7. Filaments slender and graceful, less than 10," in diameter ..._ S. tenue 



7. Filaments stouter, 14-18ya in diameter 8 



8. Main filaments 14-17^ in diameter; branches mostly short-pointed; 



cells of the main axis swollen, 1-2 times the diameter in length.__.S. lubricum 

 8. Main filaments (12)-14-18/u in diameter; cells 4-8 times their 

 diameter in length, cylindrical; branches 

 attenuate and setiferous S. flagelliferum 



Stigeoclonium attenuatum (Hazen) Collins 1909, p. 301 



PI. 13, Fig. 1 

 Filaments elongate with upper branching mostly alternate, but 

 dichotomously branched below; the branches either short and spine- 

 like or long and tapering, terminating in a sharply pointed cell or 

 series of cells forming a hyaline seta. Cells cylindrical, with little or 

 no constriction at the cross walls; diameter of cells in the main axis 

 5-7jLi, length 12-20/a. Prostrate portion of thallus little-developed. 

 In bogs, attached to submerged aquatics. Mich., Wis. 



Stigeoclonium fiagelliferum Kuetzing 1845, p. 198 

 PL 11, Figs. 1, 2 



Filaments elongate; some branches dichotomous but mostly op- 

 posite, the branches arising from node-like zones, where a series of 

 2 or more swollen cells in the main axis develops pairs of branches; 

 branches long and tapering to form slender, hyaline setae. Cells 

 mostly cylindrical, but occasional cells barrel-shaped, 12-16- ( 18 )jli 

 in diameter, 30-48;u, long. The basal portion of the thallus (in our 

 specimens ) only slightly developed. 



Attached to wood in flowing water; in Sphagnum bogs. Mich., 

 Wis. 



Stigeoclonium lubricum ( Dillw. ) Kuetzing 1845, p. 198 



PI. 10, Figs. 1, 2 



Filaments elongate and robust; the branches mostly opposite or 

 whorled, developed from barrel-shaped axial cells; secondary 

 branches often forming fascicles near the tips of the filaments, in 

 which the cells are much smaller than in the main axis; branches 

 ending in a blunt point or a hyaline seta. Cells in the main filament 

 up to llfi. in diameter, 12-30ju, long; branch cells 6-7/a in diameter. 

 Prostrate portion of thallus well developed. 



This is the most commonly observed species of Stigeoclonium in 

 our region. It forms conspicuous tufts or extensive expansions on 

 submerged wood, especially in running water. A favorite habitat is 

 the sides of a wooden watering trough. 



Forming bright green, thready tufts in several lakes; common. 

 Mich., Wis. 



[115] 



