MANUAL OF THE GRASSES OF THE UNITED STATES 



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1. Agrostis retrofracta Willd. (Fig. 652.) Perennial ; culms tufted, 

 erect or decumbent at base, 20 to 60 cm tall; sheaths smooth; ligule 

 of culm leaves 3 to 5 mm long; blades fiat, scabrous, 1 to 2 mm wide; 

 panicle diffuse, 15 to 30 cm long, the branches in distant whorls, 

 capillary, reflexed at maturity, divided above the middle; glumes 

 acuminate, 3 to 4 mm long; lemma about half as long as the glumes, 

 thin, pubescent, short-bearded on the callus, and bearing about the 

 middle a slender geniculate and twisted awn exserted about the length 

 of the glumes; palea nearly as long as the lemma; rachilla slender, 

 pilose, from half to as long as the lemma. Qi — Introduced in 

 central California (15 miles south of Stockton), Texas (Kent), and 

 Ohio (Painesville) ; common in Hawaiian Islands and Polynesia. 



2. Agrostis spica-venti L. (Fig. 653, A.) Annual; culms branched 

 at base, mostly 40 to 60 cm tall; ligule as much as 6 mm long; blades 



Figure 652.— Agrostis retrofracta. Panicle, X l A; glumes and floret, X 10. (Tracy and Earle 403, Tex.) 



flat, 1 to 3 mm wide; panicle 10 to 20 cm long, usually less than half 

 as broad, the branches capillary, spreading, whorled, naked at base; 

 spikelets 2 to 2.5 mm long; glumes somewhat unequal, the first shorter 

 and narrower; lemma about as long as the second glume, scaberulous, 

 with a slender awn from below the apex, the awn about twice as long 

 as the glumes; palea about as long as the lemma; rachilla less than 0.5 

 mm long, o — Introduced at a few points from Maine to Mary- 

 land; Ohio; Portland, Oreg. (fig. 654); Europe. 



3. Agrostis interrupta L. (Fig. 653, B.) Similar to A. spica-venti; 

 panicle narrower, more condensed, interrupted, the branches or some 

 of them floriferous from the base; awn of lemma about 1 cm long 

 O — Introduced in Missouri (St. Louis), Washington (Spokane), 

 Oregon (Portland), Idaho (Nezperce Forest), and British Columbia 

 (Okanogan); Europe. 



4. Agrostis thurberiana Hitchc. Thureer redtop. (Fig. 655.) 

 Culms slender, in small tufts, erect, 20 to 40 cm tall; leaves somewhat 

 crowded at base, the blades about 2 mm wide; panicle rather narrow, 

 lax, more or less drooping, 5 to 7 cm long; spikelets green, pale, or 

 purple, 2 mm long; lemma nearly as long as the glumes, the palea about 

 two thirds as long; rachilla hairy, 0.3 mm long. 01 — Bogs and 

 moist places, at medium and upper altitudes, Colorado to British 

 Columbia and south in the Sierras to central California (fig. 656). 



