728 MINNESOTA BOTANICAL STUDIES. 



of corresponding size. The young forms of Pterygophora 

 californica show the characteristic shape and developmental 

 sequence of the Laminariaceae, resembling particularly young 

 plants of Laminaria saccharina. 



Plant " B." This specimen was collected by Mr. K. Yendo 

 and was kindly presented to me by him. It is apparently of about 

 the same age as Ruprecht's youngest plant. The whole plant 

 is 35 cm. in length, of which 10 cm. is holdfast and stipe, 

 and 25 cm. lamina. The lamina is 8 cm. in breadth at its 

 broadest part. The tip is eroded, as usual, and in this particu- 

 lar specimen the margin is imperfect. The stipe is 8 mm. in 

 diameter, 3 cm. below the base of the lamina, and 5 mm. in di- 

 ameter just above the holdfast, where it is circular in cross-sec- 

 tion. It is, however, elliptical in cross section near the base of 

 the lamina, the stipe being flattened in the plane of the lamina. 

 In this specimen the midrib is beginning to differentiate and is 

 well-marked for a distance of 5 cm. above the base of the lam- 

 ina and faintly marked for 10 cm farther towards the tip. 

 Distally it quite disappears. Certain hapteric outgrowths are 

 decidedly long and slender in this plant much more developed 

 than ordinarily. 



In plant " B," less than i cm. below the base of the lamina, 

 are seen two small emergences, opposite each other on the sides 

 of the stipe. These are the growing points destined to produce 

 the first pair of pinnae. 



Plant " C." This is a somewhat older individual in which 

 twelve pinnae have been developed. The whole plant is 45 cm. 

 in length from the holdfast to the eroded tip of the central 

 lamina. From the holdfast to the lowest pinna is 15 cm. In 

 this plant the four lower pinnae are of a deep chocolate brown 

 color and very much eroded and perforated. They present 

 some points of anatomical interest as will be indicated later. 

 The upper pinnae are olive brown in color and the four upper- 

 most have perfect tips, characteristically rounded, giving to the 

 whole young pinna a distinctly spatulate shape. In texture 

 these young pinnae in the fresh plant are quite unlike the sporo- 

 phylls of Alaria with which they have been compared. To the 

 touch they feel not unlike thin sheets of celluloid. The central 

 lamina has a more leathery feel, like Laminaria or Lessonia. 



In this plant the stipe is 8 mm. in diameter, midway between 

 the holdfast and the pinnae. In the region of pinnae it is de- 



