VIII. STAPFIA CYLINDRICA IN MINNESOTA. 



CHARLES J. BRAND. 



The material on which these observations are based was col- 

 lected by the writer during August, 1901, in the harbor of Grand 

 Marais on the north shore of Lake Superior. It has also been 

 observed at Tobin and Washington harbors on Isle Royale, 

 Michigan. 



At Grand Marais the plant was found growing in the water, 

 attached to the smooth diabasic rock, at a depth varying from 

 six inches to eight feet. It was most abundant in a small arm 

 of the harbor which is enclosed on two sides by a reef and on a 

 third by a dock crib. The situation is one that does not ordi- 

 narily require any particular ability or adaptation for resisting 

 very violent wave action. However, there are times when the 

 plant is compelled to undergo considerable strain. In the event 

 of a strong wind shoreward the seas break over the outer 

 protecting barrier reef and cause a very strong current from 

 the small arm into the harbor proper and also a fairly violent 

 wave action. 



The water in which the collection was made is very fresh and 

 cold, in fact it is the drinking water of the villagers residing 

 about the harbor. 



It seemed at first that the plant was simply a species of Tetra- 

 spora, but a careful examination leaves no doubt but that it be- 

 longs to the genus Stapjia, established by Chodat in 1897. 



In the present form the position of the thallus in its usual con- 

 dition of growth is always upright. The mode of attachment 

 is by means of a distinct holdfast. Just above the holdfast there 

 is a short attenuated area, beyond which the thallus assumes its 

 ordinary diameter. This feature can readily be observed by 

 reference to the figure of the entire plant (PL XVI., Figs. 



i, 2,3\ 



An examination of the thallus with the dissecting microscope 

 or even without a lens, reveals a much wrinkled and folded sur- 



71 



