An Ecological Study of Buckeye Lake. 41 



The vegetation of tlie pools shows a marked seasonal varia- 

 tion. The plants sink to the hottom during the cold season and 

 rise to the surface and are most abundant during the warmer 

 months of late summer and early fall. In July, 1910, a small 

 depression, i by 2j/4 feet in diameter and 6 inches deep, on the 

 north side of a clump of Alnus in the open zone contained an 

 abundance of Spirogyra and scarcely anything else. 



II. Fixed submerged aquatics. 



This association is but poorly represented at the island's 

 margin. Close to the shore and often among roots of trees and 

 under dead trunks there is a sparce growth of Ceratophyllum 

 with Potamogeton pusillus and P. pectinatus. 



In the sheltered land-locked coves of tlie south and east 

 side and in the larger pools within the bog, Ceratophyllum 

 demersum forms a dense substratum. It is always underneath a 

 cover of floating aquatics, Lemna trisulca, L. minor, Spirodela 

 polyrhiza, and Wollha columbiana. In some oi the smaller 

 pools in the bog meadow, Uatrachium trichophyllum is associated 

 with Ceratophyllum. In two other small, very shallow pools 

 fully exposed to the light, Ctricularia vulgaris is dominant. 



III. Association of Semi-aquatics. 



Semi-aquatics are plants rooted in the substratum and gen- 

 eralh- with leaves and flower stalks above the water. They 

 may also have floating leaves as Castalia and Xelumbo. The 

 latter, later in the season and especially in shallow water, lifts 

 its leaves and blossoms several feet above the water siu-face. 

 (Fig. 14) Xymphaea, Peltandra and Pontederia always bear 

 their leaves well above the surface. This association grows in 

 water 5^ feet deep in lUickc^e Lake and from this (le])th to 

 emergence on the shore. 



There is but a scanty and fragmentary representation of 

 this association as a marginal one in the immediate vicinity of 

 Cranberrv Island. I-'ormerly Castalia tuljerosa was quite abun 

 dant in the larger lagonns at the east side of the island, but for the 

 past four or Ave years the water level in the lake has always been 



