34 
Garden Work 
stem ; then, in many instances, there are the branches, 
which become finer and finer until we reach the tiny twigs. 
Then we have the leaves, and it is here that all stems 
differ from roots. Some stems are almost exactly like 
roots, such as the suckers of roses, while some roots are 
like stems, such as those of trees which are growing on 
a bank where the soil has fallen away from them, leaving 
them exposed to the atmosphere. They then become quite 
like stems. But no true root ever bears anything but 
branch roots, whereas stems bear leaves, which are quite 
different in appearance and structure from the stem itself. 
The stem, like the root, is composed of little tubes, which 
conduct the moisture and food substances through one 
section to the leaves, and, after they have been manu- 
factured there, pass them through another section back to 
the various points of growth. Stems, like roots, are 
covered with a skin or epidermis. In the stems of annual 
plants this skin is thin and transparent, but in other stems 
layer after layer is added to it, until w T e get a bark 
consisting of many layers, which, in the case of the Scots 
Pine, breaks up into many scale-like parts, or, as in the 
Beech, Apple, Cherry, &c., remains in a thick layer. 
Stems have special breathing pores, so that they can have 
an interchange of fresh air. In annual stems we may 
have stomata (pores) in the thin skins, but in the thick 
bark these are impossible. In their place are lenticles. 
These can be plainly seen as little excrescences on the 
bark of the Elder. They are, in reality, little holes filled 
with a host of tiny oval cork cells, exactly like sand in a 
filter, and through these the stem breathes. 
All stems are made up of layer upon layer. First we 
