Plant Image
Flower spike

Yavapai County Native & Naturalized Plants

Polygonum pensylvanicum - Pennsylvania smartweed

Synonyms: Persicaria pensylvanica, Persicaria bicornis, Persicaria longistyla, Polygonum mexicanum
Other Common Names: pinkweed
Plant Form: Forb

Family: Polygonaceae

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Leaves and flowers
Max Licher @
Max Licher @
Forb Plant Description

Origin: Native   Life Cycle: Annual
General Desc: This plant is more or less erect, branching occasionally and often bending toward the light in partially shaded locations.
Identification notes: Leaves have few or no hairs, upper stems and flower stems with usually red glands; stipules at base of the leaves cylindric without hairs; calyx (sepals) bright pink; inflorescences erect, in leaf axils and terminal, flower bracts reduced to sheaths.
Height: 1 to 4 feet


Habitat Description: Moist, disturbed places, ditches, riverbanks, cultivated fields, shorelines of ponds and reservoirs.
Plant Communities: Riparian, Disturbed Areas
Elevation: 2500 - 7000 feet

Flower Characteristics

Color: Pink     Shape: Irregular in elongated clusters     Tubular: N     Flowering Period: May - Dec
Description: Dense, erect, spike-like clusters of small, bright pink flowers are borne on sticky-haired stalks.

Leaf and Stem Characteristics

Leaf Color: Green     Leaf Type: Simple     Leaf Shape: Narrow     Leaf Margin: Smooth     Leaf Attachment: Alternate     Leaves Clasp: N
Hairs: Leaves and stems     Spines: N
Leaf Description: Leaves have membranous sheaths at the bases of the leaf stalks that surround the stems. Smooth round stems are light green to red and relatively stout; they have a tendency to zigzag between the alternate leaves.

Fruit and Seed Characteristics

Fruit Color: Brown   
Fruit Type: Achene
Fruit Notes: Fruits are round in outline, generally nearly flat on 1 side, indented on other, dark brown and shiny.

  Arizona Cooperative Extension
Yavapai County
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Last Updated: Feb 16, 2020  
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