SHOOTS 57 
the protected stem. This position is also taken advantage 
of for comparatively safe food storage, and such stems are 
apt to become more or less thickened and distorted by this 
food deposit. 
44. The procumbent type. In this case the main body 
of the stem lies more or less prostrate, although the advanc- 
ing tip is usually erect. Such stems may spread in all 
directions, and become interwoven into 
a mat or carpet. They are found 
especially on sterile and exposed soil, 
FIG. 47. A strawberry plant, showing a runner which has devel- 
oped a new plant, which in turn has sent out another run- 
ner. After SEUBERT. 
and there may be an important relation between this fact and 
their habit, as there may not be sufficient building material 
for erect stems, and the erect position might result in too 
much exposure to light, or heat, or wind, etc. Whatever 
may be the cause of the procumbent habit, it has its advan- 
tages. As compared with the erect stem, there is economy 
of building material, for the rigid structures to enable it to 
stand upright are not necessary. On the other hand, such 
a stem loses in its power to display leaves. Instead of 
being free to put out its leaves in every direction, one side 
is against the ground, and the space for leaves is diminished 
at least one-half. All the leaves it bears are necessarily 
directed towards the free side (see Fig. 18). 
AVe may be sure, however, that any disadvantage com- 
ing from this unfavorable position for leaf display is over- 
balanced by advantages in other respects. The position is 
