10 THE HUMAN SIDE OF PLANTS 
the sandy shores and vast marsh lands. There 
are, too, the familiar fresh-water sedges; but the 
most striking examples are to be found in the sand- 
loving grasses near the sea. ‘The marram grass, 
seaside oats, and St. Augustine grass, are examples 
of this type, which walk with their thin, creeping 
roots over the surface of the sands. So rapid is 
their progress and so widely diverse are their 
meanderings, that they form great and very useful 
nets, which hold down the drifting sands. 
Men living along the shores of the sea appreciate 
the value of these walkers as allies in maintaining 
the physiographical outlines of the coast and in 
protecting their cultivated lands from injury by 
drifting sands. As a result, they plant seeds of 
the various binding grasses, knowing well that, 
once started on the sides of a dune, the walkers 
will rapidly cover its surface and bind down as 
permanent and immutable prisoners its migratory 
grains of sand. 
