1909] 



HARRIS— LEAVES OF PODOPHYLLUM 



439 



leaves. 



fl> 



the species as "bearing 1-3 similar leaves or sometimes leaflets." 

 The third leaf is frequently small and not peltate, but it may be very 



similar to the others. 



Knowing that more than two leaves are occasionally produced by 

 the flowering stem, and that there appears to be a slight difference in 

 the size and position of the two leaves in normal specimens, two 

 questions occurred to me: (a) To what extent are the two leaves 

 of Podophyllum really differentiated in type and variability? (b) 

 What is the degree of similarity of leaves from the same individual ? 



A satisfactory measure of the area of a leaf so irregular as that of 

 Podophyllum is obviously out of the question. It was necessary 

 therefore to select some character other than size. The degree of 

 lobing seems to be the only practicable one, although this character 

 is not so definite as might be desired, and the determination is subject 

 to considerable error due to personal judgment. 



The margins of the very excentrically peltate leaves are irregularly 

 toothed, lobed, or divided. It is quite impossible to draw a sharp 

 line of distinction between the smaller lobes and the major divisions of 

 the leaf, but I think that personal judgment would rarely vary greatly 

 in the grading of an individual collection of plants. Perhaps less 

 confidence is to be placed in a comparison of two or more lots taken 

 at different times. In sorting the leaves into classes I counted as 

 lobes the divisions extending at least half-way from the periphery 

 of the leaf to the point of insertion on the petiole; divisions less sharply 

 marked than this were not counted. Only normal plants— that is, 

 those having only two leaves— were included in the collections. In 

 sorting material to determine whether there is a differentiation between 

 the upper and lower leaves of a pair, it is important that the appear- 

 ance of the leaf lamina does not influence the judgment in any way. 

 In dividing the nearly opposite leaves into upper and lower, the 

 insertion of the petiole alone was examined. After the relative 

 position of the two leaves was thus decided the counts were made. 

 The first lot of material examined was taken at Valley Park, near 

 St. Louis, Mo., in May, 1906, when the plants were with partly grown 

 fruit In very few cases was there any question concerning the posi- 

 tion to be assigned to the two leaves. All of the countings were made 



