18 STRUCTURAL BOTANY 



a little above their extreme tips. This is because these 

 parts of the root are clothed with very fine root-hairs 

 (see Fig. 29, p. 77), which have withered away from 

 the older parts. These root-hairs are barely visible 

 to the naked eye, and must by no means be confused 

 with the rootlets or fibres already described, to which 

 they bear no resemblance in structure, as we shall 

 find when we come to the microscopic work. Each 

 growing-point of the root and its branches is covered 

 by a root-cap (see below, pp. 78 and 86). We notice 

 as conspicuous differences between the root and the 

 shoot, that the former bears no leaves and is not 

 green in any part. 



We shall find a young seedling more convenient for 

 studying the root than an older plant. On such a 

 seedling it is possible to make out that the branches 

 of the tap-root are not arranged irregularly, but form 

 four vertical rows. 



B. REPRODUCTIVE ORGANS 

 a. The Flowers 



The branches which bear the flowers do not at first 

 differ in any way from ordinary vegetative branches. 

 They arise in the axils of leaves, and for some time 

 bear leaves themselves in the usual way. But soon 

 the production of leaves ceases, and from that time 

 onwards the branch bears flowers only. Each flower, 

 may itself be regarded as a modified branch (borne on 

 the main branch), the leaves of which differ greatly in 

 arrangement, form, structure, and colour from the 



