43 6 



BOTANICAL GAZETTE 



[DECEMBER 



FIG. 7. Delhi 

 bog and adjacent 

 topography. Scale 

 1:95,000 (f inch 

 = i mile). 



Acidity tests show that the relative acidity is less than in the case of 

 the cassandra-sphagnum and tamarack societies. The soil tempera- 

 ture also runs somewhat higher as noted elsewhere. 



The First Sister Lake may be said to be dominated by three well- 

 marked bog and two mixed societies in which bog and swamp species 

 are brought into competition. The result can be 

 foretold with considerable certainty. The bog vege- 

 tation will sooner or later be replaced by the 

 swamp species. 



BOG NORTH OF DELHI. 



Two miles north of Delhi occurs an extensive 

 bog which was formerly a mile and a quarter (2 km ) 

 long by a half mile wide (0.8 km ) at its broadest part 

 (fig- ?}- The southwestern third has been cleared 

 and is in part under cultivation. The eastern and 

 northern parts have been somewhat interfered with 

 by the cutting of timber, but areas occur which have 

 been but little disturbed by these influences. Near 

 the eastern margin are two small lakes, the last remnants of the larger 

 lake which must have occupied this territory in early postglacial 

 times. The basin is located in a clay moraine of the Erie ice-lobe, 

 and probably owes its origin to unequal deposition by the glacier. 



The plant societies found about the southeastern lake will give an 

 idea of the whole vegetation (fig. 8). 



Aquatic society. The aquatic vegetation is represented almost 

 wholly by the yellow water-lily, Nymphaea advena. This plant 

 forms a broader zone completely encircling the lake and varying 

 from 5 to 10 feet (1.5-3 m ) m width. Accompanying it occur Bra- 

 senia purpurea, Ceratophyllum demersum, Lemna minor, and 

 Spirodela polyrhiza. 



Typha-cassandra-sphagnum society. On the floating margin of 

 the bog substratum occurs a zone which partially encircles the lake. 

 Near its outer edge Typha latifolia is the characteristic plant, but in 

 certain places it is wanting or extends the full width of the zone. 

 Chamaedaphne calyculata, Sphagnum cymbifolium, S. subsecundum, 

 S. recurvum, Carex filiformis, Eriophorum polystachyon, and Salix 



