelets with a swollen ring-like callus at the base. 10. Eriockloa. 



Spikelets without a callus. 8. Pus/mlmn 



Spikelets of two kinds, one borne in loose linear panicles, the other solitary on subterranean 



peduncles and maturing seed. 9. Ampkicai^on. 



Scales 4, rarely 3 by suppression of the lowest one. 



Spikelets in 2's or 3's on one side of a long and slender flat or 3 angled ra< - digi- 



tate or approximate in whorls. 1 1 . "ia. 



Spikelets single, pedicelled, in panicles or raceme-like sessile and paniclcd spike*, first 



scale short, third empty or staminate, fourth fertile. 12. " 



Spikelets subtended by an involucre consisting of: 



i-many persistent bristles; spikelets in dense spikes, deciduous. 



2 spine -bearing valves forming a bur enclosing the spikelets and deciduous with them. 



14. Ctmckmt. 



Tribe V. ORYZEAE. 



Spikelets monoecious; tall aquatic grasses. 



Pistillate spikelets ovate, borne at the base of each branch of the panicle. 



15. 7t':a*t 

 Pistillate spikelets linear, borne on the upper branches of the panicle. 



Spikelets not monoecious; grasses of swamps or wet grounds. 



Tribe VI. PHALARIDK \K. 



Third and fourth scales 



small and empty or rudimentary, not awned; stamens 3. 



emptv, awned upon the back; stamens 2. 



subtending staminate flowers with 3 stamens; fertile flowers with 2 stamens 



- 



Tribe VII. AGROSTIDEAB. 



Flowering scale indurated at maturity, of firmer texture than the empty scales, and cloaeljr enve- 

 loping the grain. 

 Rachilla not prolonged beyond the palet. 



Flowering scale with a three-branched awn; stamens mostly J. 

 Flowering scale with a simple awn. 



Flowering scale narrow; awn persistent. 



Awn tortuous or twisted, stout; callus evident. 



Awn straight, very- slender; callus minute. 

 Flowering scale broad; awn slender, straight, decidu > oWOK. .^ 



Flowering scale awnless. 

 Rachilla with a pedicel-like extension beyond the palet: stamens a. 



