306 



Plant Physiology 



Klebs has in recent years developed important relations 

 between the continuance of growth and certain external 

 factors. For a few plants he has indicated the conditions 

 tending to maintain vegetative growth and he has con- 



FIG. 76. Effect of conditions on the growth of pine needles : the short 

 needles were produced during the season of transplanting (poor water- 

 supply). 



trasted these with the influences inducing flowering 

 tending toward maturity. These are subsequently re- 

 ferred to (section 225), but it is important here to note 

 that most plants exhibit such complex relations as to 

 render the problem especially difficult. 



