GRAMINEAE (GRASS FAMILY) 



125 



84. A. dichotoma. 

 Spikelet x 2%. 



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

 Sterile sandy or gravelly soil, Me. to Mo. and south w. Aug.-Oct. FIG. 84. 



Var. Curtissii Gray. Differs in being less freely branched ; panicles looser; 

 glumes unequal, the second 10-12 mm. long, the first f-f as 

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

 Mo., and south w. 



2. A. basiramea Engelin. 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, small 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. Dry 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- 

 ing 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 southw. 

 Sept. FIG. 85. 

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



85. A. gracilis. 

 Spikelet x 2. 



6. 



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



5-15 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 ; awns 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. Culms 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 southw. 

 FIG. 86. 



7. A. tubercul&sa Nutt. Culms branched below, 1.5-5 dm. high, 

 tumid at 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, subequal, Spikelet x %. 

 3.5-5 cm. long. Dry sandy soil near the coast, Mass, to Miss. ; and about the 

 Great Lakes. Aug.-Oct. (Mex.) FIG. 87. 



