The distinctive features of a tree are:
  • Its parts: leaf, thorn, flower, fruit, buds, twig, bark; and
  • Its appearance: height, colour, shape, diameter, age.
In some cases, the amateur can identify a tree by its leaf and the arrangement of the leaves on the twig, together with some consideration, more or less, of its other distinctive features.
It should be noted that the leaves of identical species can vary from tree to tree and even on the same tree. This variation is due to location, exposure to the sun, and to the condition, age and size of the tree. It is desirable to select a leaf that is representative of most of the leaves on the tree.

The science of tree identification is known as dendrology.
More on this important subject later.