170 I'AMl'AClvE. 



b. Spikolots not in pairs; empty glumes none. . . . (c) 



c. Pistillate spikelets all above the stamiuate in the 



panicles, linear, subterete, embryo as long as the 



grain 158 



c. Pistillate spikelets terminal and the staminate at the 



base of each branch of the j)auicle; grain subconi- 



pressed, ovate, embryo much shorter. . . ;]{) 



c. Stamiuate and pistillate spikelets in separate panicles, 



rarely in the same, when the staminate are 



terminal 37 



B. Spikelets in panicles, all perfect, much compi'essed. . . (e) 

 e. Empty glumes two; floral glumes of tun awucd. . . . -tO 

 e. Empty glumes none or minute, floral glume awuless. . 41 



35. (39). HydrochloA Beauv. Agrost. 135, t. 24, f. 4 (1812). 



Spikelets snuill, unisexual, monu'cious, spicate, the staminate 

 terminal, the pistillate axillary. Glumes 2, slightly unequal, mem- 

 branous, concave, awnloss, the lower one a little the larger; palea 

 0. Stamens 6. Styles short, distinct, sublatcral; stigmas elongated, 

 shortly ])lumose. Grain included by the glumes, but not adherent, 

 A slender, branching grass, floating or creeping, with flat and luir- 

 row leaf-blades. The ])eduncle terminal, slender, the staminate 

 spikelets few (3-5), towards the apex, subsessile. 'J'he pistillate 

 spikelets subsessile in the upper axils, few-tlowered, slightly j)ro- 

 truding from the sheath of tiie upper leaf, the stignuis j)i'otrudiiig 

 for some distance beyoud the glumes. Seed flat, oval, with a thin 

 translucent ridge on one side, loose in the Ijrittle pericarp. Only 

 one species, which is found in the southeastern })art of thel'nited 

 States. 



It dilVers from Zizania chiefly in the reduction of the 2- to few- 

 flowered spikes, of which the terminal one is stauiinate aiul pedun- 

 culate, the lower one pistillate and sessile in the axils. 



1 H. Carolinensis Beauv. 1. c. 



An aquatic, 20-00 cm. high; leaf-blades 2-3 cm. long; very 

 seldom bearing good flowers. 



Infrequent. ^I'orth Carolina to Florida, July and August. 



