116 



SIZES OF LEAF-SCARS 



[CH. 



stage, profoundly affect the whole branch-system later on ; 

 and we shall see that there are numbers of other cases 

 of arrest of onward growth of the twigs to be considered 

 subsequently. 



The leaf-scars are the surfaces of insertion whence the 

 leaves have fallen, covered with a thin protective layer of 

 cork, formed beneath the separation-layer (absciss- layer) 

 which brought about the cutting off' of the leaf from the 

 stem as described on p. 105, and their position of course 

 marks that of the previous leaves i.e. they are closely 

 crowded, opposite or alternate, spirally arranged or distich- 

 ous, accordingly. 



Leaf-scars differ much in size, in shape and in promi- 

 nence ; the latter according as the absciss-layer was formed 

 close to, or further up the leaf-stalk from, the plane of 

 insertion of the leaf 



The following have large leaf-scars : 



Horse-chestnut Walnut Ailanthus 



Ash Elder Fig. 



That is to say in cases where the 

 have a large pulvinus at the base 

 In the following the leaf-scars ar 



Pines 



Yew 



Tamarisk 



Whin 



Buckthorn 



Almond 



Bird Cherry 



Sea Buckthorn 



Sweet Gale 



Beech 



Honeysuckle 



Firs 



Cedars 



Willows 



Furze 



Daphne 



Plum 



Apple 



Hawthorn 



Elm 



Hornbeam 



Spindle Tree 



leaves are large and 

 of the petiole, 

 e very small : 



Laich 



Cypress 



Broom 



Barberry 



Cherry 



Blackthorn 



Pear 



Laburnum 



Birch 



Privet 



SymphoHcarpos. 



