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Yavapai County Native & Naturalized Plants

Polygonum aviculare - prostrate knotweed

Synonyms: Polygonum heterophyllum, Polygonum monspeliense
Other Common Names: doorweed, knotgrass, wiregrass, yard knotweed
Plant Form: Forb or Subshrub

Family: Polygonaceae

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Watson Lake
Sue Smith
Watson Lake
Sue Smith
Plant - summer
Watson Lake
Sue Smith
Forb Plant Description

Origin: Introduced   Life Cycle: Annual
General Desc: Weedy, prostrate, mat forming plant, branching from a central point, reaching 4 to 80 inches in diameter. Flowers are inconspicuous at leaf axils.
Identification notes: Stems decumbent or prostrate with flowers scattered along the stem in axillary clusters distinguishes this from other Polygonum sp.
Height: To 15 inches


Habitat Description: Mainly in disturbed areas.
Plant Communities: Disturbed Areas
Elevation: 100 - 8500 feet

Flower Characteristics

Color: Greenish with white to pink or red margins     Shape: Inconspicuous not in clusters     Tubular: N     Flowering Period: Mar - Oct
Description: Flowers are small, 1/16 - 1/8 inch long, in leaf axils.

Leaf and Stem Characteristics

Leaf Color: Green     Leaf Type: Simple     Leaf Shape: Narrow     Leaf Margin: Smooth     Leaf Attachment: Alternate     Leaves Clasp: N
Hairs: No     Spines: N
Leaf Description: Leaves are lance-shaped to oblong, 1/2 to 2-1/2 inches long and 1/8 to 1/3 inch wide with thin papery sheaths at each node. The wiry stems are prostrate to semi-erect.

Fruit and Seed Characteristics

Fruit Color: Reddish-brown   
Fruit Type: Achene
Fruit Notes: Contains 1 seed.
Seed Notes: Seeds are 3-angled and about 1/16 inch long.

  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
(928) 445-6590
Version 8.0  
Last Updated: Nov 21, 2021
Content Questions/Comments: Email Mary Barnes  
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