
VOLUME XXXI NUMBER 3 
BOTANICAL” GAZETTE 
MARCH, roor 
THE PHYSIOGRAPHIC ECOLOGY OF CHICAGO AND 
VICINITY; A STUDY OF THE ORIGIN, DEVELOP- 
MENT, AND CLASSIFICATION OF PLANT SOCIE- 
TIES, 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 
XXIV. 
HENRY CHANDLER COWLES. 
[Concluded from p. 108.] 
2. THE POND-SWAMP-PRAIRIE SERIES. 
A. The pond.— There are all gradations between rapid streams 
and completely undrained ponds, and corresponding with these 
various gradations are characteristic plant species. It will be 
convenient to subdivide the series under discussion into two 
parts, the first dealing with undrained ponds and swamps, the 
second with half-drained ponds and swamps. 
No two floras can be more unlike in species or in adaptations 
than are the typical brookside and swamp floras. Though each 
type may be called hydrophytic, so far as the water is concerned, 
the vegetation is really hydrophilous in the first case but pro- 
nouncedly xerophilous in the second. Peat bogs which may be 
taken as the type of undrained swamps have a remarkable assem- 
blage of xerophytic adaptations, such as leathery or hairy leaves, 
and special structures for water absorption. Schimper*® believes 
*3SCHIMPER : Pflanzengeographie, p. 18. 
145 
