H. WORMALD 



187 



Colour of stem 



C'olour of petiole 



Upper side 



Lower side 



The lower side of the petiole is provided with bifid hairs similar 

 to those of the stem ; the petiole, however, is almost invariably rougher 

 than the stem itself. Thus a bine which might be described as "almost 

 smooth!" usually has a "moderately rough" petiole, while a "moderate 

 rough" bine has a "rough" petiole. 



The upper side is channelled by a single longitudinal furrow of 

 varying depth. In the Oregons it is shallow, and the upper surface 

 of the petiole is therefore almost flat. In the English type the furrow 

 is more or less V-shaped in transverse section (except towards the 

 base, where it usually tends to disappear altogether) but is often very 

 variable even in the same plant; there is evidence, however, that in 

 some instances there is an approach to constancy in one direction or 

 the other. One plant represented by three hills (so making nine observa- 

 tions possible) has shown furrows distinctly V-shaped in section on each 

 occasion and the same feature has been noticed in several single hills, 

 while in others the furrow more nearly resembles that of the Oregon 

 form. 



1 It should be noted that these terms are merely relative and no attempt has yet 

 been made to reduce them to terms of size and frequency of the hairs. 



