100 



THE AMERICAN BOTANIST. 



tion, mechanical injury and sudden changes of temperature. 

 Not until a new spring do their bud-like tips start upward. 



All these subterranean parts are true branches and in the 

 large-toothed sunflower, at least, plainly indicate their rela- 

 tionships by often springing from the stem at some distance 



YOUNG HELIANTHUS GROSSE-SERRATUS 



from the ground and making a decided downward curve in 

 order to enter the soil. A section of the lower part of the stem 

 of this species will afford an excellent study in plant adaptation. 

 Nearest the roots are branches that are plainly destined to be- 

 come subterranean and to produce new plants vegetatively, at 

 the other extreme are aerial branches intent on the production 

 of flowers and seeds, while between them are dwarfed branches, 

 some of them little more than buds that seem to have been in 

 some doubt which way to grow and so have grown little in any 

 direction. This, too, is a good illustration of the old saw 

 that "he who hesitates is lost" for these examples of inde- 

 cision fall with the dead stem and so come to naught. 



In the large-toothed sunflower is also seen an effort to 

 store an unusual amount of food. Large plants have two or 

 three stout straight roots projecting downward at an angle not 

 unlike dahlia "tubers" as the roots of that plant are often mis- 



