157 



Tribe XII.— HORDED. 



Spikelets 1- to many-flowered, usually hermaphrodite, sessile 

 along the common rachis, forming a simple or compound spike; 1 

 glumes awned or awnless. 



A small tribe of 20 genera and about 130 species. It 

 is an important division, however, for it includes rye, 

 barley, and the many varieties of wheat. English and 

 Italian Rye-grasses {Lolium species) are the chief 

 meadow grasses of the tribe. 



KEY TO THE GEXERA OF THE HORDED. 



1. Spikes slender, unilateral; spikelets 1-flowered, empty glume 1, 

 very small and grown to the rachis 126. Nardus 



1. Spikes not unilateral 2 



2. Spikelets solitary at each joint of the rachis .' 3 



2. Spikelets 2 to 3 at each joint of the rachis 8 



3. Spikes very slender; spikelets 1- or 2-flowered 4 



3. Spikes stout; spikelets usually 2- or more-flowered 5 



4. Flowering glume awned 129. Scribneria 



4. Flowering glume awnless 128. Lepturus 



5. Spikelets placed with one edge against the rachis; outer empty 



glume 1 (in the terminal spikelet 2) 127. Lolium 



5. Spikelets placed with their sides against the rachis; empty 



glumes 2 6 



6. Flowering glumes with a distinct callus at the base, falling at 



maturity with the grain, which is adherent to the palea. 



130. Agropyron 



6. Flowering glumes without a distinct callus, persistent; grain 



free 7 



7. Empty glumes subulate, 1-nerved 131. Secale 



7. Empty glumes lanceolate or ovate, 3- to many-nerved. 



132. Triticum 



8. Spikelets 3 at each joint of the articulate rachis, 1-flowered, 



with a bristle-like prolongation of the rachilla behind the 

 palea at least in the central spikelet 133. Hordeum 



8. Spikelets 2 at each joint of the rachis, with 2 or more her- 



maphrodite flowers 9 



9. Empty glumes minute or none 136. Asperella 



9. Empty glumes usually equaling the flowering glumes 10 



10. Axis of the spike continuous, rarely articulated; empty glumes 

 entire 134. Elymus 



10. Axis of the spike articulated and readily breaking up; empty 

 glumes usually 2- to many-parted or cleft 135. Sitanion 



1 Strictly speaking, the spike is simple when the spikelets are 1-flowered, and 

 compound when more than 1-flowered. 



