Notes on the Growth of the Stipe of Nereocystis Luetkeans 



Sarah M. Sheldon, 

 University of Washington, Seattle. 



During the summer of 1914, at the Puget Sound Marine Station, the 

 writer attempted accurate measurements of the stipe of Nereocystis 

 luetheana. Frye, in his article on Nereocystis luetheana (Bot. Gazette 42: 

 143-146, 1906) estimated the growth of the whole plant between the 

 middle of March and the first of June to be about ten inches per day. 

 This was early in the season and very possibly growth at that time was 

 much more rapid than in July, when the laminae have been carried to the 

 surface of the water. Frye's deductions were made from results noted 

 by looking down through a glass bottomed bucket. He took the approx- 

 imate length of the stipe of young plants in March and about seventy 

 days later, in June, again estimated the length by general observation. 

 From these observations he judged the average growth to be about ten 

 inches per day. 



The results given in this paper were secured by actual measure- 

 ments of the stipe during the later part of June and all of July. The 

 records showing the region of growth were made in August, since the 

 experiments set up in July for this purpose were lost. The long, smooth 

 stalk of the kelp is difficult to measure, since the holdfast, clinging firmly 

 to the rocks below, keeps a great part of the plant beyond reach. At first 

 an attempt was made to drop a weighted line down to the holdfast and 

 then get the length by holding the plant as nearly perpendicular as pos- 

 sible. Now and then this succeeded, but the wind, waves and tide driv- 

 ing the boat about as well as disturbing the perpendicular position of the 

 plant itself, finally made it evident that this method was of little value. 

 Other individuals would often be found twisted about the plant in question 

 when the second measurements were attempted; this also rendered the 

 us of the weighted cord inaccurate. 



Next the weighted cord was again taken and marked off into foot 

 spaces. This was then attached loosely to the stipe by rings of copper 

 wire clamped around it at intervals of about two feet. For a couple of 

 measurements this worked well, but the wind and tide soon stirred up the 

 kelp bed so thoroughly that the same twining of the stipes about each other 



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