Swamp Smartweed (Persicaria hydropiperoides) Has Pinkish White Flowers

Summary: Swamp smartweed (Persicaria hydropiperoides), a widespread New World native perennial, has pinkish white flowers and long, narrow green leaves.

Closeup of swamp smartweed (Persicaria hydropiperoides; syn. Polygonum hydropiperoides) flowers: Robert H. Mohlenbrock/USDA NRCS Wetland Science Institute (WSI), Public Domain, via USDA NRCS (Natural Resources Conservation Service) PLANTS Database

Swamp smartweed (Persicaria hydropiperoides) is a widespread Old World native perennial with pinkish white flowers and long, narrow green leaves.

Persicaria hydropiperoides is known commonly as swamp smartweed. Other common names include false water-pepper smartweed, marsh-pepper smartweed, mild smartweed and mild water-pepper.

Swamp smartweed claims New World homelands spanning North America, Central America and South America. In Northern America, swamp smartweed is native to all but three (Colorado, Utah, Wyoming) of the United States’ Lower 48. Swamp smartweed is native to Puerto Rico but does not occur natively in Alaska, Hawaii or the U.S. Virgin Islands.

Native distribution occurs in half (British Columbia, New Brunswick, Nova Scotia, Ontario, Quebec) of Canada’s 10 provinces. Swamp smartweed is not native to any of Canada’s three territories.

Swamp smartweed’s native occurrence in South America includes not only most of the continent but also the Galápagos Islands. The Pacific Ocean archipelago is Ecuador’s only overseas province.

Great variability across swamp smartweed’s extensive New World range accounts for a lengthy list of scientific synonyms. French botanist and explorer André Michaux (March 7, 1746-Oct. 11, 1802) is responsible for the Old World’s first description of swamp smartweed. His choice of Polygonum hydropiperoides reflects the perennial’s display of ensheathed nodes, a characteristic of the Polygonum genus (Ancient Greek: πολύς, polús, “many” + γόνυ, gónu, “joint, knee”), and also its similarity to water pepper (Persicaria hydropiper; syn. Polygonum hydropiper).

A former synonym, Persicaria hydropiperoides, is now swamp smartweed’s accepted scientific name. The change in genus recognizes the resemblance of smartweed species’ leaves to those of peach trees (Latin: persicum, “peach, Persian fruit”). This scientific name traces back to American botanist John Kunkel Small (Jan. 31, 1869-Jan. 20, 1938) in 1903.

Swamp smartweed thrives in moist to wet habitats. Sunlight requirements range from full sun to partial shade. Swamp smartweed is found in shallow water, muddy soils and wet gravelly and/or sandy soils. Preferred habitats include marshes, pond edges, moist prairies, roadside ditches, wet banks and clearings, and wet woods.

Multiple stems arise from a rhizomatous (Ancient Greek: ῥίζα, rhíza, “root”) root system. Light green stems, which may remain erect or sprawl, measure 2 to 3 feet (0.6 to 0.91 meters).

Green to dark green leaves appear alternately along stems. Leaf blades tend to lack the dark crescent or triangular blotches associated with other smartweed species. Unindented leaf margins, which are unlobed and untoothed, are known as entire.

Linear-lanceolate (Latin: lanceolatus, “lance-shaped”) leaves are long and narrow. Leaf length may range from around 2 inches to over 9 inches (5 to 25 centimeters). Leaf width may measure one-fourth of an inch to almost 1.5 inches (0.4 to 3.7 centimeters).

Petioles, the stalks attaching leaf blades to stems, are diminutive. Petiole length ranges from seven one-hundredths of an inch to about three-fourths of an inch (0.2 to 2 centimeters).

Swamp smartweed stems feature the nodal sheaths, known as ocreas (Latin: ocrea, “legging”), that characterize the Polygonaceae family’s type genus of Polygonum. The sheaths wrap around nodes, points of attachment to stems. Brownish-colored ocreas are surfaced with cilia, stiff hairlike structures.

Various growing conditions and light levels account for a potentially long blooming period. Flowers may open as early as June and last into the autumn months of October or November.

Flowers comprise tepals, or undifferentiated sepals and petals, which form a cup with their fused bases. The diameter of the tiny five-parted flower is about one-eighth of an inch (3 millimeters).

Tiny pinkish, greenish whitish or whitish flowers are loosely displayed in spike-like racemes (Latin: racemus, “cluster of grapes”) that extend usually terminally, at stem tops. Occasionally axillary racemes emerge from upper axils, junctions of leaves and stems.

Swamp smartweed’s fruit is a dry, single-seeded capsule known as an achene (Ancient Greek: ἀ-, a-, “not” + χαίνω, khaínō, “to gape”). The shiny, smooth, three-sided capsule is colored brown, brownish black or black.

Persicaria hydropiperoides plants attest to the appealing variability of smartweed wildflowers. Swamp smartweed’s occurrence in moist or wet habitats guarantees a pleasing blend of tiny pinkish white flowers with long, slender green leaves.

Swamp smartweed (Persicaria hydropiperoides; syn. Polygonum hydropiperoides), Humboldt Bay National Wildlife Refuge, California North Coast: Gordon Leppig and Andrea J. Pickart/US Fish and Wildlife Service, Public Domain, via Wikimedia Commons

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Closeup of swamp smartweed (Persicaria hydropiperoides; syn. Polygonum hydropiperoides) flowers: Robert H. Mohlenbrock/USDA NRCS Wetland Science Institute (WSI), Public Domain, via USDA NRCS (Natural Resources Conservation Service) PLANTS Database @ http://plants.usda.gov/java/largeImage?imageID=pohy2_002_ahp.tif

Swamp smartweed (Persicaria hydropiperoides; syn. Polygonum hydropiperoides), Humboldt Bay National Wildlife Refuge, California North Coast: Gordon Leppig and Andrea J. Pickart/US Fish and Wildlife Service, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Polygonumhydropiperoides.jpg

For further information:

Chayka, Katy. “Persicaria hydropiperoides (Mild Waterpepper).” Minnesota Wildflowers.
Available @ https://www.minnesotawildflowers.info/flower/mild-waterpepper

Maiz-Tome, L. “Persicaria hydropiperoides.” IUCN Red List of Threatened Species.
Available @ http://www.iucnredlist.org/details/64320296/0

Marriner, Derdriu. “Jumpseed (Persicaria virginiana) Has Tiny White Flowers and Big Green Leaves.” Earth and Space News. Saturday, June 25, 2016.
Available @ https://earth-and-space-news.blogspot.com/2016/06/jumpseed-persicaria-virginiana-has-tiny.html

Marriner, Derdriu. “Pennsylvania Smartweed (Persicaria pensylvanica) Has Tiny Pink Flowers.” Earth and Space News. Sunday, June 19, 2016.
Available @ https://earth-and-space-news.blogspot.com/2016/06/pennsylvania-smartweed-persicaria.html

“Mild Waterpepper Persicaria hydropiperoides.” Illinois Wildflowers > Wetland Wildflowers.
Available @ http://www.illinoiswildflowers.info/wetland/plants/mild_wtpepper.htm

Mohlenbrock, Robert H. Northeast Wetland Flora: Field Office Guide to Plant Species. Chester PA: USDA NRCS (Natural Resources Conservation Service) Northeast National Technical Center, 1995.

“Persicaria hydropiperoides (Michaux) Small.” Canadensys VASCAN (Vascular Plants of Canada Database) > Taxon.
Available @ http://data.canadensys.net/vascan/taxon/8145

“Persicaria hydropiperoides (Michaux) Small.” eFloras > Flora of North America > Flora Taxon.
Available @ http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250037826

“Persicaria hydropiperoides (Michx.) Small.” Digital Atlas of the Virginia Flora.
Available @ http://vaplantatlas.org/index.php?do=plant&plant=3226&search=Search

“Persicaria hydropiperoides (Michx.) Small False Water-Pepper Smartweed.” New England Wildflower Society Go Botany > Simple Key.
Available @ https://gobotany.newenglandwild.org/species/persicaria/hydropiperoides/

“Persicaria hydropiperoides Swamp Smartweed.” Encyclopedia of Life.
Available @ http://eol.org/pages/586678/hierarchy_entries/46190265/details

“Polygonum hydropiperoides Michx. Swamp Smartweed.” USDA NRCS (Natural Resources Conservation Service) PLANTS Database.
Available @ http://plants.usda.gov/core/profile?symbol=POHY2

Tenaglia, Dan. “Polygonum hydropiperoides Michx.” Missouri Plants > White Flowers, Alternate Leaves.
Available @ http://www.missouriplants.com/Whitealt/Polygonum_hydropiperoides_page.html