Wildflower (forb) · Lamiaceae
American water horehound
Lycopus americanus
American water horehound is recorded as native to 47 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 1,333 counties of those states by USDA PLANTS.
Key facts · USDA PLANTS
American water horehound at a glance
- Native in
- 1,333 counties, across 47 states and territories
- Estimated cold hardiness
- Zone 3b PLANTS minimum temperature −38°F
- Mature height
- 1.8 ft PLANTS mature height
- Light and water
- Tolerates shade High water use
Estimated cold hardiness: zone 3b. PLANTS gives a minimum temperature of −38°F; zone 3b winters bottom out at −35°F, the coldest half-zone that stays within that limit.
American water horehound is recorded as native to 47 states and territories in Kew’s World Checklist of Vascular Plants and USDA PLANTS, and recorded in 1,333 counties of those states by USDA PLANTS.
Counties where it is native
The 15 counties with the most ZIP codes among the 1,333 where it is listed.
Native counties by state
- Alabama 4 counties
- Arizona 2 counties
- Arkansas 9 counties
- California 26 counties
- Colorado 16 counties
- Connecticut statewide record
- Delaware 2 counties
- District of Columbia 1 county
- Florida 1 county
- Idaho 12 counties
- Illinois 102 counties
- Indiana 75 counties
- Iowa 17 counties
- Kansas 78 counties
- Kentucky 47 counties
- Louisiana 13 counties
- Maine 16 counties
- Maryland 1 county
- Massachusetts 14 counties
- Michigan 77 counties
- Minnesota 74 counties
- Mississippi 5 counties
- Missouri 86 counties
- Montana 7 counties
- Nebraska 53 counties
- New Hampshire 10 counties
- New Jersey 18 counties
- New Mexico 8 counties
- New York 46 counties
- North Carolina 10 counties
- North Dakota 41 counties
- Ohio 84 counties
- Oklahoma 23 counties
- Oregon 12 counties
- Pennsylvania 67 counties
- Rhode Island 4 counties
- South Carolina 1 county
- South Dakota 22 counties
- Tennessee 30 counties
- Texas 17 counties
- Utah 7 counties
- Vermont 13 counties
- Virginia 69 counties
- Washington 16 counties
- West Virginia 25 counties
- Wisconsin 62 counties
- Wyoming 10 counties
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
- Forb/herb
- Duration
- Perennial
- Mature height
- 1.8 ft
- Growth rate
- Moderate
- Growth form
- Single Crown
- Shape
- Erect
- Lifespan
- Long
- Active growth period
- Summer and Fall
Light and water
- Shade tolerance
- Tolerant (tolerates shade)
- Moisture use
- High water use
- Drought tolerance
- Low
- Tolerance of waterlogged soil
- High
- Precipitation range
- 12 to 60 in per year
Soil
- Soil textures
- Medium and fine
- pH range
- 5.2 to 7.8
- Lime (CaCO₃) tolerance
- Medium
- Salinity tolerance
- Low
- Fertility requirement
- Medium
- Minimum root depth
- 10 in
Climate
- Minimum temperature
- −38°F
- Estimated cold hardiness
- Zone 3b and warmer
- Minimum frost-free days
- 120
- Fire tolerance
- High
Flowers, leaves and fruit
- Flower color
- White
- Showy flowers
- No
- Bloom period
- Early Summer
- Foliage color
- Green
- Showy in fall
- No
- Keeps leaves
- No
- Fruit color
- Brown
Other
- Toxicity
- None
- Nitrogen fixation
- None
- Nursery availability
- Routinely Available
- Family
- Lamiaceae
- PLANTS symbol
- LYAM
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
- Lycopus americanus (PLANTS symbol LYAM).
- 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