THE LEAF. 



165 



menon occurs in the parsley (Petroselinum sativum) 

 and in a remarkable form of Begonia manicata. 



Further, the leaf of the greenhouse cyclamen 

 assumes a weird aspect when its margin becomes 

 curiously divided up into, as it were, little dissected 

 leaflets, apparently repeating the same freak often 

 met with in the petals of this plant. 



These phenomena of "crisping" appear to have 

 no morphological significance. 



Fig. 44. — Ulmus glabra var. pendula. Showing- leaflets formed at 

 base of main blade. 



Simple leaves may become compound. Leaves of 

 the hazel and elm (Jjlmus campestris) occasionally cut 

 off a small leaflet at the base. In a weeping variety 

 of the feather-elm {Ulmus glabra) great numbers of 

 the leaves on many shoots bore from one to three 

 leaflets (usually stalked) on the petiole below the 

 lamina (fig. 44 a) ; when one leaflet was present, this, 

 which varied greatly in size, was in most cases in the 

 position in which, in the asymmetrically-formed leaf- 

 base, a portion of the lamina is missing. This was 

 also observed in the English elm ( U. campestris) and 



