208 PRACTICAL BOTANY. 



split, extended above the base of the blade into a scarious 

 appendage (Ugule). All the bracts 2-ranked 565 



No grasses, but plants with a perianth of 3 or more 

 sepals, or segments 639 



Aquatic, small annuals. Flowers monoeciously 

 polygamous. Flowers naked, between two bracts (an ap- 

 parent calyx). Stamen solitary in the sterile flower. Ovary 

 of the fertile flower 2-styled. A fertile and a sterile flower 

 sometimes together in an axil. Callitriche (817). 



GRASSES. 



(565-638.) 



56*>. T. Spikelets of a solitary perfect (rarely staminate 

 or pistillate) flower 566 



II. Spikelets, some of them 1-, some 2-flowered, 

 either pistillate, or staminate, at the joints; the pistillate 1- 

 flowered, consisting of 2 glumes, 3 pales and 1 pistil, occu- 

 pying alternately about the lower third of the rhachis, each 

 separate, and deeply sunk into a boat-shaped recess of it ; 

 the staminate, making u^) the 2 upper thirds of the spike, 

 alternately disposed in pairs, every pair slightly imbedded by 

 the base only, each spikelet consisting of 2 glumes, 2 pales 

 (sometimes with a few additional minute ones), and 3 sta- 

 mens with redantliers. Culm 5-8 feet high. Leaves broadly 

 linear. Spikes (6-8 inches long) commonly 2 or 3 at the 

 top of the culm (sometimes a solitary spike). 



Tripsacum dactyloides, L. 

 Gr. YIII. 62. 

 VV. Y. 63. 



III. Spikelets containing 2 or more flowers (when 

 several, rarely only one of them perfect) 603 



^66. Spikelets of 2 pales only, and without glumes (or 

 the latter rarely present, rudimentary, and forming a little 



cup) 567 



Spikelets consisting of 2 glumes, or at least 2 (or 1) 



glume-like scales, and 1, 2, 3, or 4 pales 568 



567. Flowers perfect, flattened laterally, awnless. Glumes 

 none. Stamens 2 or 3. Leersia. 



Gr. I. 1. 

 W. I. 1. 



