Pennsylvania Smartweed

Persicaria pensylvanica (per-sih-KAR-ee-ah pen-sill-VAN-ee-ka)

Family: Polygonaceae Native Herbaceous

HerbaceousNative

Pennsylvania smartweed is a wildflower that can be found in a wide variety of moist, open areas ranging from fields, ditches, roadsides, swamps, prairies, fence rows, edges of marshes, lakes, and ponds and abandoned parking lots. It grows at its best in dark, loamy, moist soils. Several types of insects seek out this plant in search of nectar. This includes bees, butterflies, moths, wasps, flies, and beetles. The seeds are eaten by birds such as the cardinal, goose, mallard, and sparrow. The seeds are not fully digestible, thereby spreading the partially digested seed in bird droppings. The seeds are black, shiny flattened, almost round.

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 46 attributes.

How it fits the guild

Guild layer 4 - Herbaceous

See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Fills a similar niche Apocynum cannabinum Asclepias syriaca Pycnanthemum incanum

Full plant profile

Growing Conditions

Plant type: Annual; Native Plant; Weed; Wildflower
Life cycle: Annual
USDA zones: 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b
Light: Full sun (6 or more hours of direct sunlight a day)
Soil texture: Clay; Loam (Silt); Sand
Soil drainage: Moist | Occasionally Wet
NC region: Coastal; Mountains; Piedmont
Growth rate: Medium
Canopy layer: 4 - Herbaceous

Form & Appearance

Habit / form: Dense; Erect
Texture: Medium
Leaf color: Green
Leaf arrangement: Alternate
Leaf shape: Lanceolate
Leaf feel: Smooth
Leaf size: > 6 inches long, 1-3 inches wide
Hairs present: Yes
Leaf detail: 4" to 6" shiny leaves, sheaths without fringes, reddish joints. Some plants have small, wicked barbs on slender stems, thickened at the nodes. Tiny hairs on the margins.
Flower color: Pink; Red/Burgundy; White
Flower value: Showy
Flower form: Raceme
Flower size: 1-3 inches
Flower detail: 1" to 2" dense spike of small rose-pink flowers
Bloom time: Summer
Stem color: Green; Red/Burgundy
Stem detail: Upright, sticky, hairy stems. Around each node on the stem, a membranous sheath (ocreae) is formed. The puffed-up nodes appear red in color.

Wildlife & Ecology

Native status: Native
Origin: North America, Cuba to Hispaniola
Wildlife value: Seeds are eaten by songbirds and waterfowl. Also used for nesting.
Play value: Wildlife Food Source; Wildlife Nesting

Landscape Use

Landscape location: Naturalized Area; Rock Wall; Woodland
Landscape theme: Native Garden; Rock Garden
Design feature: Specimen
Garden tags: #NC native #drought tolerant #native garden #wildlife friendly #herb garden #wildflower #weedy

Problems & Resistance

Propagation: Seed
Fire risk: low flammability

Planted at Hunnicutt

Nobody’s planted this one yet.

📍 Add a planting 📝 Add to wish list