54 BOTANY FOR BEGINNERS CHAP. 



Such roots simply cling to the bark of trees, they take nothing 

 from the plant on which it grows. Some water plants produce 

 a large number of roots which float in the water and help to 

 support or moor the plant. The Duckweed, which grows in 

 many of our ponds, is a good example. 



EXPT. 39. Dig up a Grass plant from a field, and examine the roots. 

 Note 



(i) The tap-root is either absent or very short. 



(ii) A large number of roots, which seem to come from either the top 

 of the root or from the stem, and grow without any regular order, can 

 easily be made out. They are called adventitious roots. They are 

 also fibrous roots. 



Aerial Roots. Adventitious roots which hang down in the 

 air are called aerial roots. Epiphytes are plants which possess 

 such aerial roots. The aerial roots of some plants can obtain 

 water from the atmosphere and dissolve any mineral matter 

 which may be blown against them. Many Tree Ferns, Aroids, 

 and Orchids are epiphytes. The Vine may, in some cases, 

 produce aerial roots which hang from the stem in rich profusion 

 and most likely help to obtain water for the plant. Some aerial 

 roots are green, and perform the same work as leaves. They 

 may reach the ground and take root as in the Banyan tree. 

 The Ivy clings to the bark of trees and to old walls by means of 

 aerial roots which are produced from the shady side of the 

 stem. 



Water Roots. The roots of plants which float or grow in 

 water are known as water roots. They may be developed either 

 from stems with floating foliage leaves, or from stems with sub- 

 merged leaves. Floating roots never penetrate even the mud at 

 the bottom of a pond : but the roots of marsh plants go right 

 down into the mud. The ordinary roots of Willows, Alders, 

 and Elms, growing along the sides of streams, often grow from 

 the bank into the water in which they float. Water roots do not 

 produce root hairs. 



EXPT. 40. Obtain a Hyacinth bulb, and place it in a vase of water. 

 Make up the loss of water which will take place by a solution 1 con- 

 taining 



Potassium nitrate . I gram. Calcium phosphate \ gram. 

 Sodium chloride . . \ ,, Water . . . .1 litre 

 Calcium sulphate . . | ,, Iron chloride . . a few drops 

 Magnesium sulphate. \ ,, 



1 Any chemist will make up this solution. 



