EXTENT OF ROOTS 3 I 



red clover roots more deeply than white clover, and almost all 

 plants have distinct and peculiar habits in this respect. 



7. The character and extent of root-development is not, how- 

 ever, altogether dependent upon the species of the plant con- 

 cerned, but is materially influenced by external circumstances, 

 such as the texture of the soil, and the amount of water in it. 

 In deep open soils and loose sands the root-system of a plant 

 is much larger than that of a similar plant grown in compact 

 heavy ground. 



In soils which are not water-logged, increase of moisture up 

 to a certain extent increases the branching of the root, and 

 excellent examples of the influence of water, coupled with good 

 air supply, are seen in well managed plants in pots, and also 

 among plants growing near wells and in drain pipes ; the latter 

 in some instances become completely blocked by the large 

 number of fine rootlets of trees growing in their neighbourhood. 



The root-system is also considerably modified by the total 

 amount and kind of the manures or food-materials present 

 in the soil. Up to a certain point an increase of nutrient 

 substances increases root-developtnent ; an excess hinders it. 



Mutilation influences the development of the root-system. If 

 the growing-point of the tap root of a cabbage or tree is cut off' 

 its further elongation is prevented, but the secondary roots make 

 up for the loss by more vigorous growth and often many adven- 

 titious roots arise near the cut end. 



In order to properly cultivate plants of all kinds it is very 

 important to study the habit or manner of branching of their 

 roots and the relative proportions of the thick tap and second- 

 ary roots to the fine ramifications to which they give rise and 

 which spread through the soil in all directions. The proportion 

 of root-system below ground to the branches and leaves above is 

 also worthy of attention. 



The adaptability of plants to the various kinds of soils, their 

 need of water, the cultivation which the ground should have and 



