GRAMINEAE (GRASS FAMILY) 



12.5 



S4. A. dichotoina. 

 r^ pikelet x 'ii^. 



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

 — Sterile sandy or gravelly soil, Me. to Mo. and southw. 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-| as 

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

 Mo., and southw. 



2. A. basiramea Engelm. Resembling yl. dtcAo^oma, /ree??/ 

 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, \inequal, 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. 



8. 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, 

 refiexed by a loose spii'al 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 thefioret; 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. 

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



85. A. gracilis. 

 Spikelet x 2. 



5. A. 



culms 3-7 d7n. 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. — 



D17 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-av:ned 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. lona". — Dry sterile soil, N. J. to Neb,, and southw. 

 Fig. 86. 



7. A. tubercul5sa Nutt. Culms branched below. 1.5-5 dm 

 tumid (It the joints; leaves long and involute; panicles rigid, 

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

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

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

 base of the awns of equal length ; awns divergent, subequal, 

 3.5-5 em. long. — Dry sandy soil near the coast, Mass. to Miss. ; 

 Great La^es. Aug.-Oct. (Mex.) Fig. 87, 



high, 

 loose, 

 othei 



8(i. A. oliirantha. 

 Spikelet x %. 



and about the 



