Recognize summer leaves

Take a leaf representative of one species, that is in maturity and taken from a common branch (not on a drageon at the base of the trunk, because its form and its colour would be corrupted). Some high trees give only these low leaves to observe closely (eg Cedrela, Wingnut, Turkish Filbert). We must wait until the fall brings the top leaves on hand! Observe also how the leaf is grafted on the shoot: two leaves from the same point are "opposite", otherwise they are alternate. This helps to distinguish maples (opposite leaves) of sweetgum (alternate leaves) or ash (opposite leaves) of black locust and pagoda tree (leaves, which they somewhat resemble, but are alternate).

Having a leaf in hand, examine:

  • the petiole or leafstalk (the slender stalk by which a leave is attached to the stem), which helps to differentiate the sessile oak and the Pedunculate oak (this one has stalked flowers and acorn and sesille leaves, while the sessile oak has a sessile acorn and a petiolate leaf).;
  • the base (which will be in the form of a heart, right or pointed, in general symmetrical in comparison with the central vein, sometimes assymmetrical - Ulmaceae, lindens);
  • the margin of the blade (enlarged and flattened part of the leaf which captures the sunlight), which can be smooth, possibly with hair (beech), slightly toothed or "denticulate" (almond tree), saw-toothed (charm), doubly toothed (Hornbeam hops), deeply toothed (chestnut) or else lobbed (oaks).
  • the ratio Length / Width with the aid of this grid. This criterion allows to define the "broad " leaves and the "oblong" leaves the report of which (L) / (l), Length / maximum breadth is superior to 1,5.

When touched, a difference between the said pubescent leaves and smooth leaves, although this property has tendency to become blurred with time (Leaf springs are covered with hairs that go with the approach of summer). Others are harsh (some elms, Paper Mulberry). Others are silvery.

Rather than to develop scientifico-empirical descriptions on the form of leaves (heart-shaped base, acuminate apex, etc), I invite you to go through the pictures of a virtual Herbarium, classified according to classical criteria of form: in the submenu to the left.

You can go directly to the questionnaire of identification of leaves, where you will have to give information to type of leaf, ratio L/L, possibly border and particular distinctive: identification questionnaire.

Another criterion of recognition can be the big size of some leaves:

> 50 cm Tree of Heaven, Ailanthus altissima
Prickly angelica, Aralia spinosa
Kentucky Coffee Tree, Gymnocladus dioicus
Bigleaf Magnolia, Magnolia macrophylla
40-50 cm Chinese Mahogany, Cedrela sinensis
Royal Paulownia, Royal Paulownia tomentosa
Sumac, Rhus
30-40 cm Catalpa, Catalpa bignonioides
Ashes, Fraxinus
Horsechestnut, Aesculus hippocastanum
Walnuts, Juglans
Poplar lasiocarpa, Populus lasiocarpa
Wingnut, Pterocarya fraxinifolia
Varnish Tree, Koelreuteria paniculata
Yellowwood, Cladrastis lutea
20-30 cm Oak of Japan, Quercus dentata
Southern magnolia, Magnolia grandiflora

Some species and varieties have a particular colour foliage, which is rather a criterion to choose an original tree, than a recognition indication (for rare trees).


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