vii.] THE ROOT. 59 



that they are always adventitious. Whether true or 

 adventitious, however, the function of the root is the 

 same. 



The root frequently becomes much thickened in peren- 

 nial and biennial herbaceous plants, serving as a reservoir 

 of nourishment for the growth of the sprouts of the fol- 

 lowing season. When the branches or fibres of a root 

 become thickened in this way, as for example in the 

 Garden Dahlia, the root is said to be tuberous. Such 

 tuberous roots much resemble certain forms of under- 

 ground and similarly thickened stem, but differ from 

 them in the absence of leaf-buds. Potatoes and Onions 

 are called roots, but we shall presently show that this is 

 a misnomer. 



3. The STEM always originates in a bud; the primary 

 stem of the plant from the bud of the embryo the plumule. 

 Branches in like manner originate in similar buds formed 

 in the axils of leaves. Hence buds borne in the axils of 

 leaves may be termed axillary; those which terminate 

 a stem or branch, and which, after a winter's rest in our 

 climate, renew the shoot, terminal. Some trees, as Palms, 

 never or rarely develop any other than a terminal leafy 

 bud, excepting when they form a flowering branch. The 

 consequence is, that their stems remain unbranched. 



We have already referred to the distinction between 

 woody and herbaceous stems. Besides erect or ascending 

 annual flowering-stems, many herbaceous plants possess 

 a stem which either creeps upon the surface of the ground, 

 as in the Creeping Buttercup or the Strawberry, or which 

 spreads wholly under the surface, giving off leafy and 

 flowering shoots above and roots below, as Lily-of-the- 

 valley, Wood Anemone, Sheep-sorrel, Sea Maram, and 

 Couch Grass. The underground form of creeping stem 

 is called a rhizome. Beginners are very liable to regard 

 it as a root, and such is the common notion respecting 

 it. The presence of leaves in the very reduced form of 

 minute scales, and the capacity of developing buds at 

 regular intervals, indicate its true stem character. In 

 many plants, underground stem-branches become greatly 

 thickened, like tuberous roots, and serve the same end in 

 the economy of the plant. We have a good example in 

 the Potato. The " eyes " of the Potato are leaf-buds, and 



