The Rocky Mountain Floristic Region is a

floristic region A phytochorion, in phytogeography, is a geographic area with a relatively uniform composition of plant species. Adjacent phytochoria do not usually have a sharp boundary, but rather a soft one, a transitional area in which many species from both r ...

within the

Holarctic Kingdom The asterisk ( ), from Late Latin , from Ancient Greek , ''asteriskos'', "little star", is a typographical symbol. It is so called because it resembles a conventional image of a heraldic star. Computer scientists and mathematicians often voc ...

in western North America (

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

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 territori ...

) delineated by Armen Takhtajan and Robert F. Thorne. The region extends from

Kodiak Island Kodiak Island ( Alutiiq: ''Qikertaq''), is a large island on the south coast of the U.S. state of Alaska, separated from the Alaska mainland by the Shelikof Strait. The largest island in the Kodiak Archipelago, Kodiak Island is the second la ...

in Alaska to the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

and Sierra Nevada in

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. It consists of two provinces, the Vancouverian, which comprises the coastal part of the region for its entire length, including the Pacific Coast Ranges, and the Rocky Mountain, which includes the Rocky Mountains and associated ranges. There are no

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

plant families in the region but many endemic genera and species.

Geography

The region spans from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...

approximately to the

and Sierra Nevada of

, running between the shore of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...

on the west and the Great Plains on the east, along the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...

and

Pacific Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although the ...

. It is bordered by the Canadian Province of the

Circumboreal Region The Circumboreal Region in phytogeography is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan. It is the largest floristic region i ...

in the north, by the North American Prairies Province of the

North American Atlantic Region North American Atlantic Region is a floristic region within the Holarctic Kingdom identified by Armen Takhtajan and Robert F. Thorne, spanning from the Atlantic and Gulf coasts to the Great Plains and comprising a major part of the United States ...

in the east and by the Californian Province of the

Madrean Region The Madrean Region (named after the Sierra Madre Occidental) is a floristic region within the Holarctic Kingdom in North America, as delineated by Armen Takhtajan and Robert F. Thorne. It occupies arid or semiarid areas in the southwestern Unite ...

in the south. The borders with the Canadian and Californian Provinces are vague.

Flora

Although the Rocky Mountain Region has no

vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...

and only one endemic

Marchantiophyta The Marchantiophyta () are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of ...

family ( Gyrothyraceae), it has many endemic genera (such as ''

Sidalcea ''Sidalcea'' is a genus (approx. 25 species) of the botanical family Malvaceae. It contains several species of flowering plants known generally as checkerblooms or checkermallows, or prairie mallows in the United Kingdom. They can be annuals or ...

'', '' Luetkea'', '' Whipplea'', '' Vancouveria'', ''

Lithophragma ''Lithophragma'' is a genus of flowering plants in the saxifrage family containing about nine species native to western North America. These plants are known generally as woodland stars. The petals of the flowers are usually bright white with de ...

'', '' Tellima'', '' Tolmiea'', '' Luina'') and numerous endemic

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

. The genera ''

Arnica ''Arnica'' is a genus of perennial, herbaceous plants in the sunflower family (Asteraceae). The genus name ''Arnica'' may be derived from the Greek '' arni'', "lamb", in reference to the plants' soft, hairy leaves. ''Arnica'' is also known by th ...

'', ''

Castilleja ''Castilleja'', commonly known as paintbrush, Indian paintbrush, or prairie-fire, is a genus of about 200 species of annual and perennial herbaceous plants native to the west of the Americas from Alaska south to the Andes, northern Asia, and on ...

'', ''

Erigeron ''Erigeron'' () is a large genus of plants in the family Asteraceae. It is closely related to the genus '' Aster'' and the true daisies in the genus '' Bellis''. The genus has a cosmopolitan distribution in dry, mountainous areas and grassland, ...

'', and '' Lomatium'' have their major center of diversity here. The region possesses the greatest diversity of conifers in the

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...

. The remaining wildland of the province is covered mostly by

temperate coniferous forests Temperate coniferous forest is a terrestrial biome defined by the World Wide Fund for Nature. Temperate coniferous forests are found predominantly in areas with warm summers and cool winters, and vary in their kinds of plant life. In some, needl ...

(such as

Northern California coastal forests The Northern California coastal forests are a temperate coniferous forests ecoregion of coastal Northern California and southwestern Oregon. Setting The ecoregion covers , extending from just north of the California-Oregon border south, to south ...

Maritime Coast Range Ponderosa Pine forests The maritime coast range ponderosa pine forests are rare temperate forest assemblages associated with a limited range portion of the Santa Cruz Mountains of northern California. There are only three known small forests of this type, all situated in ...

Klamath-Siskiyou forests The Klamath Mountains ecoregion of Oregon and California lies inland and north of the Coast Range ecoregion, extending from the Umpqua River in the north to the Sacramento Valley in the south. It encompasses the highly dissected ridges, foothi ...

, British Columbia mainland coastal forests, Fraser Plateau and Basin complex,

Northern Pacific coastal forests The Northern Pacific coastal forests are temperate coniferous forest ecoregion of the Pacific coast of North America. It occupies a narrow coastal zone of Alaska, between the Pacific Ocean and the northernmost Pacific Coast Ranges, covering an ...

) dominated by '' Pinus ponderosa'', ''

Pinus contorta ''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpine ...

'' and ''

Pseudotsuga menziesii The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...

'', as well as the alpine tundra above timberline. The region is subdivided further into the Vancouverian Province and Rocky Mountain Province. The Vancouverian Province comprises the coastal part of the region for its entire length, including the

. Such plant species and genera as ''

Sequoia sempervirens ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995:606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal ...

'', ''

Sequoiadendron giganteum ''Sequoiadendron giganteum'' (giant sequoia; also known as giant redwood, Sierra redwood, Sierran redwood, California big tree, Wellingtonia or simply big treea nickname also used by John Muir) is the sole living species in the genus '' Sequoiad ...

'', '' Darlingtonia californica'', '' Vancouveria'' and '' Whipplea'' are endemic to it. The boundary with the Californian Province is not well-defined. The Rocky Mountain Province includes the Rocky Mountains and associated ranges. Due to more heavy

glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...

during the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

, its flora, especially in the north, has a far lower degree of endemism than that of the Vancouverian Province. Much of it is shared with the Canadian Province and the Circumboreal Region in general.Thorne, Robert F
Phytogeography of North America North of Mexico
. '' Flora of North America'', Vol. 1, Ch. 6.

References

{{Reflist Floristic regions * * Plant communities of the Western United States * * * * * * Rocky Mountain Floristic Region * * Plant communities of the West Coast of the United States Plant communities of California F