POACEAE. 



29 



2. Avena sativa L. OATS. 

 (Fig. 41.) Annual, glabrous; culms 

 erect, li-5 tall. Sheaths smooth; 

 leaf-blades 1 long or less, 4"-6" 

 wide; panicle 4'-9' long, its branches 

 ascending; spikelets erect, spread- 

 ing or drooping, the outer, empty 

 scales about 10" long, the flowering 

 scales glabrous, awnless, or with a 

 filiform straight awn sometimes a 

 little twisted at the base. 



Occasional on roadsides and in 

 waste grounds, not persisting. Prob- 

 ably always from grain imported for 

 fodder. Native of Europe and Asia. 

 Widely cultivated in temperate regions. 



17. AEUNDO L. 

 Tall perennial grasses, with thick 

 stout somewhat woody culms, broad 

 flat leaves and dense panicles. Spike- 

 lets 2-many-flowered, the rachilla- 

 internodes glabrous. Scales 4-many; empty scales narrow; flowering scales 

 broader, 3-nerved, hairy on the back. Stamens 3. Styles distinct; stigmas 

 plumose. [Name said to be derived from the Celtic for water.] About 6 

 species, natives of the Old World, the following typical. 



1. Arundo Donax L. COW-CANE. (Fig. 

 42.) Culms stout, erect, 9-25 tall. 

 Leaves often 2 long or more and 2'-3' 

 wide; panicle !J-3 long, oblong; spikelets 

 numerous, crowded. 



Persistent after planting, and occasional 

 in marshes and waste grounds. Introduced. 

 Native of the Mediterranean region. Flowers 

 in summer and autumn. Very conspicuous by 

 its large size and large inflorescence. The 

 variegated-leaved race is commonly planted 

 for ornament. 



18. KOELERIA Pers. 



Annual or perennial tufted grasses, 

 with narrow flat or involute leaf-blades 

 and usually dense spike-like cylindrie 

 panicles. Spikelets numerous, crowded, 

 2-5-flowered, the flowers perfect or the 

 upper ones staminate. Scales 4-7, mem- 

 branous, the 2 lower empty, narrow, unequal, the flowering scales similar 

 to the second, sometimes mucronate or short-awned at or just below the apex, 

 the upper scales gradually smaller, the upper 1 or 2 often empty; palet 



