GRAMINEAE (GRASS FAMILY) 



125 



erect teeth, middle awn 3-6 mm. long, horizontal, coiled at the base in maturity 



-Oct. Fig. 84. 

 panicles looser 



84. A. dichotoiiia. 

 Spikelet x '^i/j- 



^Sterile sandy or gravelly soil. Me. to Mo. and south w. Au^- 



Var. Curtissii Gray. Differs in being less freely branched''- 



glumes unequal, the second 10-12 mm. long, the first l~\ as 



long; lemma 7-10 mm. long, excluding the awns. Va. to 



Mo., and south w. 



2. A. basiramea Engelm. Resembling A. dichotoma, freely 

 branching at the base; culms sparingly branched; leaves aver- 

 aging longer ; panicles looser, the terminal often partly included 

 in the upper sheaths, sinall panicles commonly borne in the 

 basal sheaths; glumes acuminate, unequal, second 12-14 mm. 

 long, the first about f as long ; lemma about 1 cm. long, exclud- 

 ing the awns ; lateral awns 2-7 mm. long, erect or spreading, 

 middle awn 1-2 cm. long. — Dry soil and prairies, 111. to 

 Minn, and Neb. Aug., Sept. 



3. A. ramosissima Engelm. Culms tufted, wiry, repeatedly branching, the 

 branches divergent; leaves mostly setaceous ; panicle loose, few-flowered ; glumes 

 1.5-2.5 cm. long, awned from a bifid apex, unequal, the second equaling the 



lemma (excluding the awns); lemma 2-2.3 cm. long; 

 lateral awns minute, erect, middle awn 2-3 cm. long, 

 reflexed by a loose spiral at base. — T>rY prairies, Ind. 

 and 111, to Tenn. and Mo. Aug., Sept. 



4. A. gracilis Ell. Culms "slender, in small tufts or 

 solitary, branched at the base, simple or sparingly 

 branched above, 1.5-5 cm. high ; sheaths not loose; blades 

 2 mm. or less wide, usually involute in drying ; spikelets 

 mostly in a slender raceme (if a panicle, the branches 

 rarely bearing more than 2 spikelets), rather distant below, 

 often crowded above ; glumes unequal, the second equal- 

 itig the floret; lemma about 6 mm. long, usually mottled; 

 middle awn horizontal, 8-15 mm. long, lateral awns erect, 

 2-6 mm. long. —Sandy soil, N.H. to Mo., and south w. 

 Sept. Fig. 85. 



5. A. intermedia Scribn. & Ball. Similar to the preceding but much larger • 

 culms 3-7 dm. high, more freely branching, often geniculate at base ; leaves 

 6-15 cm. long, rigid, involute ; panicle 2-4 dm. 

 long, slender, branches short, appressed ; 

 glumes attenuate-aristate, subequal or the 

 second longer, 7-9 mm. long, scabrous, slightly 

 shorter than the floret ; lemma scabrous above 

 the middle, sometimes mottled; aicns all 

 spreading, the middle one 18-22 mm. long, 

 lateral ones 14-17 mm. long, all variable. — 

 Dry soil, la. and Kan. to Miss, and Tex. Aug. , Sept. 



6. A. oligantha Michx. Cidms tufted, wiry, branched 

 at base and at all the nodes, 3-6 dm. high ; sheaths loose ; 

 blades long, usually involute ; panicle or raceme few-flowered, 

 the axis often flexuous and spikelets spreading; glumes unequal, 

 long-awned from a bifid apex, exceeding the floret, the second strongly 

 7-nerved ; lemma 17-20 mm. long, scabrous above ; awns nearly equal, 

 divergent, 3.5-7 cm. long. — Dry sterile soil, N. J. to Neb., and south w. 

 Fig. 86. 



7. A. tuberculbsa Nutt. Culms branched below, 1.5-5 dm. high, 

 tumid nt the joints; leaves long and involute; panicles rigid, loose, 

 the branches in pairs, one short and about 2-flowered, the othei 

 elongated and several-flowered ; glumes 2.5 cm. long, including 

 their slender-awned tips; lemma 12-15 mm. long, the twisted 86. A. oligantha 

 base of the awns of equal length; awns divergent, subecjual, Spikeiet x %. 

 ^.5-5 em. long. — Dry sandy soil near the coast, Mass. to Miss. ; and about tb' 

 Great Lakes." Aug.-Oct. (Mex.) Fig. 87. 



85. A. gracilis. 

 Spikeiet x 2. 



