92 ELEMENTS OF BOTANY. 



the midrib (in pinnately veined ones). Such divided leaves 

 are shown in Figs. 69 and 70. 



In still other leaves, known as compound leaves, the petiole, 

 as shown in Fig. 75, or the midrib, as shown in Fig. 76,-bears 

 what look to be separate leaves. These differ in their nature 

 and mode of origin from the portions of the blade of a 

 divided leaf. One result of this difference appears in the fact 



Fig. 75. — Tlie Fall ol the Horse-phestnut Leaf. 



that some time before the whole leaf is ready to fall from the 

 tree or other plant in autumn, the separate portions or leaflets 

 of a compound leaf are seen to be jointed at their attachments, 

 just as whole leaves are to the part of the stem from which 

 they grow. In Fig. 76 the horse-chestnut leaf is shown 

 at the time of falling, with some of the leaflets already 

 disjointed. 



