OLD AND YOUNG LEAVES. 



849 



therefore aptly termed " crumpled ". Leaves specially noticeable in this respect are 

 those of the many species of dock (Rumex), rhubarb (Rheum), and also of several 

 sprino- primulas (Primula acaulis, elatior, denticulata, &c.). Frequently the 

 crumpling and rolling occur together, leaves with crumpled vernation having their 

 lateral margins also somewhat rolled inwards. 



Young leaves which have just burst from the bud, and still retain the form they 

 possessed there, are very often seen to be " plaited ". The veins of the leaf form, 



Fig. 90.— Unfolding of Leaves. 



1, 2 Wild Cherry {Prumis avium). », * Walnut (Juglans regia). «, 6 Wayfaring Tree ( Viburnum Lantana). 

 ' Lady 's-mau tie {Alchemilla vulgaris). « Wood-sorrel (Oxaiis Acetosella). 



as it were, the fixed framework, and it is only the green portions between which are 

 laid in folds. From the multiplicity in form and division of the leaf- veins, the kind 

 and manner of folding is also very varied. When the leaf -blade is traversed, by 

 radiating veins, as, for example, in the Lady's-mantle (Alchemilla vulgaris), shown in 

 fig. 90''', the leaf is folded in vernation just like a fan; the veins which radiate out 

 in the adult leaf are as yet parallel to one another, and the green portions which in 

 the fully-formed leaf are stretched between the veins, form deep folds, which are 

 closely packed together. The same arrangement occurs when each of the radiating 



