88 THE PHYSIOLOGY OF PLANTS 



pricking out the seedlings, the young tap-root is always damaged, 

 and consequently the lateral roots soon make their appearance, 

 so that the number of the absorptive organs is increased. We 

 are more concerned with the woody plants which the gardener 

 cultivates for commercial purposes or for his own use. In 

 both cases it is necessary in their culture to pay attention to 

 the portability of the plant. This is only attained when the 

 whole root system occupies a very small space. Trees which 

 are left to themselves develop where they are first grown a 

 long tap-root, by which they are best fixed to the soil, and 

 absorb from the deeper layers of the soil the necessary food 

 material. The development of these deep-rooting plants is a 

 relatively slow one, but correspondingly lasting. Trees which 

 have been transplanted in their youth, and have therefore 

 suffered an injury to their tap-root, produce near the wound 

 several lateral roots, which grow on unhindered in a horizontal 

 direction without much branching. To take up such trees 

 requires considerable labour. Besides, with such diverging 

 roots they are very troublesome to plant, as exceedingly large 

 holes must be prepared for their reception. The general 

 remedy for this is to saw ofi" the long lateral root, so as to 

 reduce the root system to a more convenient size. In doing 

 so, however, the old wood is cut, and only few adventitious 

 roots are formed, and their development is slow and weakly. 

 The few greatly reduced roots give to the tree only a feeble 

 hold on the soil, and produce only few absorptive organs, and 

 cause therefore a considerable interruption of growth, which 

 prevents the tree from attaining any considerable development, 

 and causes premature death. 



A tree intended fop transplantation must have a root system 

 consisting- of a great number of short branches provided with 

 many rootlets, so that the whole absorptive system is limited 

 to a small area. 



The large number of rootlets represents the greatest possible 

 area of absorption, and at the same time a network which will 

 take firm root of the soil, and cause the rapid formation of a 

 ball of roots, which enables the transplanted tree to establish 

 itself. 



Such a much-branched root system, forming a nest or ball 



