STEMS 93 
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. | 
Aerial | tems 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 nodes, 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, ete, 
plants propagate 
themselves inde- 
pendently of seed. 
Herbs, The 
Shrubs, Trees. stems 

of some plants 2 
P Fic. 28.—TRANSVERSE SECTION OF BRANCH OF 
never become LABURNUM, SHOWING Rines or Woop. 
woody, but after b, bark; s, sap-wood ; h, heart-wood. 
a years growth 
die down to the earth ; these are usually green, and plants 
