218 PRACTICAL BOTANY. 



609. Sessile spikelets single 610 



Sessile spikelets 2-4 together (1- to 8-flowered). 

 Glumes nearly side by side, in front of the spikelets, 2 for 

 each of them, forming an involucre. The lower pale awned, 

 or awnless, rigid, or soft. Both glumes often bristle-awned. 



Elymus. 



Gr. V. 45. 



W. IV. 49. 



610. Spikelets (2- or l-flowerqd) sessile in excavations of 

 the rhachis, forming, before flowering, a cylindric spike. 

 Glumes 2, or 1, placed in front of the spikelet. 



(570) Lepturus paniculatus, Nutt. 

 Gr. V. 41. 

 W. IV. 47. 



Spikelets sessile upon the joints, not in cavities. 

 Glumes, at least those of the terminal spikelet, opposite. .611 



611. Spikelets (5- to 9-flowered) placed edgewise on the 

 rhachis, the terminal one with 2 glumes, the rest with 1 only 

 (the second glume being supplied by the rhachis). Flowers 

 awned, or awnless. Lolium. 



Gr. V. 42. 



AV. IV. 50. 



Spikelets (4- to 9-flowered) placed with the side 

 against the rhachis, all 2-glumed, their flowers alternate on 

 the axis of the spikelet. Glumes ovate, or ovate-lanceolate. 

 Lower pale pointed, or awned from the tip. Triticum. 



Gr. V. 43. 



W. V. 51. 



613. (608.) Spikelets (2- to 4-flowered) raised at each 

 joint in pairs or threes (rarely single) on a very short, thick, 

 callous pedicel (callus). Glumes none, or small, awn-like 

 rudiments. Spike upright, loose. 



Gymnostichum Hystrix, Schreb. 

 Gr. V. 46. 

 W. 49. 

 Stalked spikelets single 613 



613. I. Spikelets composed of staminate flowers on one 

 specimen of the species, and of pistillate ones on another. 

 Ovary stalked. Sterile flowers slightly rounded on the back, 



