Plant Image
Flower spike

Yavapai County Native & Naturalized Plants

Polygonum lapathifolium - curlytop knotweed

Synonyms: Persicaria lapathifolia, Persicaria incarnata , Persicaria tomentosa, Polygonum incanum, Polygonum incarnatum
Other Common Names: pale smartweed, willowweed
Plant Form: Forb or Subshrub

Family: Polygonaceae

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Patrick Alexander @, Usage Rights: Creative Commons Attribution-ShareAlike (CC BY-SA)
Patrick Alexander @, Usage Rights: Creative Commons Attribution-ShareAlike (CC BY-SA)
Forb Plant Description

Origin: Native   Life Cycle: Annual
General Desc: An upright, branched, willowy-looking summer annual. It is a broadleaf plant that typically inhabits areas in or around water.
Identification notes: Nodding or drooping inflorescence; sheaths without marginal bristles; auxilary and terminal inflorescence; bracts of inflorescence reduced to sheaths; stems not twining.
Height: 2 to 5 feet


Habitat Description: Wet soils and floodplains. Also waste spaces, roadsides, and cultivated fields.
Plant Communities: Riparian, Disturbed Areas
Elevation: 1000 - 6000 feet

Flower Characteristics

Color: Greenish-white to pink     Shape: Bell-shaped in elongated clusters     Tubular: Y     Flowering Period: Apr - Oct
Description: Clusters are dense, drooping and arching. The individual flowers remain closed.

Leaf and Stem Characteristics

Leaf Color: Green     Leaf Type: Simple     Leaf Shape: Narrow     Leaf Margin: Smooth     Leaf Attachment: Alternate     Leaves Clasp: N
Hairs: Leaves     Spines: N
Leaf Description: Stems are erect, branched and usually swollen and sheathed at the leaf node. Tapered tip leaves are sometimes marked with a dark blotch.

Fruit and Seed Characteristics

Fruit Color: Brown   
Fruit Type: Achene
Seed Notes: Seeds are shiny, flattened and indented on both sides.

  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
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Version 8.0  
Last Updated: Dec 13, 2022
Content Questions/Comments: Email Matt Halldorson  
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