E-Flora BC: Electronic Atlas of the Flora of British Columbia

Polygonum polygaloides subsp. confertiflorum Wall. ex Meisn. (Nutt. ex Piper) J.C. Hickman
close-flowered knotweed (fruitleaf knotweed)
Polygonaceae (Buckwheat family)

Introduction to Vascular Plants

© Ryan Batten  Email the photographer   (Photo ID #67075)

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Distribution of Polygonum polygaloides subsp. confertiflorum
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Species Information

Annual herb from a taproot; stems erect or ascending, solitary, usually freely branched, smooth, angled, 1-15 cm tall.
Basal leaves lacking; stem leaves alternate, linear, the blades 10-40 mm long, unstalked; stipules ragged, 4-8 mm long.
Inflorescence a terminal, spikelike raceme, closely crowded and usually overlapping, in groups of 1-4 in the axils of white- or green-margined floral bracts; perianths 2-3 mm long, white to red, unequally 5-lobed 2/3 the distance to the base.
Achenes 3-angled, brown to nearly black, dull or shiny, smooth or longitudinally lined, 1.5-2 mm long, sometimes difficult to separate.
Two subspecies occur in our region.

1. Floral bract margins white; achenes brown to nearly black; usually dull, longitudinally grooved......................... ssp. confertiflorum (Piper) Hickman

1. Floral bract margins green; achenes brown, usually shiny, smooth......................... ssp. kelloggii (Greene) Hickman

Source: The Illustrated Flora of British Columbia

Habitat / Range

Wet vernal pools and ditches to dry roadsides and meadows in the montane and subalpine zones; ssp. confertiflorum - rare in SC BC, ssp. kelloggii Greene - rare in S BC; E to SW AB and S to CO, AZ and CA.

Source: The Illustrated Flora of British Columbia


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Polygonum confertiflorum Nutt. ex Piper
Polygonum imbricatum Nutt.
Polygonum kelloggii var. confertiflorum (Nutt. ex Piper) Dorn
Polygonum watsonii Small

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References