HOW PLANTS EAT. 



45 



or nearly so, through the leaves. Examples of it 

 occur in almost all grasses, and in tulips, daffo- 

 dils, lily of the valley, and narcissus. Leaves of 

 this sort have seldom any leaf-stalk; they usually 

 rise straight out of the ground, more or less erect, 

 and their architectural plan is generally quite 

 simple. They are seldom 

 toothed, and hardly ever 

 divided into deeply - cut 

 segments or separate leaf- 

 lets. 



A few more peculiari- 

 ties in the shapes of leaves 

 must still be noted, and 

 a few words used in de- 

 scribing them must be ex- 

 plained very briefly. When 

 the leaf consists all of one 

 piece, no matter how much 

 cut up and indented at the 

 edge, it is said to be " simple " ; but if it is divided 

 into distinct leaflets (as in Fig. 5), it is called 

 " compound." If the edge is unindented all round 

 (as in Fig. 6), we say the leaf is " entire"; if the 

 ribs form small projections at the edge (as in 

 Fig. 4), we call it " toothed " ; if the divisions are 

 deeper, we say it is " lobed " ; and when the lobes 

 are very deeply cut indeed, we call it " dissected." 

 Thus, in order to describe accurately the shape 

 of a leaf, we need only say which way it is veined 

 or ribbed — whether finger-wise, feather-wise, or 

 with parallel veins — and how much, if at all, it is 

 cut or divided. 



Endless varieties, however, occur, in accord- 

 ance with the peculiar place the plant and its 

 kind have been developed to inhabit. In climb- 



FiG. 6. — I, parallel veins, as 

 seen in one great group 

 of plants, the lilies ; II, 

 branching veins, as seen in 

 another great group, the 

 trees and herbs of the 

 usual type. 



