174 



FRESH-WATER BIOLOGY 



2S7 (254) Points of the crown of the oogonium one-celled. 



Subfamily Chareae. 

 Only one genus known in America Chora A. Braun. 



Plants mostly encrusted with lime. Principal axis and leaves more or less completely cov- 

 ered with a layer of cells forming the cortex. Leaves six to twelve in a whorl, each usually 

 with several whorls of leaflets, mostly with stipular outgrowths. Antheridia and oogonia on 

 the upper side of Jeaves. Plants either monoecious or dioecious. 



Fig. 247. 



Ckara fragilis Derv. A, two-thirds natural size portion of figure. 

 of leaf showing cortication. C. Chara coronata Ziz. a. oogonium. 



(After Wille.) B. portion 

 b. autheridium. 



In Europe two other genera have been recognized under the Chareae as fol- 

 lows: 



A. Sporophydia borne on the inferior side of the cell which carries the 

 antheridium. ... Lamprothamnus A. Braun. 



B. Sporophydia occupying the place of a leaflet on the anterior side of the 

 leaf, situated between antheridia Lychnothamnus Leonh. 



Class III. Phaeophyceae 



Color brown; plant coarse and large; or fine, filamentous. 



AH species are attached and have a dark or olive green color. Many are 

 small and resemble the Confervales while others reach an enormous size. 

 Sexual reproduction takes place by antheridia and oogonia in the larger species, 

 and by isogametes and zoospores in the smaller. 



The members of this class, with a very few exceptions, occur in salt-water, 

 and the classification of some fresh-water forms which are often placed in this 

 group is doubtful. 



