Polygonum arenastrum
species of summer annual weed
Polygonum arenastrum, commonly known as equal-leaved knotgrass, is a summer annual flowering plant in the knotweed family Polygonaceae. Other common names include common knotweed, prostrate knotweed, mat grass, oval-leaf knotweed, stone grass, wiregrass, and door weed, as well as many others. It is native to Eurasia and can be found on other continents as an introduced species and a common noxious weed. Knotweed was first seen in North America in 1809 and is now seen across much of the United States and Canada.
Description
Knotweed develops a deep tap root (it can be as deep as 18 in (46 cm)), does well in compacted soil, and survives drought conditions. The numerous wiry stems grow out from the center of the plant giving it a mat-like appearance. The stems are very long and branching and grow in a zigzag form. The leaves are alternate, oblong, hairless, can be 1⁄2 to 2+1⁄2 inches (12 to 37 mm) long, and are bluish-green in color. The leaf stalk is short and closely surrounded by papery stipules on each node. The stem nodes are slightly swollen and look somewhat like "knots", thus its common name, knotweed.
The public source identifies “Polygonum arenastrum” as species of summer annual weed. This brief keeps that definition visible, then builds a research path around Polygonum, arenastrum and species.
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A short description can identify a subject without explaining its stakes. For “Polygonum arenastrum”, the useful work is to connect “species of summer annual weed” to the records capable of establishing context and consequence.
Datasets, specimens, observations and peer-reviewed methods provide the appropriate test for the technical claims summarized here. The source revision retrieved here is dated Aug 25, 2026. The linked authority identifier is Q4280447. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1809.
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This entry incorporates text from “Polygonum arenastrum” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.