304 MINNESOTA BOTANICAL STUDIES. 



The stipe was .8 cm. long cylindrical below and slightly 

 flattened above where it merged into the lamina. The lamina 

 was .17 cm. long, rather oblong in shape, showing as yet no 

 traces of the bullations which are so characteristic of the older 

 specimens, and the free end of the lamina even in so young a 

 specimen was not perfect, but slightly notched and irregular 

 due no doubt to the action of the waves. 



The largest specimen studied was found growing at Tracyton, 

 in quiet water. Its length was 143 cm. and the greatest width 

 of the lamina was 30 cm. 



The holdfast by means of which the plant attached itself to 

 the rocks on which it grew, consisted of a mass of dichotomously 

 branched hapteres, which had arisen from above the primitive 

 disc. These hapteres were brown in color, being of a lighter 

 shade and of a more delicate texture towards the apex. In this 

 largest specimen the stipe was unusually short, being but 2.5 

 cm. in length. Most of the specimens examined showed larger 

 stipes, as in one whose lamina was 52 cm. long, the stipe had a 

 length of 8 cm. 



The stipe is strong and tough in texture. It retains the 

 characteristic of the earlier stage of being cylindrical at the 

 base and flattened where it merges into the lamina. 



The laminae of different specimens varied considerably in 

 outline, some being almost oblong, others broad ovate and 

 others elliptical. 



The texture varies also, the laminae of some plants being 

 much thicker and firmer than of others. These differences 

 of form and texture are due, no doubt, to differences in the in- 

 tensity of the light, and the strength of the tidal currents. 



The margins are in every case straight but the apex is almost 

 always frayed and split. There is often one long split extend- 

 ing nearly to the base of the lamina, a second one not so deep, 

 and several minor indentations besides. This splitting takes 

 place in a direction parallel to the margin of the lamina and 

 usually near the rows of bullations. 



Although splitting seems to be the rule, yet our largest speci- 

 men showed scarcely a trace of it. This was no doubt due to 

 the fact that it was found growing in quiet water. Its apex 

 however was frayed somewhat by the action of the waves. 



The region of growth is at the point where the stipe joins the 

 lamina, and here, in the younger portion of the lamina, the bul- 



