INTRODUCTION 
leaves to the various regions of the plant where growth is taking place ; 
secondly, to bear up and spread out the leaves so that they may obtain a 
suitable supply of light and air ; and, thirdly, to store up reserve food. 
When the stem elongates, the regions at which leaves are given off 
are termed nodes (Latin nodus , a knot), and the spaces between them, 
internodes. In some cases, as in the Pink and Knot-grass Families, the 
nodes are swollen ; and in many quick-growing stems, such as those 
of Bamboos and other Grasses, and of the Carrot and Parsley Family, 
the internodes are hollow or fistular. 
Stems may be developed underground or above ground. Underground 
stems, having no weight to support, do not require to form wood, and 
they are in many cases fleshy reservoirs of food, bearing leaves reduced 
to small membranous scales. The chief forms of underground stem 
are the rhizome, the corm, the tuber, and the bulb. The rhizome, or 
root-stock (often mistaken for a root but distinguished by its scale-leaves), 
is elongated, being made up of many internodes, generally horizontal 
in direction of growth, branched, and often fleshy, as in Solomon’s Seal 
and Iris, giving off adventitious roots, chiefly from its nodes. The 
Water Hemlock ( Cicuta virosa ) is exceptional in having a vertical 
rhizome ; but there are many examples of slender ones, such as those of 
the Lily-of-the-valley, the Sand-sedge, and the Couch-grass. Gardeners 
commonly speak of propagating such plants by “ dividing the root,” 
because a portion of a rhizome bearing a bud and roots is capable 
of growing into a new plant. By a similar mistake the truncated 
appearance produced by the decay of the older part of a rhizome, as 
in the Primrose, has been called a premorse root (Latin prcemorsus, 
bitten off). 
The corm is a short, thick, solid stem, generally of a single internode, 
giving off roots below and bearing buds on its upper surface. The 
Crocus , Snowdrop, Gladiolus , and Lords-and-ladies ( Arum maculatum ) 
are familiar examples. The tuber , represented in the Potato and in 
the Black Bryony ( Tamus communis ), differs mainly in being made up 
of several internodes, so that buds or “ eyes ” are scattered over its 
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