Thk Gkasseh of Tknnksskk. 88 



j^liunes. ICiiipty j^lunies two, unequal, membranaceous, Umj^er 

 that tiie Howering flumes. Flowerinj^ j^lumes rounded on the 

 back, five- to nine nerved, often bidentate or two-toothed at the 

 apex, with a lon^ dorsal twisted awn (the awn may be strai;(ht, or 

 even absent, in cultivated forms). Orain pubescent, at least at the 

 apex, freciuently adhering to the fruiting glume or palea. Annu- 

 als or perennials, with rather large, variously paniculate spikelets. 

 Species about fifty, widely spread over the temperate and cooler 

 regions of the world. There are two or three native North Ameri- 

 can species, and two or three others introduced from Europe exist 

 as weeds in some parts of the country. The genus is best known 

 l)y the common cultivated Oats. 



I. Avena sativa 1.. Oats. 



Plate XXVIT. Figure 110. 



A well-known erect annual, two to four feet high, with flat 

 leaves and expanded panicles of rather large, pendulous and usu- 

 ally two-flowered spikelets. Lower flc^ets sometimes awned. 



Avena satiihi exists in many varieties, whicli have been divided 

 into two classes or races: Panicled oats, with widely-spreading 

 panicle-branches, and Banner oats, with contracted onesided pani- 

 cles. These divisions have been further divided into chaffy and 

 nake'^. fruited varieties. Further varieties are established upon 

 the color or other special character of the grain. 



Avena fatua and A. strigosa, introduced into this country from 

 Europe, are classed as weeds. 



32. ARRHENATHERUM Beauv. Agrost. 55. (1812.) 



Spikelets two-flowered in a loose terminal panicle; the first or 

 lower flower staminate, its glume bearing a twisted and geniculate 

 awn on the back near the base, the upper flower hermaphrodite, 

 its glume short-awned from or near the tip, or awnless; rachilla 

 hairy, articulated above the empty glumes, and extending into a 

 short point or bristle behind the palea of the upper flower. Empty 

 glumes unequal, acute, their sides thin and scarious. Flower- 

 ing glumes firmer in texture than the empty ones, five- to seven- 

 nerved, closely approximate. Palea prominently two-nerved. 

 Stigmas sessile. 



Usually tall perennials, with flat leaves and long narrow pani- 

 cles. 



Species five or six, in the Old World. 



I. Arrhenatherum elatius Beauv. {A.avenaceum^.^.w^'^.) Meadow 

 Oat-grass or Evergreen-grass. 



Plate XXVIII. Figure 109. 



A tall, perennial grass two to four feet high, rather sparingly 

 leafy, with a narrow terminal many- flowered panicle, six to twelve 

 inches long; the branches spreading during flowering. Spikelets 



