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Willow, crack (Salix fragilis)

Scruffy and loud, the crack willow is named after its habit of splitting with cracks and fissures, and how noisy its branches are when they break. It’s one of the largest willows and its leaves are popular with moth caterpillars.

  • Crack willow can grow up to 25m tall.

    Credit: Nature Photographers Ltd / WTML

  • Its female catkins are green in colour.

    Credit: Jason Smalley / naturepl.com

  • Its leaves are dark green on top and light green below.

    Credit: Dmitry Potashkin / Alamy Stock Photo

  • These woolly white seeds are dispersed by the wind.

    Credit: Terry Whittaker 2020 VISION / naturepl.com

  • Its bark is dark brown, developing deep fissures over time.

    Credit: Nature Photographers Ltd / WTML

  • Catkins appear before the leaves.

    Credit: John Duncan / WTML

  • Crack willow is regularly planted to stabilise banks and dykes.

    Credit: Nathan D Costa / WTML

Quick facts

Common name: crack willow

Scientific name: Salix fragilis

Family: Salicaceae

Origin: non-native

The crack willow is hard to tell apart from the white willow. Mature trees grow to 25m. The bark is dark brown and develops deep fissures with age, and twigs are slender, shiny and yellow-brown.

Look out for: mature leaves which are hairless and shiny on top and sparsely hairy below. Catkins appear before the leaves.

Identified in winter by: the twigs which are brittle and make a 'crack' sound when snapped. Yellow-brown, hairless, narrow buds are pressed close to the twig.

What does crack willow look like?

Credit: Nature Photographers Ltd / WTML

Leaves

The oval leaves are similar to those of the white willow, being long and slender, dark, glossy green above and light blue-green below. However the leaves of the crack willow are longer than those of the white willow, and they do not have a covering of fine, silky white hairs on the underside.

Credit: Floralimages / Alamy Stock Photo

Flowers

The crack willow is dioecious, meaning male and female flowers are found on separate trees. The catkins flower in May – the male’s being yellow and the female’s green.

Credit: Terry Whittaker 2020 VISION / naturepl.com

Fruits

After pollination by bees, the female catkins transform into woolly white seeds which are dispersed by wind.

Not to be confused with:

Other willow species which all freely hybridise. Crack willow often hybridises with white willow (Salix alba).

Trees woods and wildlife

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Where to find crack willow

Crack willow is spread across the UK and native to Europe and Western Asia. It is often found growing alongside rivers, lakes and watercourses and is regularly planted to stabilise banks and dykes.

Its catkins flower in May.

Credit: John Duncan / WTML

Value to wildlife

Caterpillars of a number of moth species feed on the foliage, including the puss moth, eyed hawk-moth and red underwing. The catkins provide an important source of early nectar and pollen for bees and other insects, and the branches make good nesting and roosting sites for birds.

Mythology and symbolism

All willows were trees of celebration in biblical times, but this changed over time and today willows are more associated with sadness and mourning. In northern areas, willow branches are used instead of palm branches to celebrate Palm Sunday.

Willows have long been associated with sadness and mourning.

Credit: Nathan D Costa / WTML

Uses of crack willow

Willows are prized for their slender stems which have been used for many years to weave baskets and 'cribs' for animal food. Larger stems were traditionally used to make small sailing boats.

Threats and conservation

Like other willows, crack willow is susceptible to watermark disease caused by the bacteria Brenneria salicis. Over time, this leads to affected branches dying back and red leaves developing in the crown. If left untreated, the tree can die.