| Hill's thistle | |
|---|---|
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Cirsium |
| Species: | |
| Variety: | C. p. var. hillii |
| Trinomial name | |
| Cirsium pumilum var. hillii (Canby) B. Boivin | |
| Synonyms [1] | |
| |
Cirsium pumilum var. hillii is a type of thistle endemic to North America. The common name for this plant is Hill's thistle. [1]
Hill's thistle is a low-growing thistle usually reaching 25 to 60 cm (10 to 23.5 in) in height, with a taproot system that runs deep into the ground. [2] It is a perennial plant usually living for three years, and flowers in July and August. [2] The plant's leaves are an elliptic-oblong shape with serrated edges, have tiny prickles, and have one central vein with smaller veins branching from it. [3]
The top of the stem holds a composite flower head, each consisting of many individual disc florets but no ray florets. [3] The flowers of this plant are usually purple though sometimes pink or white. [2] Hill's thistle tends to looks very similar to Cirsium vulgare during its seedling and rosette stages; one can easily be mistaken for the other. [3] [4]
Hill's thistle thrives in areas that are open, sandy, and dry. It also grows well in areas that are susceptible to fire and areas lacking tall vegetation. [2] Its preferred habitats include sand prairies, sand dunes, open wooded areas, and limestone plains with thin soil and little vegetation. [2] Natural fires are important for Hill's thistle because they burn large trees and debris, which reduces competition and allows it to grow. [2]
Hill's thistle is an endemic species to North America, found only in Canada and the United States. [2] It is found around the Great Lakes, in the southern part of Ontario, as well as Michigan, Wisconsin, Minnesota, Iowa, Illinois and Indiana. [2] [5]
Hill's thistle is not used for medicine, food, or fibres. [2] This lack of utility may be beneficial to its persistence in the wild, as it has been suggested that samples only be collected for scientific reasons. [3] It does, however, play an important role in its ecosystem because it is consumed by whitetail deer. [2] Multiple plants grow near Hill's thistle, such as big and little bluestem, blazing star, rough fescue, pale agoseris, juniper, hair grass, western sunflower, and field chickenweed. [6] Because Hill's thistle is one of the first plants to colonize its habitat, perhaps it plays a role in stabilizing the soil and benefits these other plants.
The Committee of the Status of Endangered Wildlife in Canada last examined Hill's thistle in 2004 and named it as "threatened" due to its "rarity, restricted range, and human factors, which make it susceptible to extinction,". [2] The plant's main threats include aggregate demand, shoreline development, and invasive species. [2] Human recreation and development encroachment may also negatively impact Hill's thistle. [2]
Hill's thistle generally only lives to be 2 or 3 years old, typically flowering at 3 years. [2] This could pose a problem in terms of conservation because, if fewer plants survive to the flowering stage at the end of their life, there will be less production of offspring.
Lack of disturbance by natural fires is another reason why Hill's thistle is threatened. [2] This plant needs an open, dry, grassy environment in order to thrive. [2] Areas where it previously succeeded are now managed to prevent fires, allowing the invasion of shrubs and trees, which outcompete the open-habitat species. [7]
Hill's thistle is a rare species found in relatively few places around the globe and thus ongoing conservation efforts are essential for its survival. [7] Suggestions for the conservation of this species include reducing shoreline development and aggregate demand in its habitat. [2] Conservation efforts should also focus determining how management of fires affects seedling establishment and what can be done in regards to fire reduction. [6]
Cirsium is a genus of perennial and biennial flowering plants in the Asteraceae, one of several genera known commonly as thistles. They are more precisely known as plume thistles. These differ from other thistle genera in having feathered hairs to their achenes. The other genera have a pappus of simple unbranched hairs.
Cirsium vulgare, the spear thistle, bull thistle, or common thistle, is a species of the Asteraceae genus Cirsium, native throughout most of Europe, Western Asia, and northwestern Africa. It is also naturalised in North America, Africa, and Australia and is an invasive weed in some areas. It is the national flower of Scotland.
Cirsium arvense is a perennial species of flowering plant in the family Asteraceae, native throughout Europe and western Asia, northern Africa and widely introduced elsewhere. The standard English name in its native area is creeping thistle. It is also commonly known as Canada thistle and field thistle.
Cirsium edule, the edible thistle or Indian thistle, is a species of thistle in the genus Cirsium, native to western North America from southeastern Alaska south through British Columbia to Washington and Oregon, and locally inland to Idaho. It is a larval host to the mylitta crescent and the painted lady.
A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or livestock. Most noxious weeds have been introduced into an ecosystem by ignorance, mismanagement, or accident. Some noxious weeds are native. Typically they are plants that grow aggressively, multiply quickly without natural controls, and display adverse effects through contact or ingestion. Noxious weeds are a large problem in many parts of the world, greatly affecting areas of agriculture, forest management, nature reserves, parks and other open space.
Cirsium pitcheri, sometimes called Pitcher's thistle or dune thistle, is a species of thistle native to sand dune shorelines along the upper Great Lakes. It is native to Indiana, Illinois, Michigan, Wisconsin, and Ontario. It is listed by the U.S. Fish and Wildlife Service as a threatened species.
Cirsium eriophorum, the woolly thistle, is a herbaceous biennial species of the genus Cirsium. It is widespread across much of Europe. It is a large, biennial herb with sharp spines on the tips of the leaves, and long, woolly hairs on much of the herbage. Flower heads are large and nearly spherical, with spines on the outside and many purple disc florets but no ray florets.
Cirsium discolor, the field thistle, is a North American species of plants in the thistle tribe, within the sunflower family. It is native to thirty-three states in the United States as well four Canadian provinces. It occurs across much of eastern and central Canada as well as eastern and central United States. It has been found from New Brunswick west to Saskatchewan and south as far as Texas and Georgia.
Cirsium scariosum is a species of thistle known by the common names meadow thistle, elk thistle and dwarf thistle. It is native to much of western North America from Alberta and British Columbia south to Baja California. There are also isolated populations on the Canadian Atlantic Coast, on the Mingan Archipelago in Québec.
Tetraneuris herbacea is a rare species of flowering plant in the aster family known by the common names eastern fournerved daisy, lakeside daisy, fournerved starflower, and Manitoulin gold. It is native to and endemic to the Great Lakes region in North America, where it is present in Ontario, Ohio, Michigan, and Illinois. It is threatened by habitat destruction and degradation by several forces, including limestone quarrying, recreational activity, fire suppression, and construction. It is a federally listed threatened species of the United States and of Canada.
Spiranthes diluvialis is a rare species of orchid known as Ute lady's tresses. The species name diluvialis means "of the flood". It is native to the western United States, where there are scattered, mostly small occurrences in the states of Colorado, Idaho, Montana, Nebraska, Nevada, Utah, Washington, and Wyoming. An occurrence was recently discovered in southern British Columbia. The plant faces a number of threats to its existence. It is a federally listed threatened species of the United States.
Cirsium muticum, also known as swamp thistle, marsh thistle, dunce-nettle, or horsetops, is a North American species of plants in the sunflower family, native to central and eastern Canada and the central and eastern United States.
Erigeron kachinensis is a species of flowering plant in the aster family known by the common names Kachina fleabane and Kachina daisy. It is native to Utah and Colorado in the United States. It is an endemic of the Colorado Plateau.
Cirsium perplexans is a species of flowering plant in the aster family known by the common names Rocky Mountain thistle and Adobe Hills thistle. It is endemic to Colorado in the United States, where it occurs in the Colorado and Gunnison River Valleys in the Rocky Mountains.
Carex lacustris, known as lake sedge, is a tufted grass-like perennial of the sedge family (Cyperaceae), native to southern Canada and the northern United States. C. lacustris us an herbaceous surface-piercing plant that grows in water up to 50 cm (1.6 ft) deep, and grows 50–150 cm (1.6–4.9 ft) tall. It grows well in marshes and swampy woods of the boreal forest, along river and lake shores, in ditches, marshes, swamps, and other wetland habitat. It grows on muck, sedge peat, wet sand or silt, in filtered or full sunlight.
Cirsium carolinianum is a North American species of plants in the thistle tribe within the sunflower family. Common name is Carolina thistle or purple thistle or soft thistle or smallhead thistle. The species is native to the central and southern United States, from eastern Texas east to Virginia and the Carolinas, north to the Ohio Valley.
Cirsium clavatum, the Fish Lake thistle or fringed thistle, is a North American species of plants in the thistle tribe within the sunflower family. The species is native to the western United States, the States of Wyoming, Colorado, Utah, Arizona, and New Mexico.
Cirsium helenioides, called melancholy thistle, is an Asian and Arctic species of plants in the thistle tribe within the sunflower family. The species is native to Greenland, Iceland, Norway, Sweden, Finland, Russia, Xinjiang, Kazakhstan.
Cirsium pumilum, the pasture thistle, is a North American species of plants in the thistle tribe within the sunflower family. The species is native to the northeastern and north-central United States as well as to the Canadian Province of Ontario.
Cirsium repandum is a North American species of plants in the thistle tribe within the sunflower family. Common names include sand-hill thistle and coastal-plain thistle. The species is native to the southeastern United States, the coastal plain in Virginia, Georgia, and the Carolinas.
