DESCRIPTIONS OF TRIBES AND GENERA. 87 



c. Spikelets in twos or threes in the axils of sheath- 

 like subtending bracts. 

 a. Only one subtending bract with 2-3 united 



spikelets terminating the culm. . 92. Lygeum. 

 /?. Subtending bracts in two series with 2-3 free 



spikelets in the axil of each. 91. Anomochloa. 



78. (39) Hydrochloa Beauv. An aquatic grass with 

 flat leaves, 3-5 $ spikelets in a terminal spike, a few ? 

 in each axillary spike, which scarcely exceeds its sub- 

 tending sheath. Stigmas long. 



Species one (H. Caroline?isis Beauv.), in the Southern 

 United States. 



79. (26) Pharus L. $ spikelets linear ; empty glumes 

 two, short ; flowering glume long, coriaceous, involute. 

 Palea two-nerved. Spikes paniculate. Leaves broad, 

 pedicellate ; blade reversed. (See page 8.) 



Species five, in tropical America. 



80. (27) Leptaspis Brown. 6 spikelets small, termi- 

 nal on the short branchlets ; $ spikelets 1-2, sessile on 

 the lower portions of same, large, globose, with two short 

 empty glumes. Leaves as in Pharus. 



Species five, in the tropics of the Old World. 



81. (41) Luziola Juss. (Fig. 36). Spikelets awnless, 

 ovate ; flowering glume with many prominent nerves. 

 Caryopsis with a thick, hard peri- 

 carp. Creeping, narrow-leaved, 

 marsh or aquatic grasses. 



Species six, from Brazil to Ala- 

 bama. 



Sec. I. Enluziola. $ and $ spike- 

 lets in separate panicles. Stamens 

 usually more than six (6-18). 



Sec. II. Caryochloa (Trin. as a 

 genus). Arrozia Schrad. $ and ? 



.,...., . , ~. Fig. 36.— Luziola Peruviana 



spikelets in the same panicle, ota- Juss. a $ spikeiet. 

 mens six. 



82. (40) Zizaniopsis Doll & Ascherson. Habit of 

 Zizania. $ spikelets terminating the branches of the 

 panicle. Fruit a globose nut with a hard, shining, easily 



