TENDRIL-CLIMBERS 



43 



as mPisum or Lathyrus, or when, as in the case of Cobaea scandens^z. tips 

 of the branches are furnished with curved claws which aid not only in 

 maintaining contact until coiling has taken place, but also act as permanent 

 attaching organs. 



FIG. 9. Bryonia dioica. a, young spirally coiled tendril ; , expanded and irritable tendril ; c, tendril which 

 has grasped a support ; d, tendril which has not grasped a support, and has undergone the old-age coiling. 



The last-named plants afford instances of the development of a portion 

 (Cobaea, Lathyrus\ or of the whole (Lathyrus aphaca\ of the leaf into 

 a typical tendril. In leaf-climbers the leaf or some portion of it acts as 

 the attaching organ without losing its general character. The petioles of 



