PAPERS ON BIOLOGY AND AGRICULTURE 215 



swamp and bog zones may be distinguished clearly within 

 the limits of the same depression. 



The typical succession of communities in swamps in- 

 clude (1) free floating aquatics such as algae and pond- 

 weeds in deep water; (2) aquatics whose roots are in the 

 soil of the bottom but their vegetative parts float on the 

 surface, as the waterlilies; (3) plants which root in the 

 bottom but have a large part of their vegetative parts 

 above water, as bulrushes, cattails and pickerel-weed; 

 (4) plants which grow in water or very wet soil, as 

 sedges; (5) water-loving shrubs, chiefly willows; (6) 

 swamp trees, as the ash and elm; and (7) the plants of 

 the surrounding uplands when the substratum becomes 

 solid and dry. 



The first three stages of the bog succession are the 

 same as those of the swamp, but at the fourth stage the 

 characteristic bog plants begin to appear, usually on a 

 floating mat made up of the roots and rhizomes of sedges 

 and low woody plants with a filling of sphagnum The 

 characteristic shrubs are Chamaedaphne, Andromeda, 

 Vacciniums and the dwarf birch, and the chief bog tree is 

 the tamarack followed by the upland plants as in the case 

 of the swamp. 



By the identification of these stages, the progress of 

 the succession and the consequent maturity of the bog or 

 swamp may be determined. 



CHARACTERISTICS OF HABITATS 



The depressions in which these bogs are found are all 

 similar in general features except in shape, as they vary 

 all the way from small circular bowls or kettles 200 yards 

 in diameter, to large oval or irregular basins half a mile 

 or more in length. The most irregular is the group con- 

 taining four bogs about a mile northwest of Volo, which 

 will be found to be quite similar in general outline to the 

 drained depression which contains the Fox-Pistakee 

 group of lakes. The profiles of the larger depressions 

 are similar also, usually including broad stretches of 

 shallow, gently sloping plains which extend from the sur- 

 rounding uplands to a deep pocket more or less centrally 

 located. These bordering plains are wet and swampy at 



