Polygonum hydropiperoides Michx.

vernacular swamp smartweed — species · Polygonaceae

USDA: POHY2
GBIF: 8147126
Rank: species

swamp smartweed (Polygonum hydropiperoides) — Platephotograph · Sam Wahl source · iNaturalist ↗

§2Habit & range

Growth habit: Forb/herb
Duration: Perennial
Group: Dicot
Family: Polygonaceae Juss.
Genus: Polygonum

§2a

Native status, by region

AK Alaska Introduced
CAN Canada Native
L48 Lower 48 States Native
PR Puerto Rico Native

§2b

County-level range

· 4 counties across 1 state

Legend Native · 4 Introduced · 0 Both · 0 Hover a county for detail.

§3Cultivation specs · USDA

Recorded by the USDA Plant Materials Program.

§3a

Tolerances

Drought: Low
Shade: High
Moisture use: Medium
Fire: Medium
Salinity: Low
Anaerobic: High
CaCO₃: High
Hedging: None

§3b

Climate & soil

Cold tolerance: 32 °F minimum
Frost-free days: 95 min.
Precipitation: 12–50 in/yr
pH range: 4.5–8.8
Root depth: 10 in min.
Fertility need: Medium
Soil texture: medium, fine

§3c

Form & growth

Growth form: Single Crown
Growth rate: Slow
Lifespan: Moderate
Foliage texture: Fine
Foliage colour: Dark Green
Porosity (summer): Porous
Porosity (winter): Porous
Flower colour: Green
Fruit colour: Green
Fire resistant: No
N fixation: None
Toxicity: None

§3d

Reproduction

Bloom period: Indeterminate
Seed abundance: Medium
Seed begins: Spring
Seed ends: Summer
Spread rate: Moderate
Stratify: No
Seeds / lb: 612,963
Propagation: seed

§3e

Use & availability

Commercial availability: Routinely Available
Nursery stock: No
Browse palatability: Low
Palatable, human: No
Lumber: No
Christmas tree: No

§4Counties, by state

Recorded in 4 counties across 1 state.

Rhode Island view state ↗ 4 N ▾

§5Sources & provenance

USDA PLANTS

Symbol, taxonomy, distribution, cultivation specs, native status. Public domain.

plants.usda.gov/POHY2 ↗

GBIF Backbone

Canonical taxonomic identity, synonym resolution, cross-refs. CC0.

gbif.org/species/8147126 ↗

Record version

Cached and built locally. Source version on this record:

usda-plants-mt-2026-05-25

fetched 2026-05-25T18:27:19Z