'Iiii: (iHAssKs OK Tknnkshkk. 21 



3. Racemes slender solitary, pedicellate spikelets reduced to 

 one or two empty flumes 1. A scopakius. 



3. Racemes stout, 2-5 to<jether, digitate; pedicellate spikelet 



with four flumes, staminate (rarely herma])hrodite or 

 neuter) 2. A. pkuvinciai.is. 



4. The plumose pedicels shorter than the sessile spikelets . . 



3. A. AR(;vR.+ rs, 



4. Pedicels lonj^er than the sessile spikelets 5 



5. Upper leaf-sheaths inflated, imbricate; spathes narrow, close, 



racemes finally exserted on lonj^^ slender peduncles . . 

 4. A. Elliotiii. 



5. Upper sheaths not conspicuously inflated, racemes subses- 



sile within the loose spathes 6 



6. Branches of the culm short, erect, rather distant, forming 



an elongated false panicle 5- A. Virginicis. 



6. Branches longer and more compound, crowded towards the 



summit of the culm and more or less spreading, the gen- 

 eral inflorescence corymbosely-paniculate 



6. A. MACROURLS. 



7. Primary branches of the panicle solitary, pedicellate spike- 



let wanting 7. A. nutans. 



((/) Spikelets light brown, awn four and one-half to ten 

 lines long, the column straight or nearly so. ... 



var. avenaceiis. 



(/>) Spikelets very dark brown, awn twelve to fifteen lines 



long, the column distinctly geniculate, var. LintKBafius. 



7. Primary branches whorled pedicellate, spikelet present and 



usually staminate . . S. A. Sorcihum var. Halepense. 



I. Andropogon scoparius Michx. Little Blue-stem, Mountain- 

 sedge. 



Plate II. Figure (>. 



A rather slender perennial, oneto three feet high, moreor less pan- 

 iculate-branched above, the single racemes terminal on the culm or 

 branches. Culms somewhat compressed below. Leaf-sheaths cari- 

 nate, smooth, scabrous or often pilose; ligule about a line long, trun- 

 cate; leaf-blade two to ten inches long, one to three lines wide, 

 very acute, the mid-vein prominent below. Spathe one to two 

 inches long, narrow and acute, or with a short rudimentary blade, 

 apex of the peduncle smooth or sparingly pilose. Racemes par- 

 tially enclosed within the spathe, or more often exserted, erect in 

 flowering, six- to twelve-jointed, the rachis straight or usually 

 flexuose; joints rather slender, somewhat thickened above, rounded 

 and scabrous on the back, flattened on the anterior face, pilose on 

 the edges from near the middle, the hairs increasing in length to- 

 wards the apex, about one-half the length of the sessile-spikelet. 

 Pedicellate spikelet reduced to a short-awned, narrow glume, 

 which usually encloses a smaller one, rarely a staminate flower. 

 Pedicel a little shorter than the sessile spikelet, flattened and 

 broader above, spreading when dry; pilose along the edges, the 

 hairs increasing in length above. Sessile spikelet narrow, lanceo- 

 late, appressed to the rachis, three to five lines long; first glume 



