120 



BRITISH PLANTS 



trailing stems and small leaves. The long intern odes 

 are the direct result of weak light ; the small leaves are 

 due to malnutrition, resulting from the impoverishment 

 of the chlorophyll through lack of light. In extreme 

 cases the chlorophyll becomes yellow or etiolated, and 

 ceases to make starch altogether ; the plant then starves 

 to death. 



FIG. 38. EVERLASTING PEA WITH LEAF-TENDRILS AND WINGED STEM. 



(REDUCED.) 



The evolution of the climbing habit may be traced in 

 several of our common British plants. The woody night- 

 shade shows how an ordinary plant may become a twiner. 

 The common fumitory (Fumaria officinalis), and its near 

 relation, the climbing corydal (Corydalis claviculata), give 

 us an idea of one method by which the tendril may be 

 evolved. These two plants are occasional climbers, with 

 large, much-dissected leaves. The leaflets are small, and 

 the whole leaf appears to be more or less sensitive, so 



