130 Dzii'lU'rs of the Sea and Shore 



waters off those shores, a brown seaweed closely 

 related to Fucus, whose differentiated fronds, closely 

 resembling the structure of higher plants, are often 

 torn from their anchorage and found washed up on the 

 beach. This is Sargassum, of which mention has been 

 made before. Two plants of this genus, S. vidgare and 

 S. montacjnei, both of which measure less than three 

 feet in length, are found as far north as Cape Cod; 

 but a larger species, S. bacciferiim, known as the "gulf- 

 weed," grows off the shores of Florida. This latter 

 seaweed has acquired considerable prominence from 

 the fact that it composes the major portion of that 

 extraordinary floating mass of vegetation circling 

 about in the great sea eddies produced by the Atlantic 

 currents and forming the so-called Sargasso Sea. 

 After being carried far from their place of origin 

 many of these plants continue to grow in this mid- 

 ocean tangle as luxuriantly as on their native shores. 



Many of the brown seaweeds are of economic im- 

 portance. Particularly noteworthy in this respect are 

 the giant laminarians of the Pacific coast commonly 

 called sea wrack or kelp. Kelp is harvested by boats 

 equipped with special machinery for the purpose. 

 These ocean reapers bring in great barge loads of this 

 free-for-the-collecting freight from where it floats in 

 huge fields, and turn it over to industrial organiza- 

 tions which convert it into iodine, potassium chloride, 

 and other by-products. Its high potassium content also 

 allows it to be dried and used in that way as a soil 

 fertilizer. 



The large proportions of the kelps make them easily 

 the fastest growing plants in the vegetable kingdom, 



