212 Lake Maxinkuckee, Physical and Biological Survey 



a new growth rapidly in spring. By May 30 slender phyllodia had 

 been developed on the plants in the thoroughfare, and broad float- 

 ing leaves were beginning to show well. It was noticed in flower 

 June 24. 



32. LARGE-LEAVED PONDWEED 



POTAMOGETON AMPLIFOLIUS Tuckerm. 



The large-leaved pondweed is one of the most attractive species 

 in the lake, the large gracefully curved delicate green leaves show- 

 ing up from under water very handsomely. It prefers rich mucky 

 soil and water of moderate depth. It is rarely found in water 

 shallower than about six feet, and is not abundant in water much 

 deeper than twelve -to fourteen feet although it has been dredged 

 up at a depth of twenty-four feet. In shallow water it has oval 

 smooth floating leaves, quite unlike the submersed thin and curved 

 ones, and much like the floating leaves of P. natans, to which it is 

 closely related. In deep water all the leaves are submersed. Good- 

 sized patches are common in the vicinity of the icehouses and in 

 Outlet Bay. It also is found at the Weedpatch and near the Inlet 

 region. One large patch is present off the green boathouse near 

 the Inlet. Chara and some of the smaller species of pondweed such 

 as P. pectinatus, frequently grow intermixed with it. Where it 

 grows very densely, however, it seems often to exclude other 

 species. 



The large-leaved pondweed makes a shady covert where fishes, 

 especially perch and bluegills, like to hide. The young of some 

 species of snail are common on the underside of the leaves. The 

 Bryozoan, Plumatella, often grows quite abundantly on the leaves 

 and perch eat the leaves, apparently for the Plumatella. The blue- 

 gill, which is quite largely a vegetarian, eats abundantly of the 

 tender leaves. 



In the autumn the older leaves grow weak and flabby. They 

 shed from their surface casts of lime with which, during the grow- 

 ing season, the leaves have coated themselves. These casts, much 

 like plaster or cement casts, frequently cover the bottom around 

 the plants in considerable numbers, and perhaps help considerably 

 in the formation of marl. The young leaves of the extreme tip of 

 the plant, and of its branches, remain green and living the winter 

 through. Rootlets are often put out in late autumn just beneath 

 the terminal buds. These buds break off and float about until spring 

 when they find places of attachment. The plants are widely dis- 

 tributed in this manner. 



