Polygonum erectum

Polygonum erectum
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Caryophyllales
Family:	Polygonaceae
Genus:	Polygonum
Species:	P. erectum
Binomial name
Polygonum erectum L. 1753 not Roth 1783 nor Vell. 1827

Polygonum erectum, commonly called erect knotweed, is a North American species of herbaceous plant in the buckwheat family (Polygonaceae). It is found primarily in the northeastern and north-central parts of the United States, but with scattered populations in other parts of the US and also in Canada. ^[1]

Its natural habitat is in bottomland forests and riparian areas. It is tolerant of ecological degradation, and can also be found in disturbed open areas such as pastures and lawns. ^{[2] [3]}

It was cultivated for food by Native Americans as early as 1000 BC. Domesticated in the area of North America just west of the Appalachian Mountains, erect knotweed was part of a group of crops known as the Eastern Agricultural Complex, along with goosefoot, sunflower, sumpweed, little barley, maygrass, and squash. ^[4] These crops became the primary source of calories for many communities in North America until the gradual introduction of maize supplanted them from circa 500 AD to circa 850 AD, culminating in the Three Sisters method of farming maize, squash, and beans together circa 1050 AD. ^{[5] [6]} By 1 AD, domesticated subspecies of erect knotweed (Polygonum erectum subsp. watsoniae) was developed in the Ohio River Valley, but it has since become extinct. ^[7]

Description

Polygonum erectum is an erect annual growing 10–75 cm (4–29.5 in) tall with many to few, non-wiry branches. The leaves have distinct veins and entire edges or have jagged cut edges. The pedicels are shorter or equal the length of the calyx and typically longer than the ocreae. The closed flowers have a calyx that is typically 3 mm (0.12 in) long, green in color and 5-lobed. Flowers in clusters of 1 to 5 in cymes that are produced in the axils of most leaves. The calyx segments are unequal with the outer lobes longer and not keeled and the inner ones narrowly keeled. The tepals are greenish, with yellowish tinting or sometimes with whitish tints. The seeds are produced in fruits called achenes that can be of two different types; one type is dark brown with a shiny surface and is broadly egg-shaped, typically about 2.5 mm (0.098 in) long. The other achene type is dull brown, exsert and egg-shaped, and 3–3.5 mm (0.12–0.14 in) long. Late season fruiting is uncommon and if produced the achenes are 4 to 5 mm (0.16 to 0.20 in) long. ^{[8] [9]}

• 
  Botanical illustration of Polygonum erectum

Conservation

Polygonum erectum is considered to be globally secure. ^[10] However, it is uncommon throughout much of its range, and population have declined dramatically in some regions. ^{[2] [11]} It is listed as endangered in New Hampshire and New York. ^[12]

References

1. Kartesz, John T. (2014). "Polygonum erectum". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). Retrieved 2 June 2019.
2. Yatskievych, George (2013). Flora of Missouri, Volume 3. Missouri Botanical Garden Press. p. 746.
3. Weakley, Alan (2015). "Flora of the Southern and Mid-Atlantic States".
4. Mueller, Natalie G. (March 2018). "The earliest occurrence of a newly described domesticate in Eastern North America: Adena/Hopewell communities and agricultural innovation". Journal of Anthropological Archaeology. 49: 39–50. doi:10.1016/j.jaa.2017.12.001.
5. Bruno, Maria C. (February 25, 2019). "Indigenous American Agricultural Contributions to Modern Global Food Systems". Oxford Research Encyclopedia of Environmental Science. Oxford University Press. doi:10.1093/acrefore/9780199389414.013.176. ISBN   978-0-19-938941-4 . Retrieved 2025-10-24.
6. Mueller, Natalie G. (May 2025). "The sleeping crops of eastern North America: a new synthesis". Philosophical Transactions of the Royal Society B: Biological Sciences. 380 (1926). doi:10.1098/rstb.2024.0192. ISSN   0962-8436. PMC   12079124 . PMID   40370024.
7. Mueller, Natalie G. (2019). "Documenting the Evolution of Agrobiodiversity in the Archaeological Record: Landraces of a Newly Described Domesticate (Polygonum erectum) in North America". Journal of Archaeological Method and Theory. 26 (1): 313–343. ISSN   1072-5369.
8. Gleason, A., Henry (1963). The new Britton and Brown illustrated flora of the northeastern United States and adjacent Canada. New York Botanical Garden by Hafner Pub. Co. pp. 72–84. LCCN   63016478.
9. Flora of North America, Polygonum erectum Linnaeus, 1753. Erect knotweed, renouée dressée
10. "Polygonum erectum". NatureServe Explorer. NatureServe. Retrieved 2019-06-02.
11. "Polygonum erectum". Go Botany. New England Wildflower Society. Retrieved 2 June 2019.
12. NRCS. "Polygonum erectum". PLANTS Database. United States Department of Agriculture (USDA). Retrieved 2 June 2019.