''Polygonum americanum'', commonly called southern jointweed or American jointweed, is a species of flowering plant in the knotweed family. It is native to

Southeastern United States The Southeastern United States, also known as the American Southeast or simply the Southeast, is a geographical List of regions in the United States, region of the United States located in the eastern portion of the Southern United States and t ...

extending in scattered locations west to

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

. Its preferred habitat is dry, sandy areas. ''Polygonum americanum'' was first described in 1845. It was at one time placed in the genus ''Polygonella'' (under the name ''Polygonella ''), but in 2015, following a series of

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies, this genus was subsumed into ''

Polygonum ''Polygonum'' is a genus of about 130 species of flowering plants in the buckwheat and knotweed family Polygonaceae. Common names include knotweed and knotgrass (though the common names may refer more broadly to plants from Polygonaceae). In the ...

''.

References

serotinum Flora of the Southeastern United States Flora of New Mexico Plants described in 1820 Taxa named by Constantine Samuel Rafinesque Flora without expected TNC conservation status {{Polygonaceae-stub