Pacific Island Ecosystems at Risk (PIER)

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Equisetum arvense
L., Equisetaceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  High risk; score: 18 (Hawaii-Pacific Weed Risk Assessment for Equisetum arvense)

Other Latin names:  Equisetum boreale Bong.; Equisetum calderi B. Boivin; Equisetum saxicola Suksd.

Common name(s): [more details]

English: common horsetail, field horsetail, horsetail

Habit:  herb

Description:  "Horsetails are primitive plants without flowers or obvious leaves. Horsetails have two types of stem. The sterile stems are hollow and jointed, and some resemble giant sheoak shoots. The fertile stems produce spore-bearing cones at their tip." (Western Australian Government)

"A perennial plant, it [Equisetum arvense] grows to a height of 0.45 m with a spread of 0.5 m. ¶The rootstock is creeping, jointed and string-like; the stems are numerous and hollow--the fertile stems are flesh coloured and bear a terminal, cone-like spike, containing spores, and the sterile stems have whorls of small branchlets." (Encyclopaedia Botanica, p. 386)

"Aerial stems dimorphic; vegetative stems green, branched, 2-60(-100) cm; hollow center 1/3-2/3 stem diam. Sheaths squarish in face view, 2-5(-10) &mult; 2-5(-9) mm; teeth dark, 4-14, narrow, 1-3.5 mm, often cohering in pairs. Branches in regular whorls, ascending, solid; ridges 3-4; valleys channeled; 1st internode of each branch longer than subtending stem sheath; sheath teeth attenuate. Fertile stems brown, lacking stomates, unbranched, shorter than vegetative stems, with larger sheaths, fleshy, ephemeral. 2 n =ca. 216. . . . Cones maturing in early spring." (JSTOR Global Plants

Equisetum (genus): "Terrestrial, mostly in in wet places; rhiz subterranean, long-creeping; aerial stems erect, ribbed, jointed, internodes usu hollow. Lvs small, scalelike, whorled and fused to each other to form sheath at nodes. Cones (strobili) terminal on stem, composed of numerous peltate sporophylls; sporangia 5-10, on underside of sporophylls. Spores green, with 4 strap-shaped appendages." (a tropical garden flora, p. 38)

Habitat/ecology:  ". . .it [Equisetum arvense] prefers swampy, clayey soils, prefereably moist loams, in a protected position, and is frost resistant but drought tender." (Encyclopaedia Botanica, p. 386)

"The species grows in anthropogenic (man-made or disturbed habitats), fens (calcium-rich wetlands), forest edges, meadows and fields, shores of rivers or lakes, swamps and wetland margins (New England Wild Flower Society 2011-2015)" in both terrestrial and freshwater systems. (IUCN Red List)

Propagation:  "Propagation is by spore or by division." (Encyclopaedia Botanica, p. 386)

"Spreads primarily by rhizomes and root pieces, but also reproduces by spores." (Western Australian Government)

Native range:  "Indigenous to the temperate regions of the Northern Hemisphere. . . ." (Encyclopaedia Botanica, p. 386)

"The species is distributed throughout the temperate northern hemisphere, including nearly all of North America, Greenland, Eurasia, south to the Himalayas, central China, Korea and Japan (NatureServe 2014; Flora of North America Editorial Committee 1993+). . . . ¶Native: Åland Islands; Albania; Andorra; Austria; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; Canada (Alberta, British Columbia, Labrador, Manitoba, New Brunswick, Newfoundland I, Northwest Territories, Nova Scotia, Nunavut, Ontario, Prince Edward I., Québec, Saskatchewan, Yukon); China; Croatia; Czech Republic; Denmark; Estonia; Faroe Islands; Finland; France; Germany; Greece; Greenland; Guernsey; Hungary; Iceland; Ireland; Isle of Man; Italy; Japan; Jersey; Korea, Democratic People's Republic of; Latvia; Liechtenstein; Lithuania; Luxembourg; Macedonia, the former Yugoslav Republic of; Malta; Moldova; Monaco; Montenegro; Netherlands; Norway; Poland; Portugal (Azores - Introduced, Portugal (mainland)); Romania; Russian Federation; San Marino; Serbia; Slovakia; Slovenia; Spain (Baleares, Spain (mainland)); Svalbard and Jan Mayen; Sweden; Switzerland; Ukraine; United Kingdom; United States (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Georgia, Hawaiian Is. - Introduced, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington)" (IUCN Red List)

Impacts and invaded habitats:  In Australia: "Horsetails are highly invasive, difficult to control and toxic to livestock. They can be allelopathic." (Western Australian Government)

"Sometimes cultivated and extremely difficult to eradicate, especially in rocky soils. Grows mainly in damp places. Outbreaks have been controlled following spread from plantings in New South Wales, Victoria, Tasmania and Western Australia." (Western Australian Government)

If you know of other invaded habitats or impacts, please let us know.

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
State of Hawaii
Hawaiian Islands
O‘ahu Island   Consortium of Pacific Herbaria (2018)
Pacific Rim
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Asia
Asia
Himalayas   Maiz-Tome, L. (2016)
accessed 20180503
Asia
Asia
Iran   Randall, R. P. (2017) (p. 1393)
Asia
Asia
Mongolia   Randall, R. P. (2017) (p. 1393)
Asia
Asia
Nepal   Randall, R. P. (2017) (p. 1393)
Asia
Asia
Russia   Randall, R. P. (2017) (p. 1393)
Asia
Asia
Tajikstan   Randall, R. P. (2017) (p. 1393)
Asia
Asia
Ukraine native
Maiz-Tome, L. (2016)
accessed 20180503
Asia
Asia (Pacific rim)
Korea native
Maiz-Tome, L. (2016)
accessed 20180503
Australia
Australia
Western Australia (Australia) (state) introduced
invasive
cultivated
Western Australian Government (year unknown)
accessed 20190214
British Columbia (province of Canada)
Province of British Columbia
Canada (British Columbia) native
Maiz-Tome, L. (2016)
accessed 20180503
China
China
China (People's Republic of) native
Maiz-Tome, L. (2016)
accessed 20180503
Japan
Japan
Japan native
Maiz-Tome, L. (2016)
accessed 20180503
Japan
Japan
Shikoku (island)   Consortium of Pacific Herbaria (2018)
North Korea
North Korea
North Korea (Democratic People's Republic of)   Randall, R. P. (2017) (p. 1393)
New Zealand
New Zealand
South Island   Consortium of Pacific Herbaria (2018)
Russia
Russia
Russian Federation native
Maiz-Tome, L. (2016)
accessed 20180503
United States (west coast)
United States (west coast states)
USA (Oregon) introduced
Maiz-Tome, L. (2016)
accessed 20180503
United States (west coast)
United States (west coast states)
USA (California) native
Maiz-Tome, L. (2016)
accessed 20180503
United States (west coast)
United States (west coast states)
USA (Washington)   Consortium of Pacific Herbaria (2018)
Indian Ocean
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Mauritius
Mautitius Islands (Mauritius and Rodrigues)
Mauritius Island   Randall, R. P. (2017) (p. 1393)
Also reported from
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Africa
Africa
Azores   Randall, R. P. (2017) (p. 1393)
Africa
Africa
Madagascar   Randall, R. P. (2017) (p. 1393)
Canada
Canada
Canada native
Maiz-Tome, L. (2016)
accessed 20180503
Canada
Canada
Canada   Randall, R. P. (2017) (p. 1393)
Canada
Canada
Canada   Randall, R. P. (2017) (p. 1394)
Eurasia
Eurasia
Eurasia   Maiz-Tome, L. (2016)
accessed 20180503
Europe
Europe
Czechoslovakia   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Europe native
Maiz-Tome, L. (2016)
accessed 20180503
(see ref for details)
Europe
Europe
Europe (central)   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Europe (northern)   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Germany   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Kosovo   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Montenegro   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Netherlands   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Norway   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Poland   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Romania   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Slovakia   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Sweden   Randall, R. P. (2017) (p. 1393)
Europe
Europe
Yugoslavia   Randall, R. P. (2017) (p. 1393)
Iceland
Iceland
Iceland   Randall, R. P. (2017) (p. 1393)
North America
North America
Alaska (US) (state)   Randall, R. P. (2017) (p. 1393)
North America
North America
North America native
Maiz-Tome, L. (2016)
accessed 20180503
(see ref for details)
South America
South America
Argentina   Randall, R. P. (2017) (p. 1393)
United States (continental except west coast)
United States (other states)
United States (other states) native
Maiz-Tome, L. (2016)
accessed 20180503

Control:  "Invasive in wet places, species in this genus are extremely hard to control once they are established, being resistant to most herbicides." (NZ National Pest Plant Accord 2012, p. 58)

When using any agricultural chemicals please ensure that you always follow instructions on the label and any permit. Users of agricultural chemical products must always strictly comply with the directions on the label and the conditions of any permit. ... Chemical control options: Chemical control options can be found below. For other methods of control please refer to the aquatic weed control page, and the declared plant control handbook. Recommended herbicides: Dichlobenil. Herbicide: Casoron G (Group K). Active ingredient: 67.5g/kg dichlobenil. Rate of product: 370g/10m2. Time of application: Preferably when plants are dormant--usually in colder months. Wetting agent: N/A. Remarks: This a spot treatment only. ... Spread the granules evenly over the surface. A good method to aid the even distribution is to mix the granules in dry sand and then sprinkle over the area to be treated. Water treated area immediately application of the granules. Repeated applications will be necessary. Other control measures: Excavation and removal of soil and plant material, but this can be expensive and involves the risk of spreading the plant fragments. (Western Australian Government [text reformatted by PIER])


Need more info? Have questions? Comments? Information to contribute? Contact PIER! (pier@hear.org)

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This page was created on 12 SEP 2017 and was last updated on 15 FEB 2019.