OLIVE COLORED ALG^E. 79 



It has a cylindrical frond as thick as a sparrow's 

 quill, which forks very near the base, and again each 

 of the parts repeatedly fork more and more remotely, 

 but less and less widely, six or seven times. The fruit 

 is borne in the thickened terminal branchlets. It grows 

 to the height of three or four inches. There are no 

 air vessels. 



FUCUS VESICULOSUS, L. — "ROCKWEED." 



This is the Fucus with little bladders, or air vessels. 

 Of the two Fuci which cover the rocks and wood-work 

 of wharves, along our whole eastern coast, as far south 

 as the Carolinas, the most plentiful is the one named 

 above. This and the next, grow together everywhere. 

 The plants of this species are greatly variable in size 

 according to their place of growth, being most luxuriant 

 where they have the tide longest. The frond varies 

 from a quarter of an inch to one and one-half inches in 

 width, and from two inches to two feet in length. It 

 is tough and leathery in substance, decidedly flat, 

 with an evident midrib throughout the main stem 

 and branches. It branches by forking, and the axils 

 of the divisions are usually very acute. Each frond 

 is commonly provided with from one to several pairs 

 of oval air bladders, immersed in the substance of 

 the frond, each side of the midrib. It bears its seed 



