Identifying Common UK Willow Species by Leaf

Why Willow Leaves Are Worth Learning

Few trees are as generous to the casual observer as the willow. They grow along nearly every riverbank, canal and damp field edge in Britain, they root from cuttings so easily that a fallen twig becomes a tree, and they have been cut and woven here for thousands of years. Learning four species by leaf alone is entirely achievable on a single country walk, and once you can do it, every path beside water starts to read like a map of the landscape: what floods, what drains, what has been coppiced, and what is worth cutting for a basket.

What to Look at on a Willow Leaf

Every willow leaf sits singly on the stem, never in opposite pairs, and that alone rules out most of the confusion. Beyond that, run through a short list before you decide.

• Shape: estimate length against width. Long and thin, or broad and rounded?
• Margin: smooth, finely and evenly toothed, or wavy and irregular?
• Underside: silky silver, grey felt, or plain green?
• Edge: does the margin roll under, hiding the underside from above?
• Stipules: look for small ear-shaped leaflets where the leaf joins the twig — large and leafy on some species, absent on others.
• Habitat: riverbank, wet meadow, or dry hedgerow?

White Willow and Crack Willow: The Riverside Pair

These two are the tall riverside willows, and they are the ones people muddle. Both carry long, narrow, lance-shaped leaves with finely toothed margins, roughly 5–10 cm long.

White willow (Salix alba) is the paler of the two. Its young leaves are covered in fine silky hairs on both surfaces, and the underside stays silvery-white all season. Hold a leaf up: if the tree looks frosted from a distance and the undersides are bright silver, you have white willow. It favours lowland flood plains and slow rivers, and its grey bark becomes deeply fissured with age.

Crack willow (Salix fragilis) looks darker and glossier. Its leaves lose their hairs by midsummer, so both surfaces read as green, and the toothing is coarser and slightly irregular. The reliable test is the twig: crack willow twigs snap cleanly at the base with a sharp crack rather than bending, which is exactly how it earned its name. Look for broken litter under the tree after a windy spell.

The two cross freely, so many riverside willows are intermediates. If it half-snaps and half-shimmers, that is a fair answer — note it and move on.

Goat Willow: The Broad One

Goat willow (Salix caprea) is the odd one out, and the easiest to be sure of. Its leaves are broad and oval, 5–10 cm long but nearly half as wide, dark green and slightly wrinkled above, with grey felted undersides and prominent veins. The margins are wavy and only faintly toothed, and the leaf tip often twists to one side.

It is not a river tree. Look for it in hedgerows, on woodland edges, railway banks and rough ground, often as a shrubby, multi-stemmed tree. In February and March its fat silvery catkins open before the leaves — the pussy willow of hedgerow walks and school nature tables. Male catkins turn gold with pollen and are noticeably larger than the female ones.

Osier: The Basket Willow

Osier (Salix viminalis) has the longest, narrowest leaf of the four: 10–20 cm, often six times longer than wide, with margins rolled right under so the underside is hidden from above. The upper surface is a slightly glossy green; the underside is densely silky white. Stand beneath an osier bush and it glows silver.

It grows as a multi-stemmed shrub in wet ground, osier beds, canal sides and damp corners, and it is the classic basketry willow. If you are cutting material for weaving, osier rods are supple, long and straight. White and crack willow suit larger stake-and-strand work, while goat willow is too brittle and short-jointed for fine baskets — though its whippy young growth is pleasant for rustic hurdles and garden obelisks.

Catkins as a Second Clue

If the leaves are not quite out, catkins will carry you a long way. Goat willow flowers early, in February and March, on bare wood — big, silvery, then golden. Osier catkins appear roughly with the leaves in March and April and are slender and silvery. White and crack willow catkins open alongside the leaves in April and May and are narrower still, with white willow catkins tending to appear on the same shoot as the expanding leaves.

Combined with habitat — flood plain, wet bed, or dry hedge — you should be able to name most willows you meet. And if a tree refuses to fit, that is usually the honest answer: a hybrid, and a fine excuse to come back in another season with a knife, a basket and a second look.