5. Branching irregular and sparse, often unilateral; short, 



1-celled curved branches frequent C. oligoclona 



5. Branches pluricellular; filaments straight 6 



6. Branches infrequent, often arising at right angles to the main filament; 

 seldom bearing branches of the second order C. insignis 



6. Branches frequent, repeatedly branched, the branches long and tapering, 

 up to 20 times their diameter in length C crispata 



Cladophora callicoma Kuetzing 1843, p. 267 



Attached, densely branched tufts in flowing water. Filaments 

 stout, 75-125/x in diameter at the base, with the cells mostly cylin- 

 drical, narrowing to cells which are 35-50/x, in diameter and inflated 

 in the upper branches. Cells 6-8 diameters long below, shorter above 

 (2-4 diameters long). Branching both dichotomous and, especially 

 in the secondary branchings, alternate. Ends of the branches bluntly 

 rounded. 



Mich. 



Cladophora crispata (Roth) Kuetzing 1843, p. 264 

 PL 19, Figs. 9-11 



Free floating except when young, foraiing rather delicate thalli 

 of successively branched filaments with long, cylindrical cells, 

 gradually attenuated in the branches to slightly narrowed but 

 rounded apices. Main axis 40-75/i, in diameter; branches 20-35/x in 

 diameter. Cells up to 20 times their diameter in length. Cell walls 

 relatively thin. 



This species should be compared with the attached C glomerata, 

 which occasionally is found free-floating. 



Floating in shallow water of lakes. Mich., Wis. 



Cladophora fracta ( Dillw. ) Kuetzing 1843, p. 263 

 PI. 20, Figs. 1-6 



Floating; forming coarse, light-green masses of irregularly branch- 

 ed filaments, the branches often curving. Cells irregularly swollen 

 or clavate (cylindrical in some of the varieties, however); 60-120/* 

 in diameter in the main axis, 1-3 times their diameter in length; 

 20-40/x in diameter in the ultimate branches, 3-6 times their diameter 

 in length. 



This is an extremely variable species, and there are many 

 described forms and expressions. Although the typical plant is 

 considerably branched, some of the forms have few branches and 

 are confusingly similar to Rhizoclonium spp. 



Mich., Wis. 



[137] 



