Eucalyptus species

Eucalyptus trees (also known as gum trees) have 2 types of leaves: young, or juvenile, leaves are oval and opposite in arrangement, adult leaves are alternate and sickle-shaped. One or other leaf type, or a combination of both, may be present depending on the age and condition of the tree. Use the appropriate ID check.

ID check 1

  1. Leaves are alternate in arrangement, not divided into leaflets and are evergreen.
  2. Leaves sometimes have toothed edges but are not spiny.
  3. Leaves are aromatic when crushed.
  4. Leaves smell of eucalyptus, or rarely of lemon, when crushed. The edges are flat.

ID check 2

  1. Leaves are broad and opposite in arrangement.
  2. Leaves are not divided into leaflets.
  3. Leaves are not indented or are only very shallowly indented into lobes. The fruit is a woody capsule.
  4. Leaf edges are not toothed.
  5. Evergreen tree, the leaves are dark or bluish-green - they smell of eucalyptus when crushed. The bark is usually shredding or flaking.


Eucalyptus tree

Eucalyptus tree © Università di Trieste, Dipartimento di Biologia. Photo: Andrea Moro


They are very large in the wild but seldom reach their full height in the UK.


Peeling or shedding in strips to reveal the pale grey, pink or white-tinged trunk.

Young leaves

Young (juvenile) leaves appear on young trees, and on older trees that are recovering from damage or approaching maturity. Young leaves are opposite in arrangement and usually oval. They are often stalkless and sometimes clasp the twig at the base. They are bluish-green in colour.

Adult leaves

Adult leaves appear on older trees - occasionally young leaves do as well. Adult leaves are alternate in arrangement, sickle-shaped, stalked, leathery and dark green.


Cylinder to urn-shaped, with a cap that falls to release numerous, spreading stamens. There are no petals.


The same shape as the flowers and woody. The flattened apex has 4 teeth that open to release seeds.


Eucalyptus tree leafy twig

Eucalyptus tree leafy twig and flowers.

© Wouter Hagens
Eucalyptus tree young leaves

The young leaves of a eucalyptus tree are oval or circular.

© H Zell
Eucalyptus tree

Eucalyptus tree.

© Università di Trieste, Dipartimento di Biologia. Photo: Andrea Moro
Eucalyptus tree adult leaves

The adult leaves of a eucalyptus tree are long and narrow.

© Forest and Kim Starr


These diagrams explain some of the important tree and plant parts.


Diagram of a flower showing the stigma, stamen, style, petal and sepal

Leaf parts

Diagram of a leaf showing the apex, margin, midrib, vein and stalk

Leaf shapes

These diagrams show the different leaf shapes you might come across on your survey. Leaf shapes are important for identifying trees.

Palmate leaf
A palmate leaf - the leaflets extend from a single point, like fingers from a hand
Palmately lobed leaf
Palmately lobed leaf - the lobes are arranged on both sides of the stalk like a feather
Pinnate leaf
Pinnate leaf - the leaflets are arranged on both sides of the stalk like a feather
Pinnately lobed leaf
Pinnately lobed leaf - the lobes are arranged on both sides of the stalk like a feather

Leaf arrangements

The way leaves are arranged on a stem can be important for identifying trees.

Opposite leaves
Opposite leaf arrangement
Alternate leaves
Alternate leaf arrangement


These definitions explain some of the trickier words and phrases used in these pages.

Alternate – the arrangement of leaves on a stem - the leaves attach at different but alternating points, rather than opposite points.

Anther – the part of the stamen that contains pollen.

Apex – the top or end; the tip of a leaf for example.

Bract – a leaf-like structure, usually found below the flower or fruit.

Bud scale – usually a type of modified leaf that encloses and protects a bud.

Catkin – slender inflorescences made up of small flowers, usually reduced to the male and female parts. Catkins are typical of wind-pollinated trees.

Coniferous – trees that have cones, and needle or scale-like leaves.

Crown – in a tree, everything above the trunk.

Deciduous – a tree that sheds its leaves all at once in the autumn.

Evergreen – a tree that retains its leaves all year round.

Girth – the circumference of something, like the trunk of a tree.

Gland (of a leaf) – a small organ on a leaf that gives out oils or similar substances.

Inflorescence – the arrangement of all the flowers on a tree. The shape is used to help identify the plant.

Key – a tool used to identify groups and species of living things.

Leaflet – a subdivision of a leaf - it may look like a leaf but is attached to the leaf stalk or midrib, not to the shoot.

Lobe – a rounded or pointed section of a leaf, not divided into a leaflet.

Margin – the edge of a leaf.

Midrib – the central vein of a leaf.

Native – a tree that occurs naturally in an area, as opposed to a non-native tree that has been introduced.

Opposite – the arrangement of leaves on a stem - the leaves attach in pairs at the same point, opposite each other, rather than attaching at alternate points.

Palmate – a leaf shape in which the lobes or leaflets radiate from a single point, like fingers from a hand.

Petals – usually larger and more brightly coloured than sepals.

Pinnate – a leaf shape in which the lobes or leaflets are arranged on both sides of the stalk or midrib like a feather.

Pollarded – when the upper branches of a tree have been cut back to encourage new growth.

Sepals – the outermost parts of a flower which cover and protect the flower when it is in bud. They are usually green.

Side shoots – short, spur-like shoots growing from the main shoots.

Spike – an elongated cluster of flowers; a type of inflorescence.

Stalk – the structure that supports the blade of a leaf.

Stigma – the part at the end of the style. It is covered with a sticky substance that pollen adheres to.

Stipule – a small, leaf-like structure, found where the leaf connects to the stem.

Style – a tube-like structure in the centre of a flower that supports the stigma.

Trunk – the woody stem of a tree, before the branches.

Urban forest – the trees in our towns and cities.

Whorl – 3 or more leaves or needles circling around a stem.