The Plant 
31 
been proved that seeds will not preserve their vitality for 
more than twenty years. 
Before leaving this subject I should like to draw atten- 
tion to the provision Nature has made for the dispersal of 
seeds. We are all familiar with the white, downy heads of 
the Dandelion and the Thistle, which enable the seeds to 
float about in the air; and the winged seeds of the Pine, 
which are carried a considerable distance from the parent 
tree. Some seeds have little spears which enable them to 
stick to animals, while other seed vessels, when matured, 
burst open, scattering their seeds to a considerable distance 
in all directions. This dispersal is to prevent the seeds 
from falling too thickly round the parent plant, and the 
subsequent overcrowding of the young ones. 
CHAPTER IV 
The Plant 
The plant is made up of two principal parts, the root 
and the stem, but each of these consists of other parts 
having certain distinct functions to perform. The root 
holds the plant in its proper position in the soil. It also 
collects and conveys the food substances from the soil to 
the stem, thence to the leaves. It is branched many times. 
Each time the branches get smaller, until at last we get 
the very fine ones, or root fibres. Near the growing point 
of these fibres we find a band of very, very slender root 
hairs. These are of the greatest importance to the plant, 
as it is they which collect all the food substances required 
