Sweet coltsfoot (Petasites sagittatus)

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Sweet coltsfoot flowers

Top facts

  • The genus name of the sweet coltsfoot, Petasites, comes from the Greek word for a wide-brimmed hat, and refers to this plant’s large leaves.
  • The arrowhead-shaped leaves of the sweet coltsfoot give it its species name, sagittatus, which means ‘formed like arrows’.
  • The sweet coltsfoot has long been used in herbal medicine to treat coughs and colds.
  • The seeds of the sweet coltsfoot have a tuft of hairs at one end to help in wind dispersal.
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Sweet coltsfoot fact file

Sweet coltsfoot description

KingdomPlantae
PhylumTracheophyta
ClassMagnoliopsida
OrderAsterales
FamilyAsteraceae
GenusPetasites (1)

The sweet coltsfoot is a perennial herb (2) (3) with an accurately descriptive scientific name. The genus name Petasites is derived from the Greek word for a wide-brimmed hat, ‘petasos’, and refers to this species’ large leaves, which grow on stalks from the base of the flowering stem (4) (5).

The leaves of the sweet coltsfoot are arrowhead-shaped (2) (5) (6) (7) with toothed edges (3) (7) (8), and are located on the ends of long, hairy stalks (4) (6). The upper sides of the leaves are greyish-green (7) (9), while the undersides have a dense white, woolly texture (2) (4) (6) (9). The leaves grow to lengths of between 10 and 30 centimetres and widths of 10 to 20 centimetres (7) (9).

The sweet coltsfoot has a single erect, hollow, round stem, which is slightly ridged and hairy (2) and grows from cordlike, creeping rhizomes (3) (6) (7). Instead of leaves, the stem has overlapping, sheathing bracts (4) (5) (6). Growing to a height of between 20 and 70 centimetres (2), the stem ends in a tight cluster of white flower heads (3) (4) (6) (7), which are reported to be quite fragrant and are covered in copious silky white hairs (6).

The brown, one-seeded fruit of the sweet coltsfoot, known as an achene (2) (5) (6) (9), has a tuft of long, white, bristle-like hairs at one end, which aids with wind dispersal (5) (6).

Size
Height: 20 - 70 cm (2)
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Sweet coltsfoot biology

A perennial plant (5) (6) (7), the sweet coltsfoot flowers in early spring (6) (7), before the leaves develop (6) (9). The exact time at which the flowers bloom depends on the location, with some populations flowering between April and July (2), and others only in May and June (10).

The sweet coltsfoot has separate male and female flowers, which are usually found on different plants (2) (9). Colonies of the sweet coltsfoot may be composed of just a few genetically distinct individuals, as the species can reproduce vegetatively, producing clones by means of the rhizomes (6).

The sweet coltsfoot is in fruit from late spring to early summer, and its wind-borne seeds are released in early summer (6).

The sweet coltsfoot has long been used in herbal medicine (4), with a syrup made of the leaves, water and honey being used to treat coughs and colds (9). The leaves of Petasites species have also been used in poultices for wounds and inflammations (4).

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Sweet coltsfoot range

The sweet coltsfoot ranges across the North American Arctic, from Alaska to Quebec, and southwards through Idaho, Wisconsin, Minnesota, Wyoming and South Dakota, with its southern limit in Colorado (6) (7). This species is considered to be rare in Wisconsin, Idaho, Wyoming and South Dakota (6).

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Sweet coltsfoot habitat

The sweet coltsfoot is found from low to subalpine elevations (4), and occurs in a variety of wetland habitats including wet meadows, slough margins, ditches, swamps, fens and bogs (2) (7) (9). It has also been reported in wet forests and thickets (2) (10), and occasionally in standing water (4).

In the Prairie Provinces of Canada, the sweet coltsfoot is particularly abundant in wet grassland areas, parkland, the Rocky Mountain foothills, and boreal forest (7).

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Sweet coltsfoot status

The sweet coltsfoot has yet to be assessed by the IUCN Red List.

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Sweet coltsfoot threats

There are currently no known major threats to the sweet coltsfoot, although human activities have been reported to impact upon the species, with the largest colony in Michigan sustaining severe damage in the early 1980s due to the construction of a logging road (6).

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Sweet coltsfoot conservation

The sweet coltsfoot is classified as ‘Threatened’ in Wisconsin (10) (11), as well as in Michigan (6) (11), where the majority of the populations of this species are found on state or national forest lands (6).

In Menominee County, Michigan, attempts are being made to mitigate the negative effects of road reconstruction on the local populations of the sweet coltsfoot. Other activities such as timber removal are also thought to cause disturbance to the natural water systems of the area, and so studies to determine the water requirements of this species are important. Further research into the genetics and breeding biology of the sweet coltsfoot would also be of use to its conservation (6).

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Find out more

Learn more about plant conservation in the United States:

Find out more about the sweet coltsfoot:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Achene
A simple single-seeded fruit that falls from the plant in one piece. Achenes usually in occur in clusters.
Boreal forest
The sub-Arctic forest of the high northern latitudes that surrounds the North Pole and is mainly composed of coniferous trees.
Bract
Modified leaf at the base of a flower.
Genus
A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
Herb
A small, non-woody, seed bearing plant in which all the aerial parts die back at the end of each growing season.
Perennial
A plant that normally lives for more than two years. After an initial period, the plant usually produces flowers once a year.
Rhizome
An underground, horizontal plant stem that produces roots and shoots.
Vegetative reproduction
Type of asexual reproduction (reproduction that does not involve the formation of sex cells) in which a new plant grows from part of another plant, rather than from seeds or spores. The resulting individual is genetically identical to the original plant.
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References

  1. Species 2000 and ITIS Catalogue of Life (August, 2012)
    http://www.catalogueoflife.org/
  2. Reaume, T. (2009) 620 Wild Plants of North America. CPRC Press, Saskatchewan.
  3. Cody, W.J. (2000) Flora of the Yukon Territory. NRC Research Press, Ontario.
  4. Jennings, N.L. (2008) Central Beauty: Wildflowers and Flowering Shrubs of the Southern Interior of British Columbia. Rocky Mountain Books Ltd., British Columbia.
  5. Hallworth, B. and Chinnappa, C.C. (1993) Plants of Kananaskis Country in the Rocky Mountains of Alberta. University of Calgary Press, Alberta.
  6. Penskar, M.R., Crispin, S.R. and Higman, P.J. (1997) Special Plant Abstract for Petasites sagittatus (Arrow-leaved Sweet-coltsfoot). Michigan Natural Features Inventory, Lansing, Michigan. Available at:
    http://mnfi.anr.msu.edu/abstracts/botany/Petasites_sagittatus.pdf
  7. Lahring, H. (2003) Water and Wetland Plants of the Prairie Provinces. CPRC Press, Canadian Plains Research Center, University of Regina, Canada.
  8. Rabeler, R.K. (2007) Gleason's Plants of Michigan: A Field Guide. University of Michigan Press, Michigan.
  9. Royer, F. and Dickinson, R. (1996) Wild Flowers of Edmonton and Central Alberta. University of Alberta Press, Alberta.
  10. Black, M.R. and Judziewicz, E.J. (2009) Wildflowers of Wisconsin and the Great Lakes Region: A Comprehensive Field Guide. University of Wisconsin Press, Wisconsin.
  11. USDA Natural Resources Conservation Service - Arrowleaf sweet coltsfoot (August, 2012)
    http://plants.usda.gov/java/profile?symbol=pefrs5
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Image credit

Sweet coltsfoot flowers  
Sweet coltsfoot flowers

© Blake Maybank

Blake Maybank
bmaybank@gmail.com
http://tinyurl.com/canbird

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