USES OF THE STEM TO MAN 
261 
trated by the habit of the ground pine and by the running 
blackberry. A creeping stem may lie beneath the surface 
of the ground, as in the case of the Canada thistle or the 
“ quack ” grass. (See also 
Figure 305, Pteris, and Figure 
311, Club Moss.) 
226. The Duration of 
Stems. — The length of life 
of a stem depends upon its 
habit in producing seeds. An 
annual or herbaceous stem, 
like the morning-glory or the 
lady-slipper, dies at the end 
of the first season, the plant having produced its seeds. 
Other stems, like the trees, last year after year. Some of 
the redwood trees in California are known to be more than 
three thousand years old, and the Cedar of Lebanon, grow¬ 
ing in Asia Minor, is known to live as long. 
227. Uses of the Stem to the Plant. — The stem is of use to 
the plant in being the place for the attachment of leaves, and 
in providing a path for the vessels which 
carry water from the roots where it is 
gathered to the leaves where most of it 
is used. A third use of stems is for the 
storage of food, as in the potato. A 
few plants make use of stems for propa¬ 
gation, as in the case of the strawberry 
and the raspberry (see page 271). 
228. Uses of the Stem to Man. — 
Man makes use of the stem for food, the 
potato being one of the most familiar 
examples as well as a common source of food. Starch is 
also made from potatoes. The stem and buds of asparagus 
are used for food. 
A second use is for shelter. Trees furnish lumber in all 
Figure 249. — Starch 
Grains Highly Mag¬ 
nified, Showing Lines 
of Growth. 
Figure 248. — Indian Turnip. 
