FLOKA OF THE DISTRICT OF COLUMBIA. 67 



falling entire, singly or together with the joints of an articulate rachis or with a 



subtending involucre. 



Glumes indurate; lemma and palea hyaline; spikelets falling with the joints of 



the rachis attached. 



Spikelets unisexual, in racemes, the pistillate below, embedded in the indurate 



thickened axis, the staminate in pairs above on the same axis, falling 



after anthesis I. MAYDEAE. 



Spikelets all perfect, or with a staminate or neuter one pedicellate at each joint of 



the rachis H. ANDROPOGONEAE. 



Glumes membranaceous; fertile lemma and palea indurate; rachis not disjointing 

 (spikelets falling with the inclosing bur in Cenchrus). First glume sometimes 

 wanting, the second glume and sterile lemma simulating a pair of glumes. 



in. PANICEAE. 

 Spikelets 1-many-flowered, if l-flowered no sterile lemma below (2 sterile lemmas 

 below in Phalarideae, 1-4 sterile lemmas below in Uniola) ; rachilla usually articu- 

 late above the glumes, these persistent on the pedicel, or in a few genera articu- 

 late below the glumes; spikelets laterally compressed. 



Glumes obsolete. Spikelets l-flowered IV. ORYZEAE , 



Glumes developed or the first rarely obsolete. 

 Spikelets with a pair of sterile lemmas (reduced to minute scales in Phalans) 

 below the one perfect floret, falling attached to it. Panicles narrow. 



V. PHALARIDEAE. 



Spikelets with no sterile lemmas below the perfect ones (a staminate lower floret 



in Arrhenatherum; 1-4 sterile lemmas below the several perfect florets in 



Uniola persistent with the glumes). 



Inflorescence of solitary, racemose, or digitate spikes or racemes, the spikelets 



sessile or only shortly pedicellate., 



Spikelets borne on one side of the axis only (1-sided arrangement somewhat 



obscure in Gymnopogon and Leptochloa) Vin. CHLORIDEAE. 



Spikelets alternate on opposite sides of the axis X. HORDEAE. 



Infloi-escence of open or contracted panicles. 

 Spikelets 1-flowei-ed, the rachilla sometimes prolonged behind the palea. 



VI. AGROSTIDEAE. 



Spikelets 2-many -flowered . 



Glumes usually exceeding the approximate florets or at least the lower; 

 lemmas awned from the back or from between the teeth of a bifid 

 apex (glumes about equaling the lower floret and usually awnless in 



Sphenopholis) VH. AVENEAE . 



Glumes shorter than the lowermost floret, the florets not closely approxi- 

 mate; lemmas awnless or awned from the apex (apex minutely bifid 

 in Brnmus.) 



Plants herbaceous IX. FESTUCEAE. 



Plants woody XI. BAMBOSEAE. 



Tribe I. MAYDEAE. 



A single genus 1. TRIPSACUM. 



Tribe H. ANDROPOGONEAE. 



Spikelets all alike. Plants robust, tall. 



Inflorescence a large grayish fan-sliaped panicle of slender woolly racemes; rachis 



not disarticulating 2. MISCANTHUS. 



Inflorescence a dense, narrowly ovoid,woolly panicle; rachis disarticulating. 



3. ERIANTHUS. 

 Spikelets of 2 kinds, one sessile and perfect, one pedicellate and staminate or 

 neuter (rudimentary in Sorghastrum) at each joint of the rachis. 

 Spikelets in slender, solitary or digitate racemes, these terminal and lateral. 



ANDRGON. 



