128 



PLANT LIFE. 



157. Special forms. — Foliage leaves may be modified to 

 serve special purposes without wholly losing their function as 



Fig. 152. — Palmately veined and branched leaf of Norway maple. About half natural 

 size. — After Kerner. 



foliage. For example, the petiole may be made sensitive to 



contact and adapted to wrap about slender objects, like a 



tendril, as in clematis and j^fs, *t 



nasturtium (fig. 154). Such 



plants are called leaf-climb- — ' v 



ers. 



Fig. 154. 



Fir.. 153 .— Pinnately veined leaf of buckthorn, with looped ribs forming a selvedge. 



After Kerner. 

 Fig. 154.— Portion of a plant of the dwarf garden-nasturtium {Trofiaolum minus). 



The long petiole a, ,*, ,1 of the leaf / is sensitive to contact and has coiled about 

 the support and its own stein, st. ~, axillary branch. Natural size.— After Sachs. 



