# Crack willow (Salix × fragilis)

> A broad, fast-growing willow to 25 m whose brittle twigs snap with an audible crack and root wherever they wash up, so a single tree can colonise a whole river. In Britain it is a familiar pollarded riverside tree. In New Zealand and Australia it chokes waterways, diverts flow, drops leaves that deoxygenate streams and displaces native riparian trees: it is banned from sale, propagation and distribution under the NZ National Pest Plant Accord 2020 and is a Weed of National Significance declared in every Australian state.

Source: https://treerm.org/trees/salix-x-fragilis · Updated 2026-11-08 · License CC BY 4.0

## Facts

- Also called: Brittle willow
- Family: Salicaceae
- Type: Broadleaf, loses its leaves in winter
- Mature height: 20 m; spread 15 m
- Growth: Fast growing; lives about 80 years
- Light: Full sun
- Water: Needs steady water
- Soil: Wet riverbanks, lake margins and floodplains; any moist soil
- Native range: A hybrid willow of European and western Asian origin (POWO treats it as Salix × fragilis, S. alba × S. euxina, native to Türkiye and adjacent regions); widely planted and naturalised across Europe, North America, Australia and New Zealand.

**Benefits:** Holds soil, Flood tolerant, Fast canopy, Pollinators

**Good for:** Streambanks

**Watch out for:** Invasive elsewhere, Weak wood, Large roots

## Care

Do not plant in New Zealand or Australia; in its naturalised European range pollard every 5 to 15 years in winter to keep it safe. Control is by cut-and-paint or stem injection of herbicide, leaving dead trees standing a year before removal so banks do not collapse; broken twigs re-root, so bag and remove them. Replace with local native riparian species.

## Where it stands

- **Native:** Türkiye (WCVP records the hybrid as native to Türkiye)
- **Adapted:** Germany (Introduced per WCVP); United Kingdom (Long naturalised and planted along rivers; introduced per WCVP)
- **Prohibited:** NSW, Australia (Willows (except weeping, pussy and sterile pussy willow) are a Weed of National Significance declared in all states and territories); SA, Australia (Weed of National Significance; declared); TAS, Australia (Weed of National Significance; declared); VIC, Australia (Weed of National Significance; declared); New Zealand (Listed in the 2020 National Pest Plant Accord: an unwanted organism banned from sale, propagation and distribution; also on DOC's 2024 list of environmental weeds)

## Sources

- https://www.nzpcn.org.nz/flora/species/salix-xfragilis/
- https://weeds.org.au/weeds-profiles/
- https://weeds.org.au/profiles/willows-except-weeping/
- https://www.gbif.org/species/5372829