o4 OF THE STEM. 
that this form of a principal, or tap-root, is lost from 
changes taking place in it, or some part of it, by 
growth; as in the Peony, Dahlia (pl. 9. f. 1.), which 
consists of a bundle of thickened roots; or, as in the 
meadow Saxifrage, in which the fibres of the root are 
thickened at intervals into round bodies, and the whole 
root assumes a necklace-like form. Asarule no leaves 
or buds are to be met with on roots, and when these 
are found upon parts of a plant growing under ground, 
such portions are considered to be underground stems 
rather than roots, as in the Potatoe, which is filled 
with what are termed eyes, or buds, and is considered 
to be a thickened underground stem furnished with 
buds, from which new plants can be produced. The 
principal use of the root is to give stability to the 
plant, and to supply it with nourishment by means of 
the numerous fibrils or root-lets, which are thrown out 
into the soil; or to lay up a store of nourishment for 
a future period; as in the Carrot, Dahlia, Peony, &c. 
If a young plant, as a Radish for instance, be cut 
through lengthways, there will be seen a part which 
divides the stem from the root, which is considered to be 
the vital part of the plant, and it is termed the collar, 
neck, or crown (pl. 9. f. 2. ¢.). 
OF THE STEM. 
28. The Stem is that part of a plant which bears 
branches, leaves, and flowers, or only the latter: but 
there are some plants which are said to be stemless, 
by which is meant that the stem is so short as not to 
be apparent. Usually the stem grows upwards, but 
