26 



When there are two upper and two lower nodal cells to each bract, 

 and both sets develop into a cortex, the stem becomes " diplosiiche 

 corticata," when, as in Ch. sejuncta and all the allied sub-species of 

 Ch. gymnopus, there are eight nodal cells, three upper and three 

 lower develop into cortex cells and the two lateral cells remain 

 undeveloped. In this case 

 the leaf is, like the stem, 

 " iriplostiche corticata." 



In a number of species, 

 especially in many Ameri- 

 can species, the lowest in- 

 ternode of the leaf remains 

 naked, while the median in- 

 ternodes are corticated. 

 This is the case in Ch. hy- 

 dropitys and its allied spe- 

 cies, in Ch. sejuncta and 

 the sub-species of Ch. gym- 

 nopus (see Fig. 30). 



In the first growth of a 

 stem from the protonema, 

 in the earliest shoots from 

 perennial stems and in 

 many abnormal growths, 

 portions of the stem and 

 leaves may be naked, in 

 normally corticated spe- 

 cies. F 'S- 32. 



s , 



BRANCHES. From the basilar node of a leaf (stem node) there arise 

 not only cortex cells and stipular cells, but also new shoots, which 

 may be called branches ; these arise always in the axil of the first 

 leaf of the verticil (or, in some Nitellae, two shoots arise from the first 

 and second leaves). The leaf which develops a shoot in its axil 

 develops no cortex system, and the neighboring cortex cells have to 

 close in and fill the gap. So, on the leaf, when a sporangium arises 

 (always in the axil of the first bract), no cortex system develops from 

 that bract upward. 



Many species of Characese are perennial in the sense that new 

 growths arise from nodes of old stems that have retained their vital- 

 ity over winter. This is especially true of Ch. fragilis in the North 

 and Ch. gymnopus Humboldtii in the South. In some cases the 



