The Root and the Soil. 75 



106. Pricking Off Young Seedlings, i. e., transplanting 

 tliem from the soil in whicli they grew to other soil, 

 where they have more room, is an important preparation 

 for their final transplanting. They should receive as 

 good care after pricking off as before, with which they soon 

 develoj) many new rootlets near the base of the stem, that 

 need be little injured in the later removal (Fig. 32, p. 7-t). 



107. Nursery Trees are Benefited by Transplanting them 

 once or twice before the final planting out, for the rea- 

 sons named above. 



108. Root Pruning (416 k) is sometimes employed as a 

 substitute for transplanting, and is especially useful to 

 trees that form few branch roots, as the hickory and 

 walnut. In this case, the tap root is cut off a few inches 

 below the surface of the soil the year before transplanting. 



109. The Horizontal Extent of Roots is usually greater 

 than is generally supposed. In upright- growing plants, 

 the area occupied by the roots, as a rule, exceeds that 

 covered by the foliage, while in spreading and trailing 

 plants, the roots are probably not often less in extent 

 than the branches. It appears from the observations 

 recorded that even in such plants as the melon and 

 squash, the horizontal extent of the roots usually equals 

 or exceeds that of the runners. As the diffusion of solu- 

 ble matters in the soil water is probably much hindered 

 by the soil particles, the roots of plants need to travel 

 farther after food than do the branches, which develop 

 in a freely circulating medium. Especially is this true 

 of plants growing in poor soil. 



110. The Depth of Roots in the Soil. It appears from 

 the observations recorded that the extreme depth reached 



