KEY. 217 



Lower pale ovate, pointless. Spikelets 5- to 7-flowerecl, with 

 a terminal rudiment of a flower. Spikes usually 2-4. 



Eleusiue ludicaj Gaertn. 



Gr. III. 22. 



W. V. 58. 



605. Spikelets (awnless, 2-4 together) in a globular, bur- 

 like involucre, beset with numerous, retrorsely hispid spines. 

 Glumes 2, 2-flowered, the outer one smaller. Lower flower 

 sterile. Involucres sessile ,in a terminal spike, composed of 

 8-20 spherical lieads. Cenchrus tribuloides, L. 



Gr. yill. 61. 

 W. II. 21. 

 No prickly involucre 606 



606. An arborescent, shrubby grass. Flowers polyga- 

 mous (perfect and staminate). Glumes very small, membra- 

 naceous, the upper one largest. Lower pale convex, mucro- 

 nate, or bristle-pointed. Panicle simple, with few spikelets. 



Arundinaria macrosperma, Mx. 

 Gr. Y. 40. 

 AV. IV. 46. 

 Grasses not arborescent 607 



607. Glumes awnless, or sometimes both bristle-awned. 



608 

 Upper glume with a stout, recurved, horn-like awn 

 from the middle of the back, and warty-glandular outside ; 

 lower one much smaller. Spikelets 4- to 6-flowered, all flow- 

 ers, but one, neutral, the one or two lower consisting of empty, 

 awned pales, the one or two uppermost of empty, awnless 

 pales. Spike bearing the imbricate spikelets on one side in 2 

 rows, solitary and arcuate-curved. 



Otenium Americanum, Sprenor. 

 Gr. in. 17. 

 W. V. 62. 



608. Spikelets sessile, single, in pairs, threes or fours, 

 upon the joints of the rhachis, forming a 2- or 4-rowed spike. 



609 



Spikelets (single, or 2 to 3 together) raised, at least 



the terminal spikelet, on a distinct, sometimes very short 



pedicel. Panicle, or raceme 612 



