78 FIELD, FOREST AND FARM 



bed with tiles. The tap-root of the young tree 

 pushes downward until it reaches this barrier, where 

 it is straightway forced to stop growing in depth 

 and compelled to send out lateral branches. 



"The kind of root we have thus far been talking 

 about is primordial, original; every plant has it on 

 emerging from the seed; it appears as soon as the 

 seed germinates. But many plants have other roots 

 that develop at different points of the stem, replacing 

 the original root when that dies, or at least coming 

 to its aid if it continues to live. They are called 

 adventitious roots, and they play a highly important 

 part, notably in certain horticultural operations such 

 as propagating by slips and layers, which we will 

 talk about later. 



"Besides these two operations, the object of which 

 is to multiply the plant, it is customary to prompt 

 the growth of adventitious roots either for the pur- 

 pose of fixing the plant more firmly in the ground 

 or in order to increase its yield. The best way to 

 attain this result is to bank up the earth at the 

 base of the stalk. This process is sometimes called 

 earthing up. The buried portion soon sends out a 

 great number of roots. Indian corn, for example, 

 if left to itself is too poorly rooted to resist wind 

 and rain, which beat it down. In order to give it 

 greater stability the farmer earths up the corn. In 

 the earth banked up at the base of the stalk bundles 

 of adventitious roots form and furnish the plant a 

 firmer support. 



"Wheat stalks bear on their lower ends buds 



