13 



to notice the very early growth of one of these plants, you would see 

 a primary root which, however, soon disappears and is replaced by 

 secondary roots springing- partly from the base of the stem and partly 

 from the lower joints of the stem. These roots are sometimes called 

 adventitious roots. 



But not only will you notice differences in the length of roots in dif- 

 ferent plants, but you will notice differences in the same plants in differ- 

 ent soils. Sow some beet seed in a soil that is not 

 deeply loosened up, and notice how much shorter 

 the roots are than those grown from the same 

 kind of seed sown in a deeply-loosened up soil. 

 This shows you why farmers in growing such crops 

 as beets, turnips, and carrots always cultivate and 

 loosen up the soil as deeply as possible. 



Again, trace out the roots of a plant, such as 

 grass, grown in a soil that remains wet for a long 

 time in the spring, and then do the same with 



a similar grass plant grown in a soil that dries out , 



earlier in the spring. You will find that the roots ^=^-2,^- _ 



of the grass grown in the drier soil, have extended '^^•"*^'::r^^^ ■ 

 down much more deeply into the earth. The reason ^'^- ''• ro^oroTcorn.'"""°"' 

 for this is, that roots are no fonder of cold water to 



live in than you are, and therefore in a cold wet soil have to spread out 

 very near the surface. In the drier soil they strike down deeply. Now 

 watch the effect when the dry summer days come. The plant on the 

 soil that was so wet wilts away, because its roots are all near the surface 

 and cannot reach down to the water below, whereas the plant in the 

 drier soil, unless the weather becomes very hot and dry, can grow easily, 

 because its roots are down deep in the soil near the water that lies there. 

 Do vou not see from this one reason for underdraining- fields ? 



Once more, trace out for a little way the roots of a grass grown in 

 what farmers call a rich, mellow soil, and then do the same in a soil that 

 is poor in plant food. You will find that the roots in the rich soil have 

 branched very much more than in the poor soil. This is because of the 

 large amount of plant food in the rich soil. Have you ever seen people 

 trying to make a lawn ? If you have, you will have noticed that, in some 

 soils, the grasses remain in separate tufts and do not mat into a good 

 sod. These are the poor soils. But in a rich soil you will have noticed 

 that in a very short time, not more than a year or two, a good close sod 

 has formed, on which you can easily play croquet or tennis or other 

 games. This is because the roots have developed so much more thickly 

 in the good soil, and thus have produced a better growth of grass, and 

 have become more closely matted together, making a firmer sod. 



Now, we have observed a lot of different things about roots. Let us 

 look a little closer at them and see what we can learn about the way in 

 which they push through the soil, how they hold so firmly to it, and how 

 they absorb water and plant food. You have already discovered how 

 very difficult it is to pull up all the roots of a plant without breaking 

 them. When I tell you that the roots of some clovers have been traced 



