The native

flora Flora (: floras or florae) is all the plant life present in a particular region or time, generally the naturally occurring (indigenous (ecology), indigenous) native plant, native plants. The corresponding term for animals is ''fauna'', and for f ...

of the United States includes about 17,000

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

of vascular plants, plus tens of thousands of additional species of other

plant Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...

s and plant-like

organisms In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and f ...

such as algae, lichens and other

fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...

, 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. Several biogeographic factors contribute to the richness and diversity of the U.S. flora. While most of the United States has a

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologica ...

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 ...

has vast

arctic The Arctic ( or ) is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada ( Yukon, Northwest Territories, Nunavut), Danish Realm ( Greenland), Finland, Iceland ...

areas, the southern part of

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, a ...

is tropical, as well as

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only ...

(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 The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe an ...

(and

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United S ...

), the

Arctic The Arctic ( or ) is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada ( Yukon, Northwest Territories, Nunavut), Danish Realm ( Greenland), Finland, Iceland ...

, and the Pacific. Finally, the U.S. shares long borders with Canada and Mexico, and is relatively close to the

Bahamas The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to 88% of the archi ...

Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...

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 Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...

and

agricultural Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peopl ...

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

pecan The pecan (''Carya illinoinensis'') is a species of hickory native to the southern United States and northern Mexico in the region of the Mississippi River. The tree is cultivated for its seed in the southern United States, primarily in Georgia, ...

s, and Monterey pine and other timber trees. Some of the native U.S. plants, such as ''

Franklinia alatamaha ''Franklinia'' is a Monotypic taxon, monotypic genus in the Camellia sinensis, tea family, Theaceae. The sole species in this genus is a flowering tree, ''Franklinia alatamaha'', commonly called the Franklin tree, and native to the Altamaha Rive ...

,'' 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

and

) is divided between three floristic kingdoms, six floristic regions and twelve floristic provinces, characterized by a certain degree of

endemism 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 els ...

: : Holarctic Kingdom ::

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 ...

::: Arctic Province ::: Canadian Province :: North American Atlantic Region :::

Appalachian Province The Appalachian Province is a floristic province within the North American Atlantic Region, a floristic region within the Holarctic Kingdom. It was historically covered by deciduous forest. The province includes southern Ontario and Quebec, down t ...

:::

Atlantic and Gulf Coastal Plain Province The Atlantic and Gulf Coastal Plain Province is a coastal plain floristic province within the North American Atlantic Region, a floristic region within the Holarctic Kingdom. It lies to the east and south of the Appalachian Province. It encompasses ...

::: 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 The Paleotropical Kingdom (Paleotropis) is a floristic kingdom comprising tropical areas of Africa, Asia and Oceania (excluding Australia and New Zealand), as proposed by Ronald Good and Armen Takhtajan. Part of its flora, inherited from the ancient ...

Hawaiian Region Hawaiian may refer to: * Native Hawaiians, the current term for the indigenous people of the Hawaiian Islands or their descendants * Hawaii state residents, regardless of ancestry (only used outside of Hawaii) * Hawaiian language Historic uses * ...

::: Hawaiian Province

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

John Clayton John Clayton may refer to: Arts and entertainment Writing * John Clayton (architect) (died 1861), English architect and writer * John Bell Clayton (c. 1907–1955), American writer * John Clayton (sportswriter) (1954–2022), American sportswriter ...

(1694–1773) * John Bartram (1699–1777) *

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...

(1707–1778) * Peter Kalm (1716–1779) * William Bartram (1739–1823) *

André Michaux André Michaux, also styled Andrew Michaud, (8 March 174611 October 1802) was a French botanist and explorer. He is most noted for his study of North American flora. In addition Michaux collected specimens in England, Spain, France, and even Pe ...

(1746–1802) * William Clark (1770–1838) * Meriwether Lewis (1774–1809) *

Frederick Traugott Pursh Frederick Traugott Pursh (or Friedrich Traugott Pursch) (February 4, 1774 – July 11, 1820) was a German– American botanist. Born in Großenhain, Saxony, under the name Friedrich Traugott Pursh, he was educated at Dresden Botanical Gardens, ...

(1774–1820) *

Alphonse Louis Pierre Pyramus de Candolle Alphonse may refer to: * Alphonse (given name) * Alphonse (surname) * Alphonse Atoll Alphonse Atoll is one of two atolls of the Alphonse Group, the other being St. François Atoll — both in the Outer Islands (Coralline Seychelles) coral arch ...

(1778–1841) *

Constantine Samuel Rafinesque Constantine Samuel Rafinesque-Schmaltz (; October 22, 1783September 18, 1840) was a French 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ultima ...

(1783–1840) * Thomas Nuttall (1786–1859) * John Torrey (1796–1873) * George Engelmann (1809–1884) *

Asa Gray Asa Gray (November 18, 1810 – January 30, 1888) is considered the most important American botanist of the 19th century. His '' Darwiniana'' was considered an important explanation of how religion and science were not necessarily mutually ex ...

(1810–1888) * George Vasey (1822–1893) * Sereno Watson (1826–1892) *

Charles Sprague Sargent Charles Sprague Sargent (April 24, 1841 – March 22, 1927) was an American botanist. He was appointed in 1872 as the first director of Harvard University's Arnold Arboretum in Boston, Massachusetts, and held the post until his death. He p ...

(1841–1927) * Edward Lee Greene (1843–1915) * John Merle Coulter (1851–1928) * Marcus Eugene Jones (1852–1934) * Liberty Hyde Bailey (1858–1954) * Nathaniel Lord Britton (1859–1934) *

Aven Nelson Aven Nelson (March 24, 1859 – March 31, 1952) was an American botanist who specialized in plants of the Rocky Mountains. He was one of the founding professors of the University of Wyoming, where he taught for 55 years as professor and served as ...

(1859–1952) * Per Axel Rydberg (1860–1931) *

Alfred Rehder Alfred Rehder (4 September 1863 in Waldenburg, Saxony – 25 July 1949 in Jamaica Plain, Massachusetts) was a German-American botanical taxonomist and dendrologist who worked at the Arnold Arboretum of Harvard University. He is generall ...

(1863–1949) *

Albert Spear Hitchcock Albert Spear Hitchcock (September 4, 1865 – December 16, 1935) was an American botanist and agrostologist. Hitchcock graduated from the Iowa Agricultural College with bachelor's degree in 1884 and M.S. in 1886. From 1892 to 1901 he was a prof ...

(1865–1935) * Charles Piper (1867–1926) * Willis Lynn Jepson (1867–1946) * John Kunkel Small (1869–1938) *

Mary Agnes Chase Mary Agnes Chase (1869–1963) was an American botanist who specialized in agrostology, the study of grasses. Although lacking formal education past elementary school, Chase was able to rise through the ranks as a botanist at the United States D ...

(1869–1963) * Merritt Lyndon Fernald (1873–1950) * LeRoy Abrams (1874–1956) * Henry Allan Gleason (1882–1975) *

Paul Carpenter Standley Paul Carpenter Standley (March 21, 1884 – June 2, 1963) was an American botanist known for his work on neotropical plants. __TOC__ Standley was born on March 21, 1884 in Avalon, Missouri. He attended Drury College in Springfield, Missouri a ...

(1884–1963) *

Edgar Theodore Wherry Edgar Theodore Wherry (1885–1982) was an American mineralogist, soil scientist and botanist. He had a deep interest in ferns and ''Sarracenia''. Wherry earned his bachelor's degree in chemistry in 1906 from the University of Pennsylvania. He ...

(1885–1982) * Earl Edward Scherff (1886–1966) * Emma Lucy Braun (1889–1971) *

Philip Alexander Munz Philip Alexander Munz (1892–1974) was an American botanist, plant taxonomist and educator who worked at the Rancho Santa Ana Botanic Garden and was a professor of botany at Pomona College, serving as dean there for three years. In 1935 Munz pub ...

(1892–1974) * Harold St. John (1892–1991) * Eric Hultén (1894–1981) * Ivan Murray Johnston (1898–1960) *

Charles Leo Hitchcock Charles Leo Hitchcock (April 23, 1902 – February 3, 1986) was an American botanist. He discovered 20 species of plants and his works have been cited thousands of times. He is also the primary co-author to the Flora of the Pacific Northwest ...

(1902–1986) *

Frederick Joseph Hermann Frederick may refer to: People * Frederick (given name), the name Nobility Anhalt-Harzgerode *Frederick, Prince of Anhalt-Harzgerode (1613–1670) Austria * Frederick I, Duke of Austria (Babenberg), Duke of Austria from 1195 to 1198 * Frederick ...

(1906–1987) *

George Ledyard Stebbins George Ledyard Stebbins Jr. (January 6, 1906 – January 19, 2000) was an American botanist and geneticist who is widely regarded as one of the leading evolutionary biologists of the 20th century. Stebbins received his Ph.D. in botany from Ha ...

(1906–2000) * Elbert Luther Little, Jr. (1907–2004) * Julian Alfred Steyermark (1909–1988) *

Lyman David Benson Lyman David Benson (1909–1993) was an American botanist and author of Taxon names. He established roughly 500 names for cacti as well as 14 other taxon names. File:Lyman_Benson.jpg Works * 1957. Plant Classification. Ed. Heath, Boston. 688 pa ...

(1909–1993) *

Reed Clark Rollins Reed Clark Rollins (7 December 191128 April 1998) was an American botanist, professor at Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College ...

(1911–1998) * Rupert Charles Barneby (1911–2000) * Albert Ernest Radford (1918–2006) * Warren Herbert Wagner (1920–2000) * William Alfred Weber (b. 1918) * Arthur Cronquist (1919–1992) * Ronald Leighton McGregor (born 1919) * Carlyle August Luer (born 1922) *

Robert Kral Robert Joseph Kral (born 5 July 1967) is an Australian film and television composer. He is best known for composing music scores for horror, superhero, and many animated WB productions. He scored the TV series, ''Angel (1999 TV series), Angel'' ...

(born 1926) * Stanley Larson Welsh (born 1928) *

George William Argus George may refer to: People * George (given name) * George (surname) * George (singer), American-Canadian singer George Nozuka, known by the mononym George * George Washington, First President of the United States * George W. Bush, 43rd Preside ...

(born 1929) *

Edward Groesbeck Voss Edward Groesbeck "Ed" Voss (February 22, 1929 – February 13, 2012) was an American botanist and expert on taxonomic nomenclature. Voss was born in Delaware, Ohio, received his Ph.D. degree from the University of Michigan in 1954 and spen ...

(1929–2012) *

James Lauritz Reveal James Lauritz Reveal (March 29, 1941 – January 9, 2015) was a U.S. botanist best known for his contributions to the genus ''Eriogonum'' and for his work on suprageneric names. His website, at PlantSystematics.org, also presents material on plan ...

(1941–2015) * Anton Alfred Reznicek (born 1950) *

Warren Lambert Wagner Warren Lambert Wagner (born February 8, 1950, Las Cruces, New Mexico) is an American botanist, a curator of botany, and a leading expert on Onagraceae and plants of the Pacific Islands, (with links to Wagner's articles and books) especially plants ...

(born 1950) *

Barbara Jean Ertter Barbara may refer to: People * Barbara (given name) * Barbara (painter) (1915–2002), pseudonym of Olga Biglieri, Italian futurist painter * Barbara (singer) (1930–1997), French singer * Barbara Popović (born 2000), also known mononymously as ...

(born 1953) * John Thomas Kartesz

Divisions

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

Further reading