FACTS ABOUT LEAVES

We found in an earlier lesson that all of our farm plants have roots,
stems, leaves, flowers, fruit and seeds. We studied the root first as
being the most important part of the plant to the farmer. The seed was
the next part studied, for that was considered the next most
important, because the seed is the main reliance for new plants. The
part next in importance is the leaf and that we will now study.

If you will go into the field and observe the leaves on a number of
plants, you will find that the following facts are true:

They are all green.

They are flat and thin.

Many of them are very broad.

Some of the leaves on a single branch are larger than others on the
same branch, and some have longer stems than others.

Most of them have a rather dark glossy upper surface and a lighter
rougher under surface.

[Illustration: FIG. 59.
To show transpiration. Plant _A_ was set in the sunlight, plant _B_
was left in the darker part of the room. _A_ has transpired much more
than _B_, showing that sunlight is necessary for this work.]