148 PRACTICAL BOTANY 



ROOT 



i. Herbaceous Type 



Observations on the structure of the root may be 

 made on the seedling of Helianthus, but as even the 

 tap-root of this plant when young is only of small size, 

 it will be found more convenient, and as a rule more suc- 

 cessful, to study the structure of the root in Phaseolus. 



Observations with the Naked Eye. 



Germinate seeds of Phaseolus multiflorus (the Scarlet- 

 Runner) in wet sawdust, or pure vegetable mould, till the 

 primary root has attained a length of six to eight inches. 



Note with the naked eye 



1. The seed, from which the testa can easily be 

 removed, disclosing 



2. The two fleshy cotyledons : between these 



3. The plumule, which develops early as a stem, 

 bearing foliage leaves. 



4. Below the cotyledons a short hypocotyledonary 

 stem, not clearly marked off externally, except by 

 colour, from 



