HOW TO KNOW THE FRESH-WATER ALGAE 



210a (198) Plant a cluster of short, erect filaments (usually is branched 

 but sometimes appears unbranched when young; some species 

 form attached discs). Fig. 150 COLEOCHAETE 



Fig. 150 a, Coleochaete Nitellaium 

 Jost; b, C. soluta (Breb.) Pringsh.; 

 c, C. orbicularis Pringsh. 

 There are 4 or 5 species of this 

 genus which are commonly found 

 in this country. They are differ- 

 entiated by habit of growth (pros- 

 trate or in cushion-like tufts) and 

 by size of cells. One species, C. 

 Nitellarum Jost, occurs only in the 

 walls of Nitella (Fig. 3) and is 

 nearly always found wherever the 

 host plant occurs. The endophyte 

 shows especially well when Nitel- 

 la is allowed to deteriorate in a 

 Figure 150 laboratory container. The sheathed 



seta which characterizes Coieo- 

 chate arises from a granule (the blepharoplast) within the cell and 

 emerges through a pore in the wall. The disc-like thallus formed by 

 some species of Coleochaete is frequently found on the sides of glass 

 aquaria. In nature they occur on other algae or on submerged stems of 

 cattail, or on submerged glass and crockery. 



210b Plant not in the form of a cushion of erect filaments 211 



211a Thallus a macroscopic expanded sheet, one cell in thickness 

 (usually in salt water, but occasionally found in brackish and 

 fresh water); attached at one end. Fig. 151 MONOSTROMA 



Fig. 151. Monostroma latissimum (Kuetz.) Wittr. 



In salt water this genus includes species which 

 form large thalli many centimeters long and wide, 

 whereas in freshwater the plants are much smaller. 

 Salt water species- are sometimes carried inland 

 and become distributed when oyster shells are 

 thrown into fiesh water habitats. 



Figure 151 



211b Thallus not a large, flat sheet, not so attached. 



212 



97 



