Bark The tough outer layer on the stem of trees, shrubs and vines. The outer bark protects against damage, cold and water loss. The inner bark, or phloem, carries sugars made in the leaves around the rest of the tree.

Branch A division of a tree trunk that supports twigs, leaves, flowers and fruit.

Broadleaf tree A flowering tree that produces fruits with seeds inside. Many broadleaf trees are deciduous but some, such as holly, are evergreen.

Cone The reproductive parts of a coniferous tree. Conifers have male and female cones. When ripe, the male cone releases pollen, which is carried by the wind to female cones. Seeds then develop inside the female cone while on the tree.

Coniferous tree A tree, such as a pine or fir, that grows its seeds inside cones and has needle-like leaves. Coniferous trees typically have a narrow, conical crown shape. Almost all coniferous trees are evergreen but some, such as larches, are deciduous.

Crown The upper branches and leaves of a tree. Each species has a characteristic shape based on the number and angle of its twigs and branches. Most crowns either have a rounded or crown shape.

Deciduous A tree, such as an oak, maple or birch, that sheds its leaves in the autumn. This allows it to conserve water during the cold months. In the spring it grows new leaves.

Endogenous tree Any tree that grows new wood interspersed with old wood fibres, rather than in a specific area of new growth. Endogenous trees include palms and cacti.

Evergreen A plant, such as a pine or holly, that has leaves all year round. Evergreen plants constantly lose and replace their leaves throughout the year.

Exogenous tree Any tree that grows in width by forming new layers of wood under the inner bark each year. Most trees are exogenous.

Growth layer A layer of a plant’s trunk just beneath the inner bark. It makes new bark on the outside and new sapwood on the inside.

Heartwood The inner core of a tree’s trunk made of old, hardened sapwood. The heartwood gives a tree its strong “backbone”.

Palm tree A tree with a straight trunk and no branches. At the top is a crown of large leaves. Palm trees may grow up to 40 metres (130 feet) tall, mostly in tropical and sub-tropical areas.

Resin A sticky substance produced by trees. Resin helps to seal any wounds in the trees’ bark to protect it from infection. It also traps insects to stop them from eating the plant’s wood.

Sapwood The layer inside a tree beneath the growth layer. The sapwood carries water from the roots up to the leaves. A new layer of sapwood grows each year, appearing as a ring.

Tree A tall perennial plant with a woody stem and branches high above the ground. Its branches, which divide into smaller twigs, spread out leaves so that they all receive as much sunlight as possible. The roots below ground anchor the tree and soak up water and nutrients from the soil. There are two main kinds of tree: broadleaf trees and conifers. Different trees have leaves of different shape. These are often the easiest way to tell different species apart.

Trunk The main stem of a tree. A tree trunk has several layers: the outer bark, inner bark, growth layer, sapwood and heartwood.

Twig A small division of a branch. Leaves, flowers and fruits grow from buds on twigs.

Consultant: Chris Jarvis