THE HOOT 31 



similar, but much smaller and more delicate, structures 

 on the roots of other plants, such as pea and bean 

 seedlings. These may often be more easily seen when 

 the roots are held up against the light, and a magnifying 

 glass will be found very useful. Examine also roots 

 growing in water ; some water-plants have no root-caps, 

 but the frog's-bit (Hydrocharis\ if obtainable, furnishes 

 good examples, as also do the duck-weeds (Lemna\ so 

 common on ponds. These roots should be examined 

 whilst still in water, Grow seedlings and cuttings in 

 water, and examine their roots for root-caps. 



Make simple outline drawings of all the plants 



examined. 



Growth in Thickness. 



The youngest part of a root is usually the thinnest ; 

 this is readily seen by observing any of the seedlings 

 already obtained. In most of the plants which have 

 only one cotyledon the roots soon stop growing in 

 thickness, and accordingly all the older roots are of 

 a uniform size : see plants of barley, wheat, maize, 

 grasses, etc. 



In dicotyledonous plants, on the other hand, increase 

 in thickness may go on for a very long time, and the 

 roots in consequence become very thick. Take any 

 opportunity of observing the roots of trees, for instance, 

 elm, oak, beech, apple, etc. Good examples may often 

 be seen in lanes with steep banks, where the roots are 

 frequently left exposed, owing to the soil being washed 

 away. The main roots are often as thick as the main 

 branches of the stem. Interesting cases showing an 

 enormous increase in the thickness of roots can readily 



