DESCRIPTIONS OF TRIBES AND GENERA. 121 



the north temperate zone, the high mountains of the 

 tropics to the south temperate zone. 



T. pratense Pers. {Avena flavescens L.), " Golden oats" 

 (Fig. 62), has a loose panicle and yellow, shining spike- 

 lets, and is a valuable fodder-grass. T. subspicatum 

 Beauv. is arctic, alpine, and antarctic. Trichceta Beauv. 

 and Acrospelion Bess, are species of this genus. 



159. (159) Ventenata Kolr. Like the preceding, but 

 with the flowering glumes of the lower floret entire and 

 awnless, and the spikelets longer and narrower ; empty 

 glumes 3-5-nerved. 



Species three, Europe (P. avenacea Kolr.) and the 



Orient. 



160. (160) Avena L. Spikelets 2-6-flowered (rarely 

 one-flowered) in panicles. Empty glumes membrana- 

 ceous, unequal ; flowering glumes rounded on the back, 

 5-9-nerved, often two-toothed ; awn dorsal, geniculate, 

 twisted below (sometimes wanting or straight in culti- 

 vated forms). Callus of flowering glumes and the ra- 

 chilla often hairy ; ovary hairy all over or only at the 

 point ; caryopsis fusiform, deeply sulcate. 



Species over fifty, in the temperate zones of the Old 

 and a few in the New World. 



Sec. I. Crithe. Annuals. Spikelets nodding ; empty 

 glumes many-nerved. A. sativa L., cultivated Oat (Fig. 

 63), with the awns of the persistent flowering glumes 

 straight or none, has originated, perhaps, from the 

 wild Oat (A.fatua L.), which has geniculate awns arid 

 deciduous flowering glumes ; or from a similar species 

 of which there are several in Southern Europe and 

 Western Asia. Oats were cultivated in very ancient 

 times in Europe, and extend as far as 69°.5 north lati- 

 tude. It is the principal grain of Norway and Sweden, 

 where it is used partly for mush, and partly for griddle- 

 cakes (" Fladbrode"). Oatmeal is used in the same 

 way in Scotland, Ireland, and on the Shetland and 

 Orkney Islands. In the rest of Europe and in North 

 America the plant is cultivated mainly as food for horses. 

 In China there is a naked oat (see below) which is used 

 in medicine ; in Europe also water-gruel, made with oat- 



