108 DIFFERENT FORMS OF STEMS. 



those of the Onion, Hyacinth, Lily, &c., are in reality under- 

 ground stems. It was formerly stated (. Ill 113) that the 

 real distinctions between the Root and the Stem consist, in the 

 contrary directions of their growth, and in the tendency of ab- 

 sorbing fibres to arise from the former, whilst the latter gives 

 origin to leaf-buds. Now the base of the bulb is the real point 

 of division between the stem and root ; for, whilst all below it, 

 namely the fibres which really constitute the roots, has a ten- 

 dency to grow downwards, the mass of the bulb, together with 

 all above it, has a tendency to grow upwards. Further, the 

 scales of the bulb are in reality but leaves, changed from their 

 usual character and aspect, or metamorphosed ; and at the base 

 of every one of these scales, is found a little bud, occupying the 

 same position in regard to it, as the buds to the leaves on the 

 higher parts of the stem (. 301). Thus we perceive, that here 

 the stem is in a very contracted state ; the internodes not being 

 developed, and the leaves and buds of several nodes arising close 

 together. The difference between one of these scaly bulbs, there- 

 fore, and the solid fleshy expansion of the root which constitutes 

 a carrot or parsnep, is at once evident. 



150. But stems are sometimes so completely changed, in their 

 direction as well as form, that they can scarcely be recognised as 

 such, except by their producing a regular or symmetrical ar- 

 rangement of leaf-buds.* Thus they sometimes creep along the 

 ground, or even just beneath it, sending up buds, which develop 

 themselves into branches, at intervals. Of this kind is the 

 rhizoma or root-stock of most British Ferns, which creeps 

 above ground in some species, and below in others ; and the 

 Ginger-plant of tropical countries has a stem of the same cha- 

 racter, which really furnishes Ginger, although this is commonly 



* The mere production of leaf-buds does not constitute a sufficient character to 

 separate stems from roots ; for a great number of roots, when exposed to the air, 

 or when very near the surface, will give origin to leaf-buds. Elms and many fruit- 

 trees afford familiar examples of this fact. Besides, one very common mode 

 adopted by Gardeners for propagating some plants (such as the Pelargoniums), is 

 to cut a portion from the root, and put it in the ground, leaving the upper part 

 uncovered ; from this, in a very short time, a number of leaf-buds show them- 

 selves ; but these are without any regular arrangement. 



