6o 



THE FLOWERING PLANT. 



In the former case, the petiole is continued into what is evidently 

 the common leaf-stalk, at the base of which are jointed a pair of 

 leaflets, while it is terminated by an odd leaflet 

 jointed in the same manner. This, then, is a 

 pinnate leaf. The three leaflets in the clover 

 are all attached to the end of the petiole, which 

 is the only common leaf-stalk. We have here, 

 therefore, a palmate leaf. The general appear- 

 ance, however, is usually a sufficient guide. 

 The leaflets of the palmate leaf are either all 

 sessile or with stalks of equal length, while in 

 the abbreviated pinnate leaf the terminal leaflet 

 appears to be stalked even when the other two 

 are sessile, for the common leaf-stalk seems 

 to belong to it. Similarly, when the lateral 

 leaflets are stalked, the terminal one apparently 

 has a longer stalk. The lower part of this 

 apparent stalk is, however, common leaf-stalk. 

 A compound leaf may even be reduced to one 

 leaflet, and is then liable to be mistaken for 

 a simple leaf. In the barberry, for example, 

 the small leaves are jointed on short stalks. A 

 simple leaf is not jointed in this way upon its 

 petiole. The inference that it is a reduced com- 

 pound leaf is borne out by comparison with the closely allied 

 yellow-flowered mahonias frequently found in gardens. Here 



FIG. 24.— Pinnate 

 Leaf. 



Fig. 25.— Ternate Leaf of 

 Strawberry. 



Fig. 26.— Palmate Leaf of Horse- 

 Chestnut. 



the leaves are normally pinnate, with a terminal and two to four 

 pairs of lateral leaflets. The ash presents a similar case. The 



