PLANTS THAT BUILD ISLANDS 123 



sea-beach panic-grass is very common. In the 

 marshy salt lands we find salt-reed grass, creek- 

 sedge, and numerous other reed-like grasses. The 

 seaside blue-grass is, perhaps, more commonly used 

 than any other kind, especially in the West. This 

 is due to two reasons: because of its sand-binding 

 qualities, and because of its excellence as grazing 

 for cattle. In the South various kinds of sand- 

 binders are used; chief among these are the well- 

 known St. Augustine grass and seaside oats, which 

 use their sand-collecting propensities to save the 

 water-fronts. 



Occasionally an island is formed by a great piece 

 of earth which has broken away from a low-water 

 bank, usually near the mouth of a large river, and 

 floated out to sea, the soil being held firmly together 

 by matted grass roots. The sizes of these floating 

 islands vary from a few feet in diameter to an 

 area of several acres. Sometimes they carry only 

 tiny crawling insects or no life at all ; at other times 

 there are trees and many small animals. Few of the 

 islands exist long after they float out on to the 

 rough waters of the ocean; but one or two have 

 been known to travel many miles, resisting for 

 months and even years all efforts of the waves to 

 buffet them to pieces. 



Some islands rise out of the ocean, perhaps be- 



