THE LIFE AND GROWTH OF SEEDLINGS 29 



Some plants have a fibrous instead of a tap-root system. 

 This is characteristic of grasses. Here there is no main root 

 seen ; but there are several roots, all of about the same length, 

 and these give off smaller roots. A root-system of this nature 

 is not strong enough for a plant that grows very tall, and even 

 in the case of some grasses, such as maize, which grow very high, 

 fibrous roots are not sufficient. The maize develops rings of 

 roots from the stem above ground. These grow downwards, and 

 when reaching the soil they help to keep the plant fixed firmly. 



Besides fixing a plant firmly in the soil and absorbing food- 

 material, roots are often great storehouses of food. They are 

 then usually swollen, as in the turnip, carrot, and beet. The two 

 former contain grape-sugar, whilst the beet has cane-sugar. 

 Plants which have roots capable of acting as storehouses are often 

 biennials, the food that is stored up one year being used the next 

 for the production of flowers and fruit. 



DEPTH AT WHICH SEEDS SHOULD BE SOWN. Seeds should not 

 be sown too far beneath the surface. Small seeds, those, for 

 instance, of plants that are going to be pulled up or transplanted, 

 like lettuce, radish, spinach, are sown broadcast on the surface, 

 for they require very little covering of soil, and after sowing 

 it is sufficient to rake the soil lightly. Even these small seeds are 

 often planted in drills, a more economical method. Drills, as 

 every amateur gardener knows, are tiny furrows from \ inch 

 to 2 inches or so in depth, according to the size of the seeds 

 to be sown. Sweet-peas may be planted i or 2 inches below 

 the soil. Supposing seeds are sown too deep, the plant may not 

 be able to reach the surface. 



The accompanying illustrations of oats planted at different 

 depths show that a grain planted too deep forms a few roots, then 

 when the epicotyl has reached the right level for the plant, a 

 second root-system is formed. If planted much too deep, the 

 plant might have such difficulty in reaching the surface that it 

 might die, or it might be at such a disadvantage, that it could 

 not develop properly. 



In this connection it may be mentioned that the roots of 

 certain plants as they get older have the power of pulling the 



