14 



down 30 feet into the earth, and those of some trees 100 feet, you will 

 quickly see that it is not very likely that you have ever seen all the roots 

 of a plant. 



should grow 



So if 

 some 



/ 



Fio^. 13. Showinir root hairs 

 on seedlini,' of a bean iilant. (a) 

 natural appearance ; (b) some 

 magnified. 



you would know all you could about them, you 

 plants in your own rooms. Take some bean, 

 pea, radish, or other seeds and place them 

 between folds of moistened black cloth or 

 flannel. Be sure to keep the cloth moist. 

 In a few days the seed will have ger- 

 minated and the stem and roots will each 

 be an inch or two long. Now notice that, 

 about a quarter of an inch from the tip 

 the root is covered with a fringe of delicate 

 whitish hairs. So delicate are they that if 

 you touch them you will destroy them. 

 These are known as root hairs and they are 

 the feeding organs of roots. It is very dif- 

 ficult to see them in a plant pulled out of the 

 soil, because they have been destroyed by 

 the pulling out. However, if by the greatest 

 care, you can pull out a plant without des- 

 troying them you will find these little root 

 hairs near the tips or new parts of all the 

 roots. As the roots grow, the root hairs keep 

 falling off the older parts and new ones grow 

 on the newer parts. Hence you will see that it is at the ends of their roots 

 that plants take in food and water from the soil, and that the older parts 

 merely serve to carry these up to the stem. How many of you have ever 

 watered trees growing on your lawn or in the garden, and in doing 

 so have poured the water just close to the trunk or stem of the tree 

 where the old parts of the roots grow? If you have, 

 do not forget the lesson you have just learned ; and 

 the next time you water trees, pour the water a little 

 further away from the stem or the trunk, so that it may 

 quickly soak in to where the tips of the roots are growing. 

 Take one of the little bean plants when the root is 

 about ^ of an inch long, and make small marks upon the 

 root about 1/16 of an inch apart with a pen dipped in 

 India ink. Wrap the bean in damp cotton wool, allowing 

 the marked root to be free. Fill a small bottle with water 

 and place over its mouth a piece ofcard board with a hole 

 in it. Hang the bean plant through this hole leaving the 

 root free in the water. Allow it to grow in a dark place 

 two or three days. Take it out and notice the position 

 of the marks on the roots. You will find that the marks 

 near the tip are now at unequal and greater distances apart, whereas 

 those farther back are little changed in position. This shows you 

 that the region of growth is near the tip of the root. This is of great 

 importance in the root growth of plants, because it gives the roots the 

 power to push their way in and out among the particles of the soil. 



Fig. 14. Showing- at (a) 

 the marks on the root 

 of the bean plant, (b) 

 The same marks after 

 •2 (lays, thus showing 

 the region of growth. 



