HOW TO KNOW THE FRESH-WATER ALGAE 

 284b Thallus otherwise 285 



285a Plant a uniseriate filament, branched or unbranched; (cells in 1 

 series); microscopic 289 



285b Plant a multiseriate filament or thallus; microscopic 



286 



286a Thallus embedded in soft mucilage; consisting of an axial fila- 

 ment with cortical (overlying) cells, bearing whorls of short and 

 usually densely clustered branches; nodes and internodes evi- 

 dent. See Fig. 173 BRATRACHOSPERMUM 



286b Thallus otherwise 287 



287a Thallus consisting of multiaxial filaments (strands of filaments) 

 with numerous feathery branchings; without definite nodes and 

 internodes. Fig. 201 THOREA 



Fig. 201. Thorea ramossisima Bory. 



This is a feathery thallus macroscopically; mi- 

 croscopically composed of a multiaxial cable of 

 filaments with short, compactly arranged out-turned 

 branches. They may be as much as 50 cm. in 

 length. It is of infrequent occurrence and sexual 

 reproductive stages have not been found as yet. 



Figure 201 



287b Thallus otherwise 



288 



125 



