9 6 



JFLORX. 



lute in drying; spike-like panicles 1.25-4.5 dm. long, strict, or sometimes nodding; 

 outer scales of spikelet awn-pointed, the first longer than the second; third scale 

 from two-thirds to three-quarters as long as the first, middle awn 1.8-2.4 cm - l n ^> 

 horizontal, the lateral awns somewhat shorter, erect or divergent. In dry soil, 

 Mass, to Minn., south to Fla. and Tex. Sept.-Oct. 



12. Aristida lanosaMuhl. WOOLLY ARISTIDA. (I. F. f. 302.) Culms 6-12 

 dm. tall. Leaves 3 dm. long or more, about 4 mm. wide, attenuate into a long, 

 slender point; panicle 3-6 dm. long, strict; outer scales of the spikelet awn-pointed, 

 the first 1-1.4 cm - l n g> exceeding the second; third scale slightly shorter than the 

 second, middle awn 1.6-2.4 cm. long, usually horizontal, the lateral awns about 

 two-thirds as long, erect or divergent. Dry sandy soil, Del. to Fla. west to Tex. 

 Aug.-Sept. (Aristida lanala Poir.) 



13. Aristida divaricata H. & B. SPREADING ARISTIDA. (I. F. f. 3063.) 

 Culms 4.5-9 dm. tall, tufted, erect. Sheaths overlapping, rough ; culm leaves, 

 1.5-3 dm. long, 2-4 mm. wide; the sterile shoots from one-third to one-half as 

 long as the culm, the leaves narrower; panicle comprising one-half of the plant, or 

 more, often included at the base, its branches rigid, at length widely spreading; 

 spikelets, exclusive of the awns, about 1.25 cm. long; empty scales acuminate, 

 usually awn-pointed; flowering scale commonly slightly shorter than the empty 

 ones, firm; the lateral awns shorter than the central, which is 1.2-2 cm. long. Dry 

 sandy soil, Kans. to Ariz, and N. Mex., south to Mex. 



14. Aristida tuberculosa Nutt. SEA-BEACH ARISTIDA. (I. F. f. 307.) Culms 

 1.5-6 dm. tall, dichotomously branched. Leaves 1.25-2.25 dm. long, about 2 mm. 

 wide, smooth beneath, scabrous above; panicle 1.252 dm. long, branches slender, 

 ascending; outer scales of the spikelet about equal, awned, the third scale shorter; 

 awns divergent or reflexed, more or less coiled. Sandy soil, especially on sea- 

 beaches, N. H. to Minn., south to Ga. Also in the interior in 111., Wis., Minn, and 

 Neb. Aug.-Sept. 



15. Aristida desmantha Trin. & Rupr. WESTERN ARISTIDA. (I. F. f. 308.) 

 Culms 3-6 dm. tall, branched. Leaves 1.5-3 dm. long, less than 2 mm. wide, 

 smooth beneath, scabrous above; panicle about 1.5 dm. long, the branches slender, 

 ascending; outer scales of the spikelet about equal, the third one shorter; awns 

 spreading or reflexed, somewhat coiled. In dry soil, Kans. (?), the Ind. Terr, and 

 Tex. Aug.-Sept. 



27. STIPA L. 



Generally tall grasses, the leaves usually convolute, rarely flat, the inflorescence 

 paniculate. Spikelets I -flowered, narrow. Scales 3; the two outer narrow, acute 

 or rarely bearing an awn, the third rigid, convolute, with a hairy callus at the base, 

 and bearing a more or less bent awn, which is spiral at the base, and articulated to the 

 scale. Palet 2-nerved. Stamens 3, rarely fewer. Styles short, distinct. Stigmas 

 plumose. Grain narrow, free, tightly enclosed in the scale. [Greek, in allusion to 

 the tow-like plumes of some species.] A genus of about 100 species, distributed 

 throughout the temperate and tropical zones. Besides the following, some 20 

 others occur in the southern and western parts of N. Am. 



Outer scales of the spikelet 4-12 mm. long : 



Obtuse or blunt-pointed, 4 mm. in length. i. S. Macounii. 



Acute, 8-12 mm. in length. 



Awn less than five times the length of the scale. 2. S. viridula. 



Awn more than seven times the length of the scale. 3. S. avenacea. 



Outer scales of the spikelet 2 cm. long or more. 



Base of panicle usually included in the upper sheath; third scale 8-12 mm. long; 



awn slender, curled. 4. S. comata. 



Panicle exserted from the upper sheath; third scale 1.4-2.4 cm. long, awn bent. 



5. S. spartea. 



I. Stipa Macounii Scribn. MACOUN'S STIPA. (I. F. f. 309.) Culms 

 3-6 dm. tall. Leaves 5-12.5 cm. long, 1-2 mm. wide, flat, becoming involute- 

 setaceous in drying, scabrous; panicle 5 12.5 cm. long, contracted, the branches 2.55 

 cm. long; spikelets borne at the ends of the brandies; third scale pubescent with 

 lone, appressed silky hairs, callus obtuse; awn 8-10 mm. long, contorted. N. B. 

 io the N. W. Terr., Me., N. II., Lake Superior, and Mont. July. \S. Richardsoni 

 A. Gray.] . 



