THE DIPPERENff KINDS OP STEM. 25 



CHAPTER II. 



THE DIFPERENT KINDS OP STEM. 



The stem may be regarded as that portion of the axophyte 

 which is situated between its two extremities, and which carries 

 the leaves and the flowers. 



The stem exists in all flowering plants, but sometimes, as in 

 Taraxacum dens leonis, the common dandelion, it is hardly 

 developed at all, so that the leaves and even the floral branches 

 appear to spring from the root. These plants were formerly 

 considered to be acaulescent (a without, caulis a stem) ; they 

 have, however, a true stem, but it is so contracted in its growth 

 as to be hidden in the earth. 



The common idea that all the subterranean parts of plants 

 are roots is quite erroneous. The "production of buds and 

 leaves, and the presence of leaf scars, are the distinguishing 

 characteristics of the stem, and the following roots, so called, 

 which "exhibit these appearances, are only its subterranean 

 modifications. 



The rhizoma, {^i^a, a root). This stem pursues an under- 

 ground course, growing horizontally at a depth in the soil 

 which is sufficient to protect the buds on its surface, from 

 which it sends forth annually herbaceous branches into the 

 air, which die down to the ground at the close of the flowering 

 season. In Polygonatum pubescens, (fig. 5,) the annual decay 

 of the foliage leaves on the rhizoma a broad and conspicuous 

 scar, which is not unlike the impression of a seal, and for this 

 reason the plant is commonly called Solomon's seal. 



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