Shrub · Salicaceae
Least willow
Salix rotundifolia
Least willow is recorded as native to 2 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 21 counties of those states by USDA PLANTS.
Key facts · USDA PLANTS
Least willow at a glance
- Native in
- 21 counties, across 2 states and territories
- Estimated cold hardiness
- Zone 4a PLANTS minimum temperature −30°F
- Mature height
- 2 in PLANTS mature height
- Light and water
- Not recorded Moisture use not recorded
Estimated cold hardiness: zone 4a. PLANTS gives a minimum temperature of −30°F; zone 4a winters bottom out at −30°F, the coldest half-zone that stays within that limit.
Least willow is recorded as native to 2 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 21 counties of those states by USDA PLANTS.
Counties where it is native
The 15 counties with the most ZIP codes among the 21 where it is listed.
- Yukon-Koyukuk Census Area, AK
- Bethel Census Area, AK
- Anchorage Municipality, AK
- Kenai Peninsula Borough, AK
- Lake and Peninsula Borough, AK
- Nome Census Area, AK
- Fremont County, WY
- Matanuska-Susitna Borough, AK
- Northwest Arctic Borough, AK
- North Slope Borough, AK
- Aleutians West Census Area, AK
- Southeast Fairbanks Census Area, AK
- Teton County, WY
- Kodiak Island Borough, AK
- Park County, WY
Native counties by state
Growing traits
Values from the PLANTS characteristics record. “Not recorded” means PLANTS has no value; nothing here is estimated except the zone.
Growth
- Growth habit
- Shrub, Subshrub
- Duration
- Perennial
- Mature height
- 2 in
- Growth rate
- Moderate
- Growth form
- Not recorded
- Shape
- Not recorded
- Lifespan
- Short
- Active growth period
- Not recorded
Light and water
- Shade tolerance
- Not recorded
- Moisture use
- Not recorded
- Drought tolerance
- Low
- Tolerance of waterlogged soil
- Medium
- Precipitation range
- 10 to 59 in per year
Soil
- Soil textures
- Coarse and medium
- pH range
- 5.5 to 7.5
- Lime (CaCO₃) tolerance
- Not recorded
- Salinity tolerance
- None
- Fertility requirement
- Low
- Minimum root depth
- 12 in
Climate
- Minimum temperature
- −30°F
- Estimated cold hardiness
- Zone 4a and warmer
- Minimum frost-free days
- 120
- Fire tolerance
- Medium
Flowers, leaves and fruit
- Flower color
- Purple
- Showy flowers
- No
- Bloom period
- Spring
- Foliage color
- Green
- Showy in fall
- No
- Keeps leaves
- No
- Fruit color
- Not recorded
Other
- Toxicity
- Slight
- Nitrogen fixation
- None
- Nursery availability
- Not recorded
- Family
- Salicaceae
- PLANTS symbol
- SARO2
Source & data date
- Source
- USDA NRCS PLANTS Database: county distribution records, native status and plant characteristics. CC0 (public domain dedication, per the data.gov catalog record).
- Kew’s World Checklist of Vascular Plants (WCVP): native or introduced status by state. CC BY 3.0.
- USGS US-RIIS (ver. 2.0): species listed as introduced are excluded. CC0.
- Citation
- USDA, NRCS. 2026. The PLANTS Database (https://plants.usda.gov, 11/04/2026). National Plant Data Team, Greensboro, NC USA.
- Govaerts R. (ed.) (2026). WCVP: World Checklist of Vascular Plants. Facilitated by the Royal Botanic Gardens, Kew. Data file dated 2026-06-04, http://sftp.kew.org/pub/data-repositories/WCVP/ (retrieved 2026-11-04). Paper: Govaerts R. et al. (2021) The World Checklist of Vascular Plants, a continuously updated resource for exploring global plant diversity. Scientific Data 8, 215.
- Data date
- Retrieved from PLANTS on November 4, 2026; WCVP data file dated June 4, 2026.
- Scope
- Salix rotundifolia (PLANTS symbol SARO2).
- Method
- A species is listed when it is recorded as native to the state in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in the county by USDA PLANTS. Species PLANTS labels both native and introduced are listed separately. Full method · All sources