Polygonella articulata (Coast Jointweed)

Plant Info
Also known as: Sand Jointweed, Northern Jointweed
Genus:Polygonella
Family:Polygonaceae (Buckwheat)
Life cycle:annual
Origin:native
Habitat:sun; dry, sandy soil; prairies, barrens, dunes, banks, roadsides, railroads
Bloom season:August - September
Plant height:4 to 20 inches
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 5-petals Cluster type: raceme

[photo of flowers] Many-flowered racemes each up to 1½ inches long at the tips of branching stems. Flowers are about 1/8 inch across, with 5 spreading tepals (petals and similar sepals) that are all about the same size, white to pink, sometimes with a green or purplish midrib. In the center are 7 or 8 stamens surrounding a cone-shaped ovary with a 3-parted style at the tip. Flower stalks are slender, longer than the flower, jointed near the midpoint, ascending to spreading at flowering time, becoming nodding in fruit.

[sheathing floral bracts give a jointed appearance] At the base of the flower stalk is a sheathing bract, giving the stem a jointed or segmented appearance. All flower parts are hairless.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of leaves] Leaves are alternate, erect to ascending, hairless, very narrow, up to ¾ inch long and about as wide as the stem, often dropping off early, sometimes persisting through flowering. Stems are erect, slender and wiry, hairless, often reddish brown in the lower plant, and usually much branched with erect to ascending branches.

Fruit: Fruit type: seed without plume

[photo of fruit] The tepals persist in fruit, loosely wrapping the single seed and turning brown. Seeds are 3-sided, narrowly pyramidal, smooth and shiny cinnamon to reddish brown.

Notes:

Coast Jointweed, known in some references as Polygonum articulatum, reaches the western edge of its range in Minnesota. It's rather spindly looking when the leaves have all fallen off, but can have a profusion of white to pink blossoms that do make it stand out. It is easily identified by the “jointed” upper branches.

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More photos

Photos by K. Chayka taken at Helen Allison SNA, Anoka County, Wild River State Park, Chisago County, and Whitewater Wildlife Management Area, Winona County. Photos courtesy Peter M. Dziuk taken in Anoka County.

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