''Cirsium muticum'', also known as swamp thistle, marsh thistle, dunce-nettle, or horsetops, is a

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

n species of plants in the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

, native to central and eastern

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

and the central and eastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

Description

''Cirsium muticum'' is a

biennial plant A biennial plant is a flowering plant that, generally in a temperate climate, takes two years to complete its biological life cycle. Life cycle In its first year, the biennal plant undergoes primary growth, during which its vegetative structures ...

that reaches a height of . Its taproot is fleshy and its stem is ridged with hairs toward the base. The leaves are

alternate Alternative or alternate may refer to: Arts, entertainment and media * Alternative (''Kamen Rider''), a character in the Japanese TV series ''Kamen Rider Ryuki'' * ''The Alternative'' (film), a 1978 Australian television film * ''The Alternative ...

in position,

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

ly lobed, and ovate in shape. The leaf lobes are often asymmetrical and forked irregularly with the angles containing fine

trichome Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a pla ...

s (multicellular hairs). The leaves become progressively smaller towards the

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

; there are often a few trichomes on the underside. The peduncles are , each with an

made up of many tiny

floret This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

s; the involucre has cobwebby white hairs, and it is often slightly sticky. The purple

s can be up to long.

Taxonomy and naming

''Cirsium muticum'' was described by the French naturalist André Michaux in 1803. It is one of many species in the thistle genus '' Cirsium''. The epithet muticum, meaning blunt, refers to its phyllaries.

Distribution and habitat

''Cirsium muticum'' has been found across every province of

from

Labrador , nickname = "The Big Land" , etymology = , subdivision_type = Country , subdivision_name = Canada , subdivision_type1 = Province , subdivision_name1 ...

and

Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...

Saskatchewan Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...

. In the

, it grows primarily in the

Northeast The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each se ...

, the Great Lakes region, and the Appalachians, with isolated populations scattered across the

South South is one of the cardinal directions or Points of the compass, compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Pro ...

from

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

to the

Carolinas The Carolinas are the U.S. states of North Carolina and South Carolina, considered collectively. They are bordered by Virginia to the north, Tennessee to the west, and Georgia to the southwest. The Atlantic Ocean is to the east. Combining Nort ...

. ''Cirsium muticum'' is found mostly in alkaline swamps,

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

es and low

forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

s but some races have been known to grow in wet

alpine climate Alpine climate is the typical weather (climate) for elevations above the tree line, where trees fail to grow due to cold. This climate is also referred to as a mountain climate or highland climate. Definition There are multiple definitions of ...

Ecology

''Cirsium muticum'' is as host for some species of butterflies and moths, including the swamp metalmark butterfly ('' Calephelis muticum''), a species that is currently undergoing risk assessment in the United States. The butterfly lays its eggs on the swamp thistle, and when the eggs hatch, the flowers are the only food source for the caterpillars. It is also a larval host to the painted lady butterfly, and songbirds eat its seeds.The Xerces Society (2016), ''Gardening for Butterflies: How You Can Attract and Protect Beautiful, Beneficial Insects'', Timber Press. Species that grow with it include ''

Aster umbellatus ''Doellingeria umbellata'', known by the common names tall flat-topped white aster, parasol whitetop, or tall white-aster, is a North American plant species in the family Asteraceae. It is native to Canada (from Alberta to Newfoundland), St. Pier ...

'' (flat-topped white aster), ''

Solidago patula ''Solidago patula'', the roundleaf goldenrod or rough-leaved goldenrod, is a species of Solidago, goldenrod found in wetlands, especially swamps, fens, and sedge meadows. It is native to most of the eastern United States, as far west as Wisconsin ...

'' (rough-leaved goldenrod), ''

Lysimachia quadrifolia ''Lysimachia quadrifolia'', the whorled loosestrife, whorled yellow loosestrife, or crosswort, is a species of herbaceous plant in the family Primulaceae The Primulaceae , commonly known as the primrose family (but not related to the evening ...

'' (prairie loosestrife), and '' Gentiana procera'' (smaller fringed gentian).

Human importance

Swamp thistles can be used to make decorative arrangements. They are often planted in gardens because they are seen as more manageable than other thistles, while still potentially having some anti-herbivory properties.

Conservation

The plant is not endangered in Canada or the U.S. but it is threatened in the state of

Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the Osage ...

, and vulnerable in the province of Saskatchewan. ''Cirsium muticum'' is at risk primarily because it is a wetland plant, and North American wetlands have been much reduced in extent over the last two centuries.

References

External sources

* {{Taxonbar, from=Q5122064 muticum Flora of Canada Flora of the Eastern United States Flora of the United States Plants described in 1803 Taxa named by André Michaux