PITCHER-LEAVED ASH TREES 



The above photograph shows a leaf of an ash tree (Fraxiniis americana), grown from seeds 

 of a similar tree found in 1904 near the Station for Experimental Evolution, Cold Spring 

 Harbor, Long Island. It will be noted that several of the leaflets form little conical cups. 

 Such leaves are known as ascidia or, popularly, "pitchers." 



As stated in Science, May 18, 1917, trees of this type were supposed to grow only at Cold 

 Spring Harbor, until their discovery last summer at two points in eastern Pennsylvania. 

 In order to determine the probable evolutionary history of these trees it is necessary to 

 know their present geographical distribution. Are they the result of recent mutations, or 

 the remnants of an older, more widely distributed form? 



The peculiar form of the leaflets is so readily observed, particularly on young trees, that I 

 hope the readers of this journal will make note of their observations and communicate the 

 results to me. Anyone who is willing to assist in this study should examine all the ash trees 

 accessible to him, and let me know approximately the area covered by the observations, and 

 the number of normal ash trees observed, as well as the number of pitcher-leafed trees, if any. 

 It is just as important for the purpose of this study, to know that pitcher-leafed trees do not 

 occur in a given locality as to know that they do. (Fig. 19.) 



George H. Shull. 

 60 Jefferson Road, Princeton, N. J. 



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