STEMS 23 
surface buds, the so-called “eyes,” each situated in a minute 
scale-leaf ; these buds will under certain circumstances sprout 
and give rise to a potato plant. It is clear, therefore, that a 
tuber 1s a stem. | 
Food is stored in the tuber in the form of starch. 
Rattal Stems which come up above ground are said to 
Stems. he aerial, in order to distinguish them from those 
which are underground. Aerial stems may grow straight 
upright ; or they may begin by being upright, and then their 
upper part may curve and trail along the ground; or they 
may creep along the ground, rooting as they go. 
The runner of the strawberry is an example of a creeping 
branch of a stem, which takes root at its nodvs, where leaves 
are also given off, thus producing a new plant. 
Some stems are both subterranean and aerial ; this is the 
case in the sucker, so well known in the raspberry. It arises 
from the stem below the ground, pursues a horizontal course 
for some way, 
then comes above 
ground, and 
finally becomes 
an independent 
plant. 
By means of 
underground 
stems, runners, 
suckers, etc, 
plants propagate 
themselves inde- 
pendently of seed. 
Herbs, The 
Shrubs, Trees. ctor 
of some plants 

Fie, 28.—TRANSVERSE Section or BRANCH OF 
never become — | LABURNUM, SHOWING RinGs or Woop. 
woody, but after b, bark ; s, sap-wcod ; h, heart-wood. 
a years growth 
die down to the earth; these are salle ereen, and plants 
