FIELD BOOK OF PONDS AND STREAMS 



fly to some other place as their own pond dries away. Frogs 

 lay their eggs by thousands in these short-lived ponds and 

 the early summer droughts turn such places into tadpole 

 cemeteries. 



Permanent ponds are the ones w^hich hold the greatest 

 variety of water life. They may be big or little, spring-fed 

 or stream-fed, low in the marsh or high on the upland, in 

 the woods or the open; if they only offer water the year 

 round they can support a large population. 



Life in ponds (Fig. 17). — In nearly all ponds certain plants 

 grow in more or less clearly defined zones and particular 

 communities of animals are associated with them. 



Fig. 1 7. — Diagram of the distribution of pond plants. 

 In the background are the emergent water plants — 

 I, pickerel weed; 2, cat-tails; 3, bulrush; 4, bm-reed; 5, 

 water plantain; 6, arrowhead. In the foreground 

 are the floating-leaved plants — 7, Polygonum; 8, lily 

 pads; 9, spatter-docks; 10, hornwort; 11, eelgrass; 12, 

 pond weed; and the submerged plants — 13, Riccia; 14, 

 bladderwort; 15, water milfoil. 



Closest to shore are the emergent water plants, those which 

 grow with their roots in the water and their stems and leaves 



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