MANUAL OF THE GRASSES OF THE UNITED STATES 



297 



panicle 10 to 25 cm. long, condensed, 

 many-flowered, the branches ap- 

 pressed to subflexuous-ascending, pur- 

 plish to brownish; spikelets 6 to 8 

 mm. long; glumes and lemmas sca- 

 berulous, the glumes about equaling 



Figure 402. — Descham-psia holciformis. Panicle, X 1 ; 

 glumes and floret, X 10. (Bolander, Calif.) 



specimens from Germany and are 

 probably introduced. 



7. Deschampsia holciformis Presl. 

 (Fig. 402.) Culms in dense tufts with 

 numerous basal leaves, erect, rela- 

 tively robust, 50 to 125 cm. tall; 

 blades mostly folded, 20 to 50 cm. 

 long, 2 to 4 mm. wide, rather firm; 



Figure 403. — Aira praecox. Panicle, X 1 ; glumes and 

 floret, X 10. (Amer. Gr. Natl. Herb. 375, Del.) 



the spikelets or shorter, 3-nerved, the 

 lateral nerves of the first often ob- 

 scure; lemmas awned from below the 

 middle, the awns erect, exceeding the 

 spikelet, the callus hairs short. % 

 — Marshes and sandy soil near the 

 coast, Vancouver Island to central 

 California. 



59. AIRA L. 



(Aspris Adans.) 



Spikelets 2-flowered, disarticulating above the glumes, the rachilla not 

 prolonged; glumes boat-shaped, about equal, 1-nerved or obscurely 3-nerved, 

 acute, membranaceous or subscarious; lemmas firm, rounded on the back, 

 tapering into 2 slender teeth, bearing on the back below the middle a slender 

 geniculate, twisted, usually exserted, awn, this sometimes wanting in the 

 lower floret or reduced; callus minutely bearded. Delicate annuals with lax, 

 subfiliform blades and open or contracted panicles of small spikelets. Type 

 species, Aira praecox. Aira, an old Greek name for a weed, probably darnel. 

 Weedy grasses of no economic importance, introduced from Europe. 



Panicle dense, spikelike 1. A. praecox. 



Panicle open. 



Lower floret with awn as long as that of the upper floret 2. A. caryophyllea. 



Lower floret awnless or nearly so 3. A. elegans. 



1. Aira praecox L. (Fig. 403.) ally erect; panicle narrow, dense, 1 to 

 Culms tufted, 10 to 20 cm. tall, usu- 3 cm. long; spikelets yellowish, shin- 



