ANNALS 



OF THE 



NEW YORK ACADEMY OF SCIENCES, 



VOLUME X. 



I. — The Nature and Origin of Stipules. 



BY A. A. XYLEE, A.M. 

 Read Feb. 8, 1897. 



The investigation which has resulted in the preparation of this 

 dissertation was undertaken with a view to determine the true 

 nature and phylogenetic origin of those appendages of the bases 

 of the petioles of leaves which are known as stipules and which 

 are present in so large a number of the families of flowering plants. 



The data have been collected from every available source ; the 

 evidences to be gathered from known geological facts have been 

 taken into consideration, observations have been made upon the 

 morphology and anatomy of the foliar organs in a large number 

 of cases, and the gradual modification of leaf-forms in the annual 

 growth of plants from simple scales to adult leaves has been care- 

 fully studied. In addition to the data so gathered, the literature 

 dealing with the subject, relatively scanty though it is, has yielded 

 much valuable material both by the record given of the observa- 

 tions of others and hy the suggestion of lines of investigation. 



With all this material in hand, I have endeavored to ground the 

 theoretical consideration of the problem upon the broadest founda- 

 tion possible in the present stage of the progress of science, and 

 from a comparative study of the evidence gathered from all the 

 various sources of information, have drawn the conclusions set 

 forth at the close of my paper. 



Annals N. Y. Acad. Sci., X, April, 1897.— 1. 



