■94 Proceedings of the Ohio State Academy of Science. 



Nymphaea, Peltandra and Pontederia to join the society. Poly- 

 gonum emersum grows at a depth of 5^ feet, not much of the 

 lake basin is therefore forbidden ground to this pioneer upbuilder 

 of the land surface. 



V. Islands formed from fragments of other islands. 



This is rather a means of dissemination and multiplication of 

 islands than the forming of new ones. 



Swamp and bog plants have but shallow root systems, the 

 roots extend to a much greater distance laterally than vertically. 

 The roots of even the largest trees on the Cranberry marsh 

 reach a depth of not more than 10-12 inches below the surface. 

 Such plants are but insecurely anchored and when in exposed 

 situations as the margin of the island, are readily torn away in 

 masses by the storm winds, swept before the wind to finally 

 find lodgment in shallower water or against logs and stumps. 

 There are a number of such fragments near the northeastern 

 shore. They are characteristically small areas with relatively 

 large trees and shrubs and with an entire absence of a marginal 

 society of fixed aquatics. One such small island about 50 feet 

 square, near the east shore of the lake so closely resembles the 

 shrub-forest association of Cranberry Island that it seems a 

 fragment of it bodily transported to its present position. I have 

 designated this island Sphagnum bog Island No. 2. With the 

 exception of the absence of Oxycoccus and the presence of 

 another northern bog plant, Rubus hispidus, the flora is identical. 

 The dominant species are Acer rubrum, Rhus vernix and Alnus 

 rugosa. The living maples of which there are 12 fair-sized trees, 

 are none of them more than 6 inches in diameter, one dead 

 maple measures 8 inches in diameter 12 inches from the ground, 

 and one maple stump is 14 inches in diameter. There are also 

 two seedling Quercus palustris. The surface is high enough to 

 be scarcely wet to the foot. Near the eastern end is quite an 

 abundant growth of Rubus hispidus, a characteristic plant of the 

 Tamarack bogs in the northern counties. In the Pymatuming 

 bog on the border between the northeastern part of Ohio and 



