Flora of the United States

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The native flora of the United States includes about 17,000 species of vascular plants, plus tens of thousands of additional species of other plants and plant-like organisms such as algae, lichens and other fungi, and mosses. About 3,800 additional non-native species of vascular plants are recorded as established outside of cultivation in the U.S., as well as a much smaller number of non-native non-vascular plants and plant relatives. The United States possesses one of the most diverse temperate floras in the world, comparable only to that of China. [1]

Contents

Several biogeographic factors contribute to the richness and diversity of the U.S. flora. While most of the United States has a temperate climate, Alaska has vast arctic areas, the southern part of Florida is tropical, as well as Hawaii (including high mountains), and the U.S. territories in the Caribbean and the Pacific, and alpine summits are present on many western mountains, as well as a few in the Northeast. The U.S. coastline borders three oceans: The Atlantic (and Gulf of Mexico), the Arctic, and the Pacific. Finally, the U.S. shares long borders with Canada and Mexico, and is relatively close to the Bahamas, Cuba and other Caribbean islands, and easternmost Asia. There are also rainforests as well as some of the driest deserts in the world.

The native flora of the United States has provided the world with a large number of horticultural and agricultural plants, mostly ornamentals, such as flowering dogwood, redbud, mountain laurel, bald cypress, southern magnolia, and black locust, all now cultivated in temperate regions worldwide, but also various food plants such as blueberries, black raspberries, cranberries, maple syrup and sugar, and pecans, and Monterey pine and other timber trees.

Some of the native U.S. plants, such as Franklinia alatamaha, have demonstrably become extinct or extinct in the wild; others, such as Micranthemum micranthemoides , have not been seen in decades, but may still be extant. Thousands of other native U.S. vascular plants are considered rare, threatened, or endangered, either globally (rangewide) or within particular states.

Divisions

According to Armen Takhtajan, Robert F. Thorne, and other geobotanists, the territory of the United States (including Hawaii and Alaska) is divided between three floristic kingdoms, six floristic regions and twelve floristic provinces, characterized by a certain degree of endemism:

Holarctic Kingdom
Circumboreal crack ]
Arctic Province
Canadian Province
North American Atlantic Region
Appalachian Province
Atlantic and Gulf Coastal Plain Province
North American Prairies Province
Rocky Mountain Region
Vancouverian Province
Rocky Mountain Province
Madrean Region
Great Basin Province
Californian Province
Sonoran Province
Neotropical Kingdom
Caribbean Region
West Indian Province
Paleotropic Kingdom
Hawaiian Region
Hawaiian Province

Some prominent botanists who have studied and published on U.S. flora

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The term "United States," when used in the geographical sense, refers to the contiguous United States, Alaska, Hawaii, the five insular territories of Puerto Rico, Northern Mariana Islands, U.S. Virgin Islands, Guam, American Samoa, and minor outlying possessions. The United States shares land borders with Canada and Mexico and maritime borders with Russia, Cuba, The Bahamas, and many other countries, mainly in the Caribbeanin addition to Canada and Mexico. The northern border of the United States with Canada is the world's longest bi-national land border.

<span class="mw-page-title-main">Nearctic realm</span> Biogeographic realm encompassing temperate North America

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<span class="mw-page-title-main">Antarctic flora</span> Distinct community of plants which evolved on the supercontinent of Gondwana

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<span class="mw-page-title-main">Boreal Kingdom</span> Floristic kingdom in northern Eurasia and the Americas

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<span class="mw-page-title-main">California Floristic Province</span> Region of uniform plant variety in the western United States and Mexico

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<span class="mw-page-title-main">Cape Floristic Region</span> Smallest of the six recognised floral kingdoms of the world

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<span class="mw-page-title-main">North American Atlantic Region</span> Floristic region in the Holarctic kingdom

The 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 and southeastern portions of Canada. It is bordered by the Circumboreal floristic region in the north, by the Rocky Mountain and Madrean floristic regions in the west and by the Caribbean floristic region of the Neotropical Kingdom in the south of Florida. The flora of the region comprises two endemic monotypic families, Hydrastidaceae and Leitneriaceae, and is characterized by about a hundred of endemic genera. The degree of species endemism is very high, many species are Tertiary relicts, which survived the Wisconsin glaciation and are now concentrated in the Appalachians and the Ozarks. A number of genera are shared only with the Canadian floristic province of the Circumboreal region. Moreover, as has long been noted, a large number of relict genera are shared with the relatively distant Eastern Asiatic Region and sometimes Southeast Asia. R. F. Thorne counted at least 74 genera restricted to eastern North America and Asia. The fossil record indicates that during the Tertiary period a warm temperate zone extended across much of the Northern Hemisphere, linking America to Asia.

<span class="mw-page-title-main">Antarctic Floristic Kingdom</span> Geographic area with a relatively uniform composition of plant species in the Antarctic

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<span class="mw-page-title-main">Rocky Mountain Floristic Region</span>

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<span class="mw-page-title-main">Madrean Region</span> Floristic region in the Holarctic Kingdom

The Madrean Region 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 United States and northwestern Mexico and is bordered by the Rocky Mountain Floristic Region and North American Atlantic Region of the Holarctic Kingdom in the north and in the east, Caribbean Region of the Neotropical Kingdom in the south.

<span class="mw-page-title-main">Circumboreal Region</span> Floristic region in Eurasia and North America

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.

<span class="mw-page-title-main">Paleotropical Kingdom</span> One of the Earths six floristic kingdoms

The Paleotropical Kingdom (Paleotropis) is a floristic kingdom composed of the tropical areas of Africa, Asia and Oceania, as proposed by Ronald Good and Armen Takhtajan. Part of its flora is inherited from the ancient supercontinent of Gondwana or exchanged later. These Gondwanan lineages are related to those in the Neotropical Kingdom, composed of the tropical areas of Central and South America. Flora from the Paleotropical Kingdom influenced the tropical flora of the Australian Kingdom. The kingdom is subdivided into five floristic subkingdoms according to Takhtajan and about 13 floristic regions. In this article the floristic subkingdoms and regions are given as delineated by Takhtajan.

Allium dictuon is a species of wild onion known by the common name Blue Mountain onion. It is native to a small section of the Blue Mountains straddling the border between southeastern Washington and northeastern Oregon in the United States. It grows in Columbia, Garfield and Walla Walla Counties in Washington, plus Umatilla and Wallowa Counties in Oregon.

References

  1. Encyclopedia of Biology. p. 338.

Further reading