PHYLLOTAXY, OR LEAF ARRANGEMENT 45 



On the other hand, where the internodes are long or the 

 vertical rows few, the leaves tend to assume more broad 

 and rounded shapes, as in the cotton, hollyhock, sunflower, 

 etc. If the blades are much cut and lobed, so that the 



84. — Long internodes and large . 85, — Dissected leaves overlapping 



leaves. one another without injurious shad- 



ing. 



sun easily strikes through, they can bunch themselves in 

 almost any way without injurious shading. The length of 

 the internodes depends, to a large extent, upon the rapid- 

 ity of growth, being usually much greater in vigorous 

 young shoots and the terminal portion of the main stem 

 than in the lateral branches. 



PRACTICAL QUESTIONS 



1. Strip the leaves from a twig of one order of arrangement and 

 replace them with foliage from a twig of a different order ; for instance, 

 place basswood upon white oak, birch upon lilac, elm upon pear, honey- 

 suckle on barberry, etc. Is the same amount of surface exposed as in 

 the natural order? 



2. What disadvantage would it be to a plant if the leaves were 

 arranged so that they stood directly over one another? (24, 25, 27.) 



3. Why are the internodes of vigorous young shoots, or scions, gen- 

 erally so long? (53.) 



4. If the upward growth of a stem or branch is stopped by pruning, 

 what effect is produced upon the parts below, and why? 



5. Why does corn grow so small and stunted when sown broadcast 

 for forage ? 



6. What is the use of " chopping" cotton? 



