232 TEXTBOOK OF BOTANY 



between the ends of two such veins, and this is why many 

 dicotyledons (though by no means all) have leaves with more 

 or less irregular outlines. If the indentations of the margin 

 are shallow, the leaf is toothed. The cherry, apple, and elm 

 have toothed leaves. If the indentations are deeper, as in 

 the leaves of the common maples and the grape, the leaf is 

 lobed. Sometimes the teeth, as in some grasses and sedges, 

 or the lobes, as in holly and thistle leaves, are stiff and sharp- 

 pointed ; they serve the same protective purpose as do sharp- 

 pointed hairs and spines. If the indentations cut down to 

 the midrib, as in the pea, or to the base of the leaf, as in the 

 horse-chestnut, the leaf is divided, and its parts are called 

 leaflets. 



Divided leaves are of two kinds with reference to the 

 arrangement of the leaflets, and this arrangement is connected 

 with the course of the veins. In many netted-veined leaves 

 there is a single midrib, which gives off branch veins on 

 both sides ; these branch veins branch in turn, and so on. 

 The cherry leaf has this arrangement. If a leaf with the 

 veins so arranged is divided, the divisions cut down from 

 either side to the midrib ; the leaflets then are attached on 

 both sides of the midrib as the divisions of a feather are 

 attached to the quill. The leaf is pinnately divided. The 

 bracken fern has pinnately divided leaves ; so have roses 

 (Fig. 138) and peas. Some netted-veined leaves, instead of 

 a single midrib, have several large veins that start from a 

 common point at the base of the blade and run out in differ- 

 ent directions toward the edges of the leaf. This arrange- 

 ment is seen in maple and grape leaves. If such a leaf is 

 divided, the divisions cut down to the base of the leaf, and 

 the leaflets are all attached to one another at their bases, 

 somewhat like the fingers of a hand. Such a leaf, for exam- 

 ple that of the horse-chestnut or of the clover, is palmately 

 divided. The leaflets of a divided leaf, whether pinnately 

 or palmately divided, may themselves be toothed, lobed, 



