igo General Botany 



flourishes only when it grows under such conditions. The diffi- 

 culty in transplanting azaleas, laurels, and rhododendrons from 

 the woods to our lawns Hes largely in supplying conditions favor- 

 able to the fungi that infest the roots. It is easy to supply the 

 proper shade and water conditions for the shrubs, but it is diffi- 

 cult to furnish soil conditions favorable to the life of the fungi. 

 The transplanting of these shrubs is therefore most frequently 

 successful when they are planted in large bodies of soil brought 

 with them from their natural habitat. Such soils may be kept 

 in their natural acid condition by the use of tan-bark extract and 

 alum, but the addition of lime is harmful. In orchids and some 

 ferns the fungi live inside the cortical cells of the roots. Just 

 how the fungi aid the plant is not fully understood ; that they 

 are essential is very clear. A few of these fungi are known to 

 furnish nitrogen to the roots, and they may also aid in the absorp- 

 tion of water and minerals from the soil. 



PROBLEMS 



1. Make a classification of roots and cite examples, on the basis of: (i) their 



origin, (2) their form, (3) their environment, and (4) their function. 



2. Why cannot a dead root system absorb as much water as it did when alive ? 



