SCARLET RUNNER ROOT 85 



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 successful, to study the structure 

 of the root in the Scarlet Runner, or the Garden Pea. 



Observations with the Naked Eye. 



Germinate seeds of the Scarlet Runner or of the Pea, 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 



5. The primary root, on the upper part of which are 



6. Numerous secondary or lateral roots. These are formed 

 in acropetal order, and are arranged in regular longitudinal 

 rows, usually four in number. On the youngest part of the 

 primary root no lateral roots are to be seen. 



Observe that particles of the sawdust, c., adhere to the 

 older parts of the roots, while the younger apical parts come 

 out of the soil quite clean : this is due to the fact that root- 



