'bulbils' which develop on subterranean rhizoidal branches. Hence 

 it is customary to find members of this group in compact beds or 

 'meadows.' 



The stem has definite nodes and internodes. From the former, 

 short branches of definite growth ( the 'leaves' ) and longer branches 

 of unlimited growth develop. The leaves and secondary branches 

 may arise in whorls or in a dichotomous or trichotomous plan. The 

 chracteristic manner of growth in the Charophyceae is unique 

 among the Chlorophyta. A meristematic apical cell cuts off node 

 and internodal segments and from the former all lateral branches 

 and sex organs are produced. In one genus cortical cells also develop 

 from the node region and extend both anteriorly and posteriorly 

 along the internodal cell. 



o 



Reproduction is heterogamous and the sex organs are relatively 

 complex. There are both monoecious and dioecious species. The 

 oogonia are large, ovoid, or subglobose cells containing a single egg 

 and are inclosed by a definite number of spirally twisted corticating 

 cells which foim a crown, the cornula, at the apex. The oogonia, 

 like the antheridia, are produced at a node of the stem or its leaves. 

 The antheridia are globose and usually smaller than the oogonia 

 but are frequently conspicuous because of their red color when 

 mature ( as is also the oogonium in some species ) . The shell of the 

 antheridium is composed of a definite number of flat, shield-like 

 cells which have radiating lobes, these interlocking with lobes from 

 other cells. The shield cells bear internally a large number of multi- 

 cellular filaments, in each cell of which a swimming antherozoid is 

 produced. The oogonia may be above, below, or side by side with 

 the antheridia, depending upon the genus. 



The reader is referred to Groves and Bullock-Webster (1920), 

 Fritsch (1935), and Smith (1938) for detailed discussions of the 

 morphology of the group and of the many characteristics which are 

 of taxonomic importance. It is a class which requires special 

 terminology and much careful study in dealing with its taxonomy. 



There is 1 order and 1 family, divided into 2 clearly recognizable 

 tribes. 



ORDER CHARALES 



FAMILY CHARACEAE 



In the taxonomy of this family the arrangement of the sex organs, 

 the presence or absence of cortical cells, and the number and 

 arrangement of these, are the major fundamental characteristics 

 upon which differentiations are made. 



[330] 



