198 BUDS AND STIPULES 



be to regard the leaf as consisting of two parts 

 (1) the base, with or without foliar expansions, the 

 stipules ; and (2) the upper part or petiole, with or 

 without a foliar expansion, the leaf-blade. 



Sometimes all four divisions are present, as in the 

 Rose ; sometimes the stipules are absent, as in Maples ; 

 sometimes the leaf is sessile, the stalk, stipules and base 

 being undeveloped, as in Gentians; sometimes the blade 

 is absent, and its functions are performed by the flattened 

 petiole, as in most of the Australian Acacias ; sometimes 

 the stipules perform the function of the leaf-blade, as in 

 Lathyrus Aphaca (fig. 294). 



Th&iHeliantfiemum vulgare (fig. 22, p. 20) has stipules 

 and H. oelandicum (fig. 23, p. 21) has none is clear and 

 simple enough, but there are many cases in which the 

 presence or absence of stipules is far from being so easy 

 to determine, and which have been the subject of much 

 difference of opinion amongst botanists. 



For instance, the Composites generally (Daisies, 

 Chrysanthemums, Dandelions, Lettuces, &c.) are said to 

 be exstipulate, but in some the petioles are dilated at 

 the base into appendages which can scarcely be 

 distinguished from stipules. 



In some Crucifers, as, for instance, in Cardamine 

 impatiens, some of the lower leaves have rounded and 

 thickened auricles, which in the upper leaves become 

 prolonged into subulate, obtuse, falcate processes clasp- 

 ing the stem. These are often called stipules. They 



