INTRODUCTION 6 



It not only consists of the stem bearing its green 

 leaves and ultimately producing the mauve flowers, 

 and of the root with its fibrous branches, but it also 

 forms the potatoes themselves (or tubers, as they are 

 called), which we eat. Now these potatoes, as every 

 one knows, grow, like the root, underground, borne on 

 subterranean branches. Both they and the branches 

 which bear them are colourless, and from their general 

 appearance and position every one who has not learnt 

 Botany at once classes them as roots. But is this 

 their true nature ? 



If we closely examine the branches on which the 

 potatoes grow, we shall find that they bear small scaly 

 leaves (Fig. 2, sc). Similar little leaves (ec) will be 

 found on the potato itself, adjoining the " eyes," and 

 the " eyes " themselves are buds (Id), which grow out 

 into new plants when the potatoes are sown. Leaves 

 and buds, however, are characteristics of stems ; the 

 former are never, the latter rarely, found on undoubted 

 roots. Besides this, a more thorough examination 

 would show that the internal structure and the 

 mode of growth of the potatoes and of the under- 

 ground branches which produce them are those of 

 stems and not of roots. Further, we may sometimes 

 find on the parts of the potato plant above the ground 

 bodies which are intermediate in form and structure 

 between potato tubers and ordinary green branches. 

 For these reasons, all botanists are agreed in regarding 

 potatoes, in spite of their appearance and underground 

 position, as forming part of the shoot and not of the 

 root. In other words, we come to the conclusion that 



