ECOLOGY 55 



ing rhizomes of the sand-grass get a hold on it their 

 power is greater than that of the wind, and by means 

 of the long ramifying roots and the branching rhizomes 

 the sand is held together long enough for other plants 

 to come in and to establish themselves one by one till 

 the surface of the sand is covered. In this way acres 

 of dry land may be accumulated, and its character 

 changed from that of the bare sand of the shore to the 

 dry pasture land of the low heaths. 



The series of different kinds of plants playing " follow 

 my leader " into the fresh water ponds is another good 

 illustration of the power of the unaided plants to change 

 the nature of a given spot. Into the open water of a 

 mere or pond, with its minute flora of microscopic 

 algae, push out the underground rhizomes of the Phrag- 

 mites reed and the Bulrushes. They send up tall shafts 

 with leaves and flowers, and in the autumn these die 

 down, and the half rotting and fibrous remains are 

 tangled together with the roots and rhizomes, and all 

 tends to catch any further fragments or detritus that 

 is drifting in the water. Gradually, by this means, 

 the reeds collect a soil which tends to make the edge 

 of the pond shallower, so that the Bog-Bean and other 

 shallow water plants can come in and help in the work 

 till so much soil is accumulated that the water is quite 

 shallow, and rushes and Queen of the Meadow and King 

 Cups grow on little marshy mounds with water all round 

 them. These close up, and grasses and sedges and Butter- 

 cups grow in between, and the land is almost firm and 

 established enough to be called meadowland. Behind 

 the grassy strip creeps down the forest, and the trees, 

 keeping their distance behind the zone of grass, advance 

 with its advancing edge till in time the opposite shores 

 meet and the forest closes over the space once occupied 



