experime:^t station report. 325 



the lobes are usually arranged around a common center, and when 

 there are two leaves, the blade is one-sided as a rule. In addition 

 to the variations that may be shown by a photo^engraving, there 

 are tints of green and pnrple and variegation or mottling that are 

 very striking to the eye, particularly when freshly unfolded. 



Erom a superficial study of the colonies of these plants, it seems 

 likely that great variability Ava,s bestowed upon some and a con- 

 siderable! amount of uniformity upon other groups that may have 

 a recent common ancestrv. 



MULBEREY LEAVES. 



Another instance of variation in leaf forms is well shown in the 

 Mulberry {Moms alba L.) as met with in the wild condition in the 

 neighboring woods. To illustrate this a plate has been prepared 

 of some of the leaves that were gathered from the same small 

 pilant. In this case, the leaves with the margin most nearly en- 

 tire are from twigs that seem to have had the best opportunity 

 foT developinent ; that is, certain twigs of unusual length of the 

 season's growth, show leaves that are generally well filled out, 

 and, on the other hand, the small leaves upon abbreviated side 

 shoots are very irregular in outline. While this theory in a general 

 way seems to be sustained by the facts as interpireted by a study 

 of the plant, it is, however, true that striking exceptions are found ; 

 for example, there may be a leaf of the entire type and one much 

 lobed, borne next to each other, as shown near the middle of Plate 

 XXII. 



It goes without saying that the mulberry is a species in which 

 the form of the leaf has not become firmly fijsed. Whether it is 

 tending toward the lobed shape or not, it is difficult to decide; 

 that more than one elementary species is in the making, is another 

 matter requiring further study. For the present, it cannot be 

 more than recorded that upon the same plant the form of the leaf 

 may vary greatly and in such species the full description needs to 

 include the fact. 



It deserves mentioning that another type of variation is met 

 with in the mulberry, namely, the formation of "twin leaves ;" 

 that is, union in part of two leaves both as to the petiole and a por- 

 tion of the blade. A case in point is shown above the middle in 



