KEY. 217 



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

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



Eleusiue ludica, Gsertn. 

 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 

 3-20 spherical heads. Cenchrus tribuloides, L. 



Gr. VIII. 61. 

 W. II. 21. 

 No prickly involucre 606 



606. An arborescent, shrubby grass. Flowers polyga- 

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

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

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



Aruudinaria macrospexma, Ms. 

 Gr. V. 40. 

 W, IV. 46. 

 Grasses not arborescent 607 



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



608 

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

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

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

 !rs, but one, neutral, the one or two lower consisting of empty, 

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

 )ales. Spike bearing the imbricate spikelets on one side in 2 

 '0"ws, solitary and arcuate-curved. 



Cteuium Americanmu, Spreng. 

 Gr. IIL 17. 

 W. V. 62. 



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

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



609 



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

 he terminal spikelet, on a distinct, sometimes very short 

 ledicel. Panicle, or raceme 612 



