64 



LEAVES. 



[section 7. 



a large and very slio\ry petal-like leaf ; the original dry scale is apparent 

 ill the notch at the apex. 



107. Leaves as Spines occur in several plants. A familiar instauce is 

 that of the couiinon Barberry (Fig. 171)- In almost any summer shoot, 

 most of the gradations may be seen between tlie ordinary leaves, with 

 sharp bristly teeth, and leaves which are reduced to a brandling spine or 

 tliorn. The fact that the spines of the Barberry pioduce a leaf-bud iu 

 tbeir axil also proves them to be leaves. 



168. Leaves for Climbing are various in adaptation. True foliage- 

 leaves serve this purpose ; as in Gloriosa, where the attenuated tip of a sim- 

 ple leaf (otherwise like that of a Lily) hooks around a supporting object ; 

 or iu Solanum jasminoides of the gardens (Fig. 172), and in Maurandia, 

 etc., where tlie leaf-stalk coils round and clings to a support: or in the 

 compound leaves of Clematis and of Adlnmia, in which both the leaflets 

 and their stalks hook or coil around the support. 



109. Or in a compound leaf, as in the Pea and most Vetches, and in 

 Cobsea, while the lower leaflets serve for fohage, some of the uppermost 

 are developed as tendrils for climbing (Fig. 167). In the common Pea this 

 is so with all but one or two pairs of leaflets. 



170. In one European Vetch, the leaflets are wanting and the whole 

 petiole is a tendril, while the stipules become the only foliage (Fig. 173). 



171. Leaves as Pitchers, or hollow tubes, are familiar in the common 

 Pitcher-plant or Side-saddle Flower (Sarracenia, Fig. 174) of our bogs. 

 These pitchers are generally lialf full of water, in which flies and other in- 

 sects are drowned, often in such numbers as to make a rich manure for the 

 plant. More curious are some of the southern species of Sarracenia, which 

 seem to be specially adapted to the capture and destruction of flies and 

 other insects. 



Fig. 172. Leaves of Solanum ja.iniinoides, the petiole adapted for flimhing. 

 Fig. 173. Leaf of Lathyrus Aphaca, consisting of a pair of stipules ami a tendril. 



