The most widely used method for determining the identity of a tree is
the leaf - particularly the shape of the leaf . There
are leaves which consist of one part, and others which consist of a plurality
of partial leaves that are found on the petiole (composite leaves). The
designations of the different leaf shapes are usually chosen according
to the geometric shapes. Most often, a tree leaf is oval, round, triangular,
heart-shaped or lanceolate.
Leaves which are composed of a stem with several separate leaves are known to us, for example, from ash trees. Sitting at the end of a symmetrical row of leaves is a single leaf - in other words, an odd-pinnate (e.g., Tree Of Heaven). If this end leaf is missing, it is considered to be paripinnate. Partial leaves, which similarly to chestnut leaves are posed from a central point, are called palmate. If all the partial leaves do not stem from a central point, the leaf is called 'foot-shaped'(Podophyllum pous).
Another characteristic is the edge of the leaf. Leaves rarely have perfectly smooth edges. Most are dentate like Apple, Birch, Aspen, Linden, and others, or serrated like Beech leaves. A typical representative of sinuate or lobed leaves is Oak.
In addition, the leaf arrangement (phyllotaxis); on the branch is a characteristic for tree identification. If the leaves stand at regular intervals and symmetrically on either side of the branch, they are said to be oppositely arranged. If the leaves are alternately arranged on the right and left of the branch, they are said to be alternate. For further tree identification, the colour of the leaves (e.g. pale green, yellow green, medium green, dark green) and the pubescence are helpful. There are trees that have leaves which are densely felted on the underside of the leaf. A good website for easy identification of a tree based on the leaf you find under the section leaves identification.
In winter, only bark characteristics and branches with buds are available on the tree for identification, in case there are no fallen leaves lying on the ground. Also when in a leafier state, the bark gives additional clues to understanding which tree is involved. The structure of the bark can mainly be smooth or cracked. Some bark of old trees are marked by deep furrows. In the case of individual species, such as planes (Plane Tree) for example, small sheets of bark dissolve themselves and flake off the tree like scales. The colour of the bark is also a typical characteristic of a tree. A generally well-known one is the white bark of the Birch tree. Similar bark with whitish areas is also characteristic of the White Poplar. Bark colour can be from light brown to reddish tones on gray or dark brown. Tree identification from the bark of the tree is, nonetheless, a rather advanced task that should be left to the experts, since it requires a lot of practice.
Fruit is a very characteristic feature for tree identification. Unfortunately, this feature is only available in mature trees for a brief time during a given year. Besides collecting fruit like apples, pears etc., there are drupes in deciduous trees (cherries, plums, etc.), nuts (including beechnuts and acorns) and air-borne fruit, the seeds of which have wing-like formations (maples, ashes).