About Trees

Woody plants absorb more water than they can use to obtain the necessary amount of mineral substances contained in it; the excess is eliminated by the process known as transpiration. This takes place in the leaves and consists of the evaporation of water, regulated to a certain degree by a system of pores that can be opened or closed.

Atmospheric carbon dioxide is the tree’s main source of food. Together with water and by the means of chlorophyll and radiant energy from the sun it is processed by the leaf cells into organic compounds that go into building the major part of the tree’s organs. This process is known as photosynthesis.

The amount of water transpired by trees into the atmosphere is very great and varies not only according to the size and species of the plants but also according to the conditions of the environment – soil moisture, relative humidity of the air, temperature, strength of the wind, etc.

When the leaflets are arranged laterally in pairs on the main leaf stalk, the leaf is termed pinnately compound.

There may be an odd number of leaflets with one located at the tip (terminal leaflet), e.g. the mountain ash, common ash, false acacia (black locust); or an even number of leaflet pairs, e.g. the honey locust and the like.

In some species with large leaves the leaflets are divided even further and these are called bipinnately compound leaves, e.g. the honey locust or Kentucky coffee-tree.