Vol. 44 No. 10 
BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
— 
OCTOBER, 1917 
The structure and development of the plant association* 
Henry ALLAN GLEASON 
Ecological literature has recently been enriched by the pub- 
lication of an exceedingly important book (Clements, 3) on the 
structure and development of vegetation. Not only does the 
book present a thorough and detailed analysis of vegetation, 
based on the researches of the author, but it also reviews the 
theories and summarizes the facts from a vast array of the eco- 
logical literature. For all of its contents the working ecologist is: 
grateful, although it is probable that some of the more radical 
ideas of the author may be accepted reluctantly and that others. 
may be rejected completely. 
Certain features of the monograph can scarcely be reconciled 
with his own by the writer of the present article. Since this 
paper does not pretend to be either a critique or a review, the 
writer will not attempt to discuss his objections in detail, but will 
merely mention what these features are. The chief one of them 
is the view of Clements, first expressed in 1905 (2), that the unit of 
vegetation (irrespective of its scope or of the term used to designate 
it) is an organism. Clements has also so enlarged the-scope of 
the vegetational unit that it includes in his monograph not only 
a climax but also all the successional series leading to the climax. 
Thirdly, as a direct result of these two features, he has portrayed - 
the phenomena of vegetation as exceedingly complex, requiring 
[The BuLLetIN for September (44: 411-462) was issued September 15, 1917-] 
* Contribution No. 165 from the Botanical Department of the University of 
Michigan. 
463 
