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Any of various plants of the genera Persicaria and Polygonum, having sheathlike stipules and small, densely clustered pink, white, or green flowers.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Plants) any of several perennial aquatic plants of the genus Polygonum. Also called: water pepper
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014



any of several weeds belonging to the genus Polygonum, of the buckwheat family, that have a smarting, acrid juice.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in classic literature ?
I used to love to drift along the pale-yellow cornfields, looking for the damp spots one sometimes found at their edges, where the smartweed soon turned a rich copper colour and the narrow brown leaves hung curled like cocoons about the swollen joints of the stem.
"Let's say you have had a crop of a combination of wild millet, smartweed, and American sloughgrass that has been flooded for the winter to attract waterfowl," Rogers says.
I quickly reminded myself that the object of my admiration was a weed: smartweed. Once again, that line dividing weeds from garden plants blurred.
Polygonaceae is the family of flowering plants known as knotweed or smartweed. There are 50 genera and 1200 species in this family (Batool et al., 2015 and Mabberley, 2008).
Instead of forest floors carpeted by picturesque arrays of trout lily or bloodroot, we have dense and oppressive monocultures of the ubiquitous garlic mustard, smartweed, Asiatic dayflower and Japanese stilt grass.
L.), plantain (Plantago spp.), and horsenettle (Solanum carolinense L.), followed by grassland II that consisted mainly of orchardgrass, timothy, alfalfa (Medicago sativa L.), white and red clover, and forbs including Canada thistle (Cirsium arvense (L.) Scop.), bedstraw (Galium aparine L.), ground ivy, and dock and grassland III that consisted mainly of tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.), orchardgrass, and white and red clover along with the forbs bedstraw, plantain, ragweed (Ambrosia artemisiifolia L.), and smartweed (Polygonum pensylvanicum L.).
POLYGONACEAE (Smartweed Family) Fallopia scandens (L.) Holub--CW, SW; MWL/CB; Rare; C = 0; BSUH 19740.
As a result, in 2011 we banded at Cattail Lakes, where a limited amount of wetland vegetation dominated by smartweed (Persicaria pensylvanica) and golden-fruited dock (Rumex chrysocarpus) was used by yellowthroats.
This opens the door for mat punchin'--heavy-duty, hand-tofin combat, especially where plants include gnarly alligatorweed, smartweed, or pennywort, or heavily matted milfoil and hydrilla.
He directed my attention to the cattails and swamp smartweed and searched for some purple prairie clover, which he was determined to have me smell.
While hunting a small pothole surrounded by woods, I shot a gadwall that sailed across the water and pitched into a jungle of downed timber, dried water lily stalks and smartweed. I suspected Babe might have trouble with this one but had confidence in her so off she went.
walkeri were collected at the margin of the Lake in what the author described as "a dense smartweed swamp."