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L ie External Form of Blades,’ | a 79 
roots oar its under-side, as in the money-wort, Lysimachia 
nummularia, and periwinkle, Vinca minor, floating as in 
many water-plants, climbing as in the ivy, or twining 
(scandent), when it may twine either to the right,’ as in the 
hop or honeysuckle, or more often to the left, as in the 
bindweed (Figs. 113, 114). : 3 
The base of the stem or underground stem is distin- 
guished from the true root by its power of producing leaves. 
_ These are, however, often dry or deciduous, and their pre- 
sence can then only be recognised by the scars they leave 
behind ; and sometimes they disappear so early that even 
the scars can scarcely be made out. In such cases the ~ 
earliest stages of development must be examined in order to 
come to a determination. ‘The underground stem assumes 
"peculiar forms in the rhizome, tuber, and bulb. 
The rhizome (Fig. 108, p. 77) is found in many perennial 
_plants. It may be recognised by the leaf-scars, as alse by 
its putting out a number of adventitious roots from its under 
side, and ascending annual mes 
branches (shoots) into the air Mb : . 
from its extremity or from the ( : 
neighbourhood of the _leaf- Ya, “(a ae 
© 
scars. The buds of these ge 
shoots hibernate beneath the 
ground (Fig. 115). Rhizomes 
are commonly branched, and 
Fic. 115.—Rhizome of Solomon’s seal, 
-hot unfrequently elongated, Convallaria Polygonatunt. a ter-. 
: minal bud from which is developed 
and creep fora distance the next year’s stem; 4 this year’s 
beneath the surface, as for stem ; c, d, scars of the stems of pre-- 
vious years. 
example in couch-grass, 772¢z- 
cum repens ; but are sometimes short and compressed, as in_ 
the J/7zs, solid, or sometimes hollow and divided into 
chambers, as in the water-hemlock, Czcufa virosa. 
The zuber is a thickened fleshy underground stem, with 
' [In applying the terms twining ‘to the right’ and ‘to the left,’ the 
reader must imagine himself in the position of the stem round which 
the climbing plant twines.—ED. ] 
