Persicaria punctata (dotted smartweed)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Biology and Ecology
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Distribution Maps
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IdentityTop of page
Preferred Scientific Name
- Persicaria punctata (Elliott) Small
Preferred Common Name
- dotted smartweed
Other Scientific Names
- Persicaria persicarioides (Kunth) Small
- Persicaria punctate var. eciliata Small
- Polygonum acre Kunth
- Polygonum epilobioides Wedd.
- Polygonum punctatum Elliot
- Polygonum punctatum var. aquatile (Mart.) Fassett
- Polygonum punctatum var. confertiflorum (Meisn.) Fassett
- Polygonum punctatum var. ellipticum Fassett
- Polygonum punctatum var. leptostachyum (Meisn.) Small
- Polygonum punctatum var. parviflorum Fassett
- Polygonum punctatum var. parvum Vict. & J. Rousseau
- Polygonum punctatum var. punctatum Elliott
Local Common Names
- : ananash; barbasco; hierba del bicho; padilla; yerba caiman; yerba de sap
- : arse-smart; tar-weed; turkey-troop; water smartweed
- : piment-vache; renouee ponctuee
- Brazil: erva-de-bicho-pontuada
Summary of InvasivenessTop of page
P. persicaria is a species of knotweed native to the Americas. It has been introduced, presumably accidentally, to New Zealand, Pakistan and Hawaii, where it is found in shallow water, shores, marshes, swamps, the borders of ponds and small streams, drainage ditches and floodplain forests.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Polygonales
- Family: Polygonaceae
- Genus: Persicaria
- Species: Persicaria punctata
Notes on Taxonomy and NomenclatureTop of page
Missouri Botanical Garden (2014) listed three varieties: Persicaria punctata var. robustior (Small) Small, Persicaria punctata var. eciliata Small and Persicaria punctata var. tacubayana Nieuwl.
Fassett (1949) proposed a complicated classification for Persicaria punctata comprising 12 varieties in North and South America. He also identified numerous specimens that he considered to be morphologically intermediate between various varieties. Dalci (1972, cited in Flora of North America, 2013) documented a wide range of phenotypic and genotypic variation throughout the range of P. punctata and extensive overlap in many of the features used by Fassett to distinguish varieties. Consequently, recognition of varieties does not seem warranted (Flora of North America, 2013).
DescriptionTop of page
Slightly modified from Flora of North America (2013):
Plants are annual or perennial, 15-120 cm; roots also often arising from proximal nodes; rhizomes often present.
Stems are ascending to erect, branched, without noticeable ribs, glabrous, glandular-punctata.
Leaves are ochre brown, cylindric, (4-)9-18 mm, chartaceous, base inflated, margins truncate, ciliate with bristles 2-11 mm, surface glabrous or strigose, glandular-punctata; petiole 0.1-1 cm, glandular-punctata, leaves sometimes sessile; blade without dark triangular or lunate blotch adaxially, lanceolate to lanceolate-ovate or subrhombic, 4-10(-15) by 0.6-2.4 cm, base tapered or cuneate, margins antrorsely strigose, apex acute to acuminate, faces glabrous or scabrous along midveins, glandular-punctata.
Inflorescences are mostly terminal, sometimes also axillary, erect, interrupted, 50-200 by 4-8 mm; peduncle 30-60 mm, glabrous, glandular-punctata; ocreolae mostly not overlapping, margins mostly ciliate with bristles to 2 mm. Pedicels ascending, 1-4 mm.
Flowers 2-6 per ocreate fascicle, homostylous; perianth greenish proximally, white distally, rarely tinged pink, glandular-punctata with punctae ± uniformly distributed, scarcely accrescent; tepals 5, connate ca. 1/ 3 their length, obovate, 3-3.5 mm, veins prominent or not, not anchor-shaped, margins entire, apex obtuse to rounded; stamens 6-8, included; anthers pink or red, elliptic to ovate; styles 2-3, connate proximally.
Achenes included or apex exerted, brownish black, usually 3-gonous, rarely biconvex, (1.8-)2.2-3.2 by 1.5-2.2 mm, shiny, smooth.
Plant TypeTop of page Annual
DistributionTop of page
P. punctata is native to most of the Americas, from Canada to Chile and including the Caribbean. It is found in all but 13 of the mainland US states and in most Canadian provinces. It is also native to many South and Central American countries. In Illinois, it is described by Illinois Wildflowers (2013) as one of the more common smartweeds in wetland areas.
P. punctata has been introduced to New Zealand, Pakistan and Hawaii, where it is found in shallow water, shores, marshes, swamps, the borders of ponds and small streams, drainage ditches and floodplain forests.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 10 Jan 2020
History of Introduction and SpreadTop of page
There is little or no information on how P. punctata was introduced to New Zealand and Pakistan. The first record of it in New Zealand was in 1976 (Webb et al., 1988).
HabitatTop of page
P. punctata grows in shallow water, shores, marshes, swamps, the borders of ponds and small streams, drainage ditches and floodplain forests (Illinois Wildflowers, 2013). This plant is often found along the edge of stagnant or slow-moving water, and appears to favour degraded wetlands. It grows at altitudes of 0-1500 m above sea level (Flora of North America, 2013). In Illinois, USA, P. punctata occurring in flood-prone areas of woodlands. In New Zealand, it is found in wet places such as swamps, ditches, lakesides and streamsides (Webb et al, 2013); similarly, in Hawaii it is found ‘naturalized along streambeds, wet areas, in running or standing water, and in disturbed wet forest’ (Wagner et al., 1999, cited in PIER, 2013).
Biology and EcologyTop of page
Little has been reported on the biology or ecology of P. punctata, but the species is similar in appearance and habitat to the cosmopolitan species P. hydropiper, whose biology may be similar.
2n = 44 (Flora of North America, 2013).
In North America P. punctata is described by Flora of North America (2013) as annual or perennial, but there seems to be no information on how long plants can live for.
In the United States, P. punctata flowers between June and November (Flora of North America, 2013).
Population size and structure
Illinois wildflowers (2013) reported that P. persicata ‘often forms colonies of varying size in wet areas’.
According to Illinois Wildflowers (2013), short-tongued Halictid bees, various kinds of wasps, Syrphid flies and other kinds of flies, and the occasional beetle, including ladybirds, are attracted to the nectar of P. punctata. Halictid bees also collect pollen.
P. punctata seems to require moist soil or even shallow standing water (Flora of North America, 2013).
Notes on Natural EnemiesTop of page
At least in Illinois, USA, caterpillars of the butterflies Lycaena hyllus (bronze copper) and Lycaena helloides (purple copper) feed on the foliage, as do the caterpillars of several moth species and the adults of the leaf beetle Gastrophysa polygoni (Illinois Wildflowers, 2013). The same source lists the larvae of the moths Lithocodia carneola, L. synochitis, Orthonoma centrostrigaria, O. obstipata, Acronicta oblinita, Pyrrhia experimens, Dipteryia rosmani, Xanthotype sospeta, Haematopis grataria and Nomophila neararctica as herbivores that feed on the foliage of Persicaria species.
Means of Movement and DispersalTop of page
Natural dispersal (non-biotic)
P. punctata has no means of vegetative spread and the seeds are not adapted for dispersal other than by floating in water.
Vector transmission (biotic)
The seeds may be transported by mud on the feet of water birds, or possibly scattered by birds feeding on the seeds.
Presumably its introductions to countries well outside its native range were accidental, so further accidental introductions are always possible.
ImpactTop of page
In the countries to which it has been introduced P. punctata seems to have had little impact so far, and is seen simply as another the introduced weedy species in wetland areas.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Has a broad native range
- Tolerant of shade
- Fast growing
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Has high genetic variability
UsesTop of page
The Chippewa, Houma, and Iroquois people of North America prepared decoctions from the leaves, flowers and roots of P. punctata for use as analgesics as well as gastrointestinal, orthopedic and psychological aids (Moerman, 1998, cited in Flora of North America, 2013).
In parts of Brazil the plant is used as a herb to treat intestinal disorders. De Almeida Alves et al. (2001) extracted the compound polygodial from aerial parts of the plant and found that it had strong fungitoxic activity. Since this compound also has antibiotic, anti-inflammatory and anti-hyperalgesic properties, it may account for the effects attributed to this species by folk medicine.
The seeds are eaten by many species of ducks, seed-eating rails and various songbirds, and may be a minor source of food to muskrats (Illinois Wildflowers, 2013). According to Hickman (2013), the species is planted as waterfowl food.
Similarities to Other Species/ConditionsTop of page
P. punctata and its close relatives P. robustior and P. glabra are unique among native North American smartweeds in possessing complex glands called valvate chambers in their epidermises.
P. punctata is confused most often with P. hydropiper (Flora of North America, 2013). Fassett (1949) noted that P. punctata shares with P. hydropiper the characteristic features of glandular dots on the perianth. However, P. punctata has smooth and shining rather than roughened and dull achenes and a strong tendency to longer internodes, less drooping spikes and less red colouring in the perianth.
Webb et al. (1988) experienced some slight difficulties with identifying the New Zealand material of P. punctata: ‘Characters of the New Zealand plants put them closer to P. punctata than any other species, judging from descriptions in eFloras and from specimens. However, in the few American specimens examined, the fruits are smooth instead of being finely granular as in New Zealand plants, although they are more or less glossy in both cases. Otherwise, the tallness and robustness of the New Zealand plants mean that they also resemble descriptions of the American P. robustius (small) fern. Both species are related to the Old World P. hydropiper. Within New Zealand, North Island plants have deep green leaves, whereas South Island plants have yellowish green leaves, but the greater size of vegetative parts still distinguishes them all from P. hydropiper. Also, the only moderately peppery taste, the more or less tubular and appressed upper ochreae, white perianth, and obviously shining fruits usually distinguish P. punctatum from P. hydropiper.’
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Individual plants of P. punctata could be pulled or dug up, but this would not be recommended for large areas.
The caterpillars of several moth species feed on Persicaria species in its native North America (see Notes on Natural Enemies; Illinois Wildflowers, 2013). However, P. punctata has not become a serious enough weed in its introduced range to warrant biological control yet.
Species of Persicaria can be controlled with glyphosate, 2,4-D, aminopyralid, clopyralid, dicamba, triclopyr or imazapyr, but all these compounds will adversely affect other plant species, including desirable species (DiTomaso et al., 2013).
Gaps in Knowledge/Research NeedsTop of page
There seems to be very little published information on the biology, ecology and associated species of P. punctata. More information on longevity of plants and seeds, environmental preferences and reproduction would be very useful.
ReferencesTop of page
Dalci M, 1972. The taxonomy of section Persicaria (Tourn. in the genus Polygonum (Tourn. (Polygonaceae) in the United States east of the Rocky Mountains. dissertation. Nebraska, USA: University of Nebraska.
DiTomaso JM; Kyser GB, 2013. Lady's thumb and pale smartweed. Weed control in natural areas in the western United States. California, USA: Weed Research and Information Centre, University of California, 544 pp. http://wric.ucdavis.edu/information/natural%20areas/wr_P/Polygonum_lapathifolium-persicaria.pdf
Fassett NC, 1949. The variation of Polygonum punctatum. Brittonia, 6(4):369-393.
Flora of North America, 2013. Flora of North America. FNA. http://www.efloras.org/flora_page.aspx?flora_id=1
Flora of Pakistan Editorial Committee, 2013. Flora of Pakistan, eFloras website. St. Louis, Missouri and Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria. http://www.efloras.org/flora_page.aspx?flora_id=5
GBIF, 2015. Global Biodiversity Information Facility. http://www.gbif.org/species
Hickman JC, 2013. Polygonaceae: Buckwheat Family. Treatment from the Jepson Manual. http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment
Homeopathic Materia Medica, 2013. Polygonum punctatum. International Academy of Classical Homeopathy. http://www.vithoulkas.com/en/component/content/article/240-materia-medica-by-boericke/3741-polygonum-punctatum.html
Illinois Wildflowers, 2013. Water Smartweed: Persicaria punctate. Wetland Wildflowers. http://www.illinoiswildflowers.info/wetland/plants/water_smartweed.htm
Invasiveorg, 2013. Dotted smartweed: Persicaria punctata (Ell.) Small. Invasive and Exotic Species of North America. http://www.invasive.org/browse/subinfo.cfm?sub=14141
ITIS, 2013. Integrated Taxonomic Information System (ITIS). Washington, DC, USA: Smithsonian Institution/NMNH. http://www.itis.gov/
Missouri Botanical Garden, 2014. Tropicos database. St. Louis, Missouri, USA: Missouri Botanical Garden. http://www.tropicos.org/
New Zealand History online, 2012. US forces in New Zealand. http://www.nzhistory.net.nz/war/us-forces-in-new-zealand
PIER, 2013. Pacific Islands Ecosystems at Risk. Honolulu, Hawaii, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html
Swearingen JM, 2013. Survey of invasive plants occurring on National Park Service lands, 2000-2007. http://www.invasive.org/species/list.cfm?id=103
Timson J, 1996. Polygonum hydropiper L. Journal of Ecology, 54:815-821.
USDA-ARS, 2013. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx
USDA-NRCS, 2013. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/
Wagner WI; Herbst DR; Sohmer SH, 1999. Manual of the Flowering Plants of Hawaii, revised edition. Honolulu, Hawaii, USA: University of Hawaii Press.
Webb CJ; Sykes WR; Garnock-Jones PJ, 1988. Flora of New Zealand Volume IV. Naturalised Pteridophytes, Gymnosperms and Dicotyledons. Christchurch, New Zealand: DSIR Botany Division, 1365 pp. http://floraseries.landcareresearch.co.nz/pages/Book.aspx?fileName=Flora%204.xml
CABI, Undated. CABI Compendium: Status inferred from regional distribution. Wallingford, UK: CABI
Flora of North America, 2013. Flora of North America., FNA. http://www.efloras.org/flora_page.aspx?flora_id=1
Flora of Pakistan Editorial Committee, 2013. Flora of Pakistan. In: eFloras website, St. Louis, Missouri; Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria. http://www.efloras.org/flora_page.aspx?flora_id=5
GBIF, 2014. GBIF data portal., Copenhagen, Denmark: Global Biodiversity Information Facility (GBIF). http://data.gbif.org
PIER, 2013. Pacific Islands Ecosystems at Risk., Honolulu, Hawaii, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html
USDA-ARS, 2013. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysimple.aspx
USDA-NRCS, 2013. The PLANTS Database. Greensboro, North Carolina, USA: National Plant Data Team. https://plants.sc.egov.usda.gov
Webb CJ, Sykes WR, Garnock-Jones PJ, 1988. Flora of New Zealand. Naturalised Pteridophytes, Gymnosperms and Dicotyledons., IV Christchurch, New Zealand: DSIR Botany Division. 1365 pp. http://floraseries.landcareresearch.co.nz/pages/Book.aspx?fileName=Flora%204.xml
ContributorsTop of page
Original text by:
Ian Popay, consultant, New Zealand, with the support of Landcare Research.
Distribution MapsTop of page
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