Glossary of tree terms

Alternate: Arranged one at a time along a twig, staggered rather than in pairs, as in the buds and leaves of silver birch.
Bark plate: A flat, hard piece of bark, as on an older sycamore, that breaks away from its neighbours along its edges.
Bud scale: One of the small overlapping coverings around a bud. Scales may be dark, pale, sticky or hairy.
Catkin: A hanging or upright spike of small flowers or seeds, produced in clusters on many broadleaf trees.
Compound leaf: A leaf divided into separate leaflets along a common stalk, as in ash and rowan.
Crown: The upper part of a tree where the main branches and foliage grow. The crown gives a tree its shape against the sky.
Lenticel: A small pore in bark that lets air reach the living tissue beneath. It shows as a pale or dark dash or dot.
Leaf scar: The mark left on a twig where a leaf has fallen. Its shape and small dots show where the leaf's veins once joined the twig.
Lobe: A rounded or pointed division of a leaf blade, as in the five lobes of sycamore.
Opposite: Arranged in pairs facing each other across a twig, at the same height on each side.
Pinnate: A compound leaf with leaflets on either side of a central stalk, like the barbs of a feather.
Samara: A winged fruit that spins as it falls, such as the paired seeds of sycamore and the bunched seeds of ash.
Stand: A group of trees growing together in one area, with its own mix of species, age and shape.
Terminal bud: The bud at the tip of a twig. It is often larger than the side buds and helps show a tree's shape in winter.