CHAPTER XXIV 

 Tribe XII. HORDE.E 



A SMALL tribe of about 25 genera in the temperate 

 regions of both hemispheres. Spikelets 1- to several- 

 flowered, sessile in spikes. The rachis is flattened or 

 concave next to the spikelets, or in some genera it is 

 hollowed out so that the spikelets are embedded or in- 

 closed. The spike is 1-sided in Nardus (of Eurasia), but 

 symmetrical in all other genera. In Triticum and its 

 allies there is 1 spikelet at each node of the rachis, and in 

 Hordeum and its allies there are 2 or more. The spikelets 

 are usually placed sidewise to the rachis but in Lolium 

 and its allies they are placed edgewise. In these genera the 

 outer glume is fully developed, but the inner (second) 

 glume is reduced or wanting except in the terminal spikelet, 

 where the glumes are equal. The rachis of the spike dis- 

 articulates in Sitanion, Scribneria, Lepturus and a few 

 species of Elymus and Agropyron. In some species of 

 Elymus the glumes, except in the terminal spikelet, stand 

 in front of the spikelet instead of at the 2 sides. According 

 to some these 2 organs are the 2 portions of a single deeply 

 cleft glume (Par. 153) or represent branchlets. In some 

 species of Elymus and especially in Sitanion the glumes 

 are very slender, extending into long awns. In Sitanion 

 the glumes are commonly split into 2-several slender awns. 

 The blades of this tribe usually bear on each side at the 

 base an appendage or auricle. To this tribe belong our 

 most important cereals. 



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