PLANTS IN RELATION TO SOIL, LIGHT, AIR 59 



the soil. Wheii. the growth is rapid, much water is used. 

 The growth of any plant is governed by the amount of water 

 which it can secure through its root system. Oats require 

 504 tons of water to produce one ton of dry matter when 

 harvested; corn 271 tons; peas 477 tons; potatoes 385 tons. 

 These facts show the importance of having plenty of moisture 

 in the soil during the growth of the crops. 



2. Root Hairs on Young Plants. — Plant a few seeds of radlsli, 

 beans or kernels of corn in moist sand in a glass jar or bottle with 



Fig. 37. — Germinating oats and barley showing the young roots with numerous 

 root-hairs. (Productive Farm Crops.) 



wide mouth. Wrap some dark or black paper around the bottle to 

 keep out the light (Fig. 36). Place in a warm room and Avater a 

 little every day for a week or so. As the seeds start, the roots seek 

 darkness and the leaves seek light. Remove the paper and observe 

 the roots on the inside surface of the glass. By looking close, the 

 plush-like root hairs will be seen on the young roots. 



Eoot hairs are formed on the fibrous roots of plants. They 

 are of a velvety nature. They are useful to the plants in 

 absorbinar moisture from soils. 



