tg1t] DACHNOWSKI—CRANBERRY ISLAND i 
are a clear instance of the fact that the resistance offered by the 
invaders to the toxic conditions of this habitat is, indeed, but 
slightly effective. 
There are several small ponds in the cranberry-sphagnum zone 
in which the dominance of Decodon and Typha as important 
members of the border vegetation is especially to be noted (fig. 5). 
Decodon is particularly well adapted in making an advance out- 
Fic. 6.—The last stage of a larger water area, now occupied by the advancing 
cranberry-sphagnum association. 
ward upon the water by the manner in which the slender mature 
stems, that bend toward the water, curve at the tips. From the 
submerged part roots arise in considerable numbers, buds form, 
and new plants develop. The young plants remain moored to 
the parent plant for a year or two. As soon as the stools are 
built, they become the habitat of a number of plants such as 
Bidens cernua, Polygonum hydropiperoides, Cyperus strigosus, 
Impatiens biflora, Peltandra virginica, and others. These with 
Decodon and Typha seem, however, unable to persist, for dead 
stems of Typha and remains of stools of Decodon may be seen in 
