''Helianthus'' () is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

comprising about 70

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 ...

of annual and perennial

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s in the daisy 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 ...

commonly known as sunflowers. Except for three

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

n species, the species of ''Helianthus'' are native to

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 ...

and

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

. The best-known species is the

common sunflower The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), as ...

(''Helianthus annuus''), whose round flower heads in combination with the

ligules A ligule (from "strap", variant of ''lingula'', from ''lingua'' "tongue") is a thin outgrowth at the junction of leaf and leafstalk of many grasses (Poaceae) and sedges. A ligule is also a strap-shaped extension of the corolla, such as that of a ...

look like the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. This and other species, notably

Jerusalem artichoke The Jerusalem artichoke (''Helianthus tuberosus''), also called sunroot, sunchoke, wild sunflower, topinambur, or earth apple, is a species of sunflower native to central North America. It is cultivated widely across the temperate zone for its ...

(''H. tuberosus''), are cultivated in

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 ...

regions and some

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

regions, as food crops for humans, cattle, and poultry, and as ornamental plants. The species ''H. annuus'' typically grows during the summer and into early fall, with the peak growth season being mid-summer. Several

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

''Helianthus'' species are grown in gardens, but have a tendency to spread rapidly and can become aggressive. On the other hand, the whorled sunflower, ''Helianthus verticillatus'', was listed as an

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

species in 2014 when the

U.S. Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with oth ...

issued a final rule protecting it under the

Endangered Species Act The Endangered Species Act of 1973 (ESA or "The Act"; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of ec ...

. The primary threats are industrial forestry and

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...

plantations in Alabama, Georgia, and Tennessee. They grow to and are primarily found in woodlands, adjacent to creeks and moist, prairie-like areas. The common sunflower is the national flower of

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...

, cultivated there for several centuries.

Description

Sunflowers are usually tall

annual Annual may refer to: * Annual publication, periodical publications appearing regularly once per year **Yearbook ** Literary annual * Annual plant * Annual report * Annual giving * Annual, Morocco, a settlement in northeastern Morocco * Annuals (b ...

or perennial plants that in some species can grow to a height of or more. Each "flower" is actually a disc made up of tiny flowers, to form a larger false flower to better attract pollinators. The plants bear one or more wide, terminal capitula (flower heads made up of many tiny flowers), with bright yellow ray

florets 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 ...

(mini flowers inside a flower head) at the outside and yellow or maroon (also known as a brown/red) disc florets inside. Several ornamental

cultivars A cultivar is a type of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and when Plant propagation, propagated retain those traits. Methods used to propagate cultivars include: division, root and st ...

of '' H. annuus'' have red-colored ray florets; all of them stem from a single original mutant. While the majority of sunflowers are yellow, there are branching varieties in other colours including, orange, red and purple. The

petiolate Petiole may refer to: *Petiole (botany), the stalk of a leaf, attaching the blade to the stem *Petiole (insect anatomy) In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, a ...

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

are dentate and often sticky. The lower leaves are opposite,

ovate Ovate may refer to: *Ovate (egg-shaped) leaves, tepals, or other botanical parts *Ovate, a type of prehistoric stone hand axe *Ovates, one of three ranks of membership in the Welsh Gorsedd *Vates In modern English, the nouns vates () and ovat ...

, or often heart-shaped. The rough and hairy

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

is branched in the upper part in wild plants, but is usually unbranched in domesticated cultivars. This genus is distinguished technically by the fact that the ray florets (when present) are sterile, and by the presence on the disk flowers of a pappus that is of two awn-like scales that are

caducous Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part; structures that op ...

(that is, easily detached and falling at maturity). Some species also have additional shorter scales in the pappus, and one species lacks a pappus entirely. Another technical feature that distinguishes the genus more reliably, but requires a microscope to see, is the presence of a prominent, multicellular appendage at the apex of the style. Further, the florets of a sunflower are arranged in a natural

spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:H. radula'', lacks ray flowers altogether. Overall, the macroevolution of the ''Helianthus'' is driven by multiple biotic and abiotic factors and influences various floral morphology. ''Helianthus'' species are used as food plants by the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e of many lepidopterans.

Growth stages

The growth of a sunflower depends strictly on its genetic makeup and background. Additionally, the season it is planted will have effects on its development; those seasons tend to be in the middle of summer and beginning of fall. Sunflower development is classified by a series of vegetative stages and reproductive stages that can be determined by identifying the heads or main branch of a single head or branched head. Helianthus whorl

Phylogeny

The geographical history of this genus accounts for its evolutionary history, with its levels of genetic variation across its gene pool increasing as new hybrids are created both for commercial use and in the wild. As a result, sunflower species are also experiencing a genetic bottleneck as a result of selective breeding for industrial use.

Facing the sun (heliotropism)

Before blooming, ''Helianthus'' plant heads tilt during the day to face the

sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. This movement is referred to as

heliotropism Heliotropism, a form of tropism, is the diurnal or seasonal motion of plant parts (flowers or leaves) in response to the direction of the Sun. The habit of some plants to move in the direction of the Sun, a form of tropism, was already known by t ...

, which continues for a short time when flower buds form and young ''Helianthus'' heads track the Sun. At night, the flower heads reorient their position and face East in anticipation for the sunrise. Sunflowers move back to their original position between 3am and 6am, and the leaves follow about an hour later. By the time they are mature and reach

anthesis Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period. The onset of anthesis is spectacular in some species. In ''Banksia'' species, for example, anthesis involves the extension ...

, ''Helianthus'' generally stop moving and remain facing east, which lets them be warmed by the rising sun. Historically, this has led to controversy on whether or not ''Helianthus'' is heliotropic, as many scientists have failed to observe movement when studying plants that have already bloomed. This is notably different from heliotropism in leaves, as the moving mechanism for leaves exists in the

pulvinus A pulvinus (pl. ''pulvini'') is a joint-like thickening at the base of a plant leaf or leaflet that facilitates growth-independent movement. Pulvini are common, for example, in members of the bean family Fabaceae (Leguminosae) and the prayer plant ...

. Since flowers do not have pulvini, the movement is caused by increased growth rate of the stems. The growth rate accumulation of the stem on the east side of the stem gradually pushes the flower from east to west during daytime. This matches with the sun as it rises from the east and falls in the west. At night, the growth rate is higher in the west side of the stem that gradually pushes the flower from the west side back to the east side. In addition, it is not actually the whole plant that changes its direction to face the sun, but the flower itself that bends to be illuminated by the sun rays. The heliotropic movement is caused by growth on the opposite side of the flower, driven by accumulation of growth hormones during Sun exposure. Heliotropism persists on cloudy days when the sun is not shining brightly, meaning that the movement is

endogenous Endogenous substances and processes are those that originate from within a living system such as an organism, tissue, or cell. In contrast, exogenous substances and processes are those that originate from outside of an organism. For example, es ...

as a trained and continuous process. However, flower movement does not occur during long periods of rain or clouds. It also does not occur in a growth chamber when exposed to 16 hours of light or in greenhouses, suggesting that the plants require a directional, moving light source. Helianthus can also discriminate between different types of light. When exposed to different light frequencies, the

hypocotyl The hypocotyl (short for "hypocotyledonous stem", meaning "below seed leaf") is the stem of a germinating seedling, found below the cotyledons (seed leaves) and above the radicle (root). Eudicots As the plant embryo grows at germination, it send ...

s will bend toward blue light but not red light, depending on the quality of the light source. It is the circadian rhythms and the differences of the stem growth rate that work together and cause the heliotropism of the ''Helianthus''. This is important for attracting pollinators and increasing growth metabolism. Future studies are needed for identifying the exact physiological basis and cellular mechanism for this behavior.

Taxonomy

There are many species recognized in the genus: * ''

Helianthus agrestis ''Helianthus agrestis'' is a species of Helianthus, sunflower known by the common name southeastern sunflower. It is one of 150 sunflower species in the genus ''Helianthus''. It is found only in the states of Florida and Georgia in the southeaste ...

'' Pollard – southeastern sunflower –

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, and to ...

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

* '' Helianthus ambiguus'' Britt. –

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

* ''

Helianthus angustifolius ''Helianthus angustifolius'' is a species of Helianthus, sunflower known by the common name narrowleaf sunflower or swamp sunflower. It is native to the south-central and eastern United States, found in all the coastal states from Texas to Long I ...

'' L. – swamp sunflower –

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 ...

, northern

to southern

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

Long Island Long Island is a densely populated island in the southeastern region of the U.S. state of New York (state), New York, part of the New York metropolitan area. With over 8 million people, Long Island is the most populous island in the United Sta ...

, New York * ''

Helianthus annuus The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), as b ...

'' L. – common sunflower, ''girasol'' – most of United States + Canada * '' Helianthus anomalus'' S.F.Blake – western sunflower –

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

* '' Helianthus argophyllus'' Torr. & A.Gray – silverleaf sunflower –

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

* ''

Helianthus arizonensis ''Helianthus arizonensis'' is a North American species of sunflower known by the common name Arizona sunflower. It is native to the States of Arizona and New Mexico in the southwestern United States. ''Helianthus arizonensis'' is a perennial he ...

'' R.C.Jacks. – Arizona sunflower – Arizona, New Mexico * ''

Helianthus atrorubens ''Helianthus atrorubens'' is a North American species of Helianthus, sunflower known by the common name purpledisc sunflower. It is native to the southeastern United States. It is found in all the coastal states from Louisiana to Virginia, plus t ...

'' L. – purpledisk sunflower –

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Al ...

, Georgia, Florida,

South Carolina )''Animis opibusque parati'' ( for, , Latin, Prepared in mind and resources, links=no) , anthem = " Carolina";" South Carolina On My Mind" , Former = Province of South Carolina , seat = Columbia , LargestCity = Charleston , LargestMetro = ...

, North Carolina,

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virginia to ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

* ''

Helianthus bolanderi ''Helianthus bolanderi'' is a species of Helianthus, sunflower known by the common names Bolander's sunflower and serpentine sunflower. It is native to California and Oregon, where it grows mainly in mountainous areas, often in serpentine soils. ...

'' A.Gray – serpentine sunflower –

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

* ''

Helianthus × brevifolius ''Helianthus'' () is a genus comprising about 70 species of annual and perennial flowering plants in the daisy family Asteraceae commonly known as sunflowers. Except for three South American species, the species of ''Helianthus'' are native to N ...

'' E.Watson – Texas,

Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...

, Ohio * ''

Helianthus californicus ''Helianthus californicus'' is a North American species of sunflower known by the common name California sunflower. It is native to California in the United States and Baja California in Mexico, where it grows in many types of habitats. ''Helian ...

'' DC. – California sunflower –

* '' Helianthus carnosus'' Small – lakeside sunflower – Florida * ''

Helianthus ciliaris ''Helianthus ciliaris'' is a species of sunflower known by the common names Texas blueweed and yerba parda. ''Helianthus ciliaris'' grows in much of the south-central and southwestern United States (from Texas north to Kansas and west to Califor ...

'' DC. – Texas blueweed – United States:

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

, California, Arizona, New Mexico, Nevada, Utah, Texas,

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...

, Illinois; Mexico:

Tamaulipas Tamaulipas (), officially the Free and Sovereign State of Tamaulipas ( es, Estado Libre y Soberano de Tamaulipas), is a state in the northeast region of Mexico; one of the 31 states which, along with Mexico City, comprise the 32 Federal Entiti ...

Coahuila Coahuila (), formally Coahuila de Zaragoza (), officially the Free and Sovereign State of Coahuila de Zaragoza ( es, Estado Libre y Soberano de Coahuila de Zaragoza), is one of the 32 states of Mexico. Coahuila borders the Mexican states of N ...

, Chihuahua,

Sonora Sonora (), officially Estado Libre y Soberano de Sonora ( en, Free and Sovereign State of Sonora), is one of the 31 states which, along with Mexico City, comprise the Administrative divisions of Mexico, Federal Entities of Mexico. The state is d ...

* '' Helianthus cinereus'' Small –

Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...

, Kentucky, Indiana, Ohio * '' Helianthus coloradensis'' Cockerell – prairie sunflower – Colorado, New Mexico * '' Helianthus cusickii'' A.Gray – Cusick's sunflower – Washington, Oregon, California,

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...

, Nevada * ''

Helianthus debilis ''Helianthus debilis'' is a species of sunflower known by the common names cucumberleaf sunflower, beach sunflower, weak sunflower, and East Coast dune sunflower.Wunderlin, R. P. and B. F. Hansen. 2008''Helianthus debilis''.''Atlas of Florida Va ...

'' Nutt. – cucumberleaf sunflower – Texas to

Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and north ...

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

* '' Helianthus decapetalus'' L. – thinleaf sunflower – eastern United States;

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...

* '' Helianthus deserticola'' Heiser – desert sunflower – Arizona, Nevada, Utah * †'' Helianthus diffusus'' Sims – Missouri† * '' Helianthus dissectifolius'' R.C.Jacks. – Mexico * ''

Helianthus divaricatus ''Helianthus divaricatus'', commonly known as the rough sunflower, woodland sunflower, or rough woodland sunflower,Dickinson, T.; Metsger, D.; Bull, J.; & Dickinson, R. (2004). ''ROM Field Guide to Wildflowers of Ontario.'' Toronto:Royal Ontario ...

'' L. – woodland sunflower or rough woodland sunflower – eastern United States; Ontario, Quebec * '' Helianthus × divariserratus'' R.W.Long Michigan, Indiana, Ohio,

Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its cap ...

* '' Helianthus × doronicoides'' Lam. – Texas,

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 ...

, Missouri,

Iowa Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to the ...

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...

, Illinois, Kentucky, Indiana, Ohio,

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

, Michigan,

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

, Virginia * '' Helianthus eggertii'' Small – Alabama, Kentucky, and Tennessee * '' Helianthus exilis'' A.Gray – California * ''

Helianthus floridanus ''Helianthus floridanus'' is a species of Helianthus, sunflower known by the common name Florida sunflower. It is native to the southeastern United States, found in all the coastal states from Alabama to North Carolina, plus Louisiana. ''Heliant ...

'' A.Gray ex Chapm. – Florida sunflower – Louisiana, Alabama, Georgia, Florida, South Carolina, North Carolina * ''

Helianthus giganteus ''Helianthus giganteus'', the giant sunflower or tall sunflower, is a species of ''Helianthus'' native to the eastern United States and eastern and central Canada, from Newfoundland west to Alberta south to Minnesota, Mississippi, and South Car ...

'' L. – giant sunflower – eastern United States; most of Canada * '' Helianthus glaucophyllus'' D.M.Sm – whiteleaf sunflower – Tennessee, South Carolina, North Carolina * '' Helianthus × glaucus'' Small – scattered locales in southeastern United States * '' Helianthus gracilentus'' A.Gray – slender sunflower – California * ''

Helianthus grosseserratus Helianthus grosseserratus, commonly known as sawtooth sunflower or thick-tooth sunflower, is a perennial sunflower in the family Asteraceae, with a large flowering head (inflorescence). The plant may reach 3–12 feet (91–366 cm) in heigh ...

'' M.Martens – sawtooth sunflower –

Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...

, Ontario, Quebec * '' Helianthus heterophyllus'' Nutt. – variableleaf sunflower – Coastal plain of Texas to North Carolina * ''

Helianthus hirsutus ''Helianthus hirsutus'' is a North American species of Helianthus, sunflower known by the common name hairy sunflower. It is widespread across south-central Canada, the eastern and central United States, and northeastern Mexico. It ranges from On ...

'' Raf. – hairy sunflower – central and eastern United States, Ontario * ''Helianthus'' × ''intermedius'' R.W.Long – intermediate sunflower – scattered locales in United States * '' Helianthus laciniatus'' A.Gray – alkali sunflower – United States: Arizona, New Mexico, Texas; Mexico:

Nuevo León Nuevo León () is a state in the northeast region of Mexico. The state was named after the New Kingdom of León, an administrative territory from the Viceroyalty of New Spain, itself was named after the historic Spanish Kingdom of León. With a ...

* ''Helianthus'' × ''laetiflorus'' Pers. – cheerful sunflower, mountain sunflower – scattered in eastern and central United States; Canada * '' Helianthus laevigatus'' Torr. & A.Gray – smooth sunflower – Georgia, South Carolina, North Carolina, Virginia, Maryland,

West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the Bur ...

* ''

Helianthus lenticularis The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), as ...

'' Douglas ex Lindl. California, Texas * '' Helianthus longifolius'' Pursh – longleaf sunflower – Alabama, Georgia, North Carolina * '' Helianthus × luxurians'' (E.Watson) E.Watson –

region * ''

Helianthus maximiliani ''Helianthus maximiliani'' is a North American species of sunflower known by the common name Maximilian sunflower. This sunflower is named for Prince Maximilian of Wied-Neuwied, who encountered it on his travels in North America. ''Helianthus m ...

'' Schrad. – Maximillian sunflower – much of United States and Canada * ''

Helianthus membranifolius ''Helianthus membranifolius'' is a species of sunflower in the family Asteraceae. It is native to Cayenne Island in French Guiana, part of the French Republic France (), officially the French Republic ( ), is a country primarily loc ...

'' Poir. –

French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas departments and regions of France, overseas department/region and single territorial collectivity of France on the northern Atlantic ...

* '' Helianthus microcephalus'' Torr. & A.Gray – eastern United States * '' Helianthus mollis'' Lam. – downy sunflower, ashy sunflower – Ontario, eastern and central United States * '' Helianthus multiflorus'' L. – manyflower sunflower – Ohio * ''

Helianthus navarri ''Helianthus navarri'' is a species of sunflower in the family Asteraceae. It is native to Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and ...

'' Phil. –

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

* ''

Helianthus neglectus ''Helianthus neglectus'' is a species of sunflower known by the common names neglected sunflower. It is native to the southwestern United States in southeastern New Mexico and West Texas. ''Helianthus neglectus'' grows on sand dunes and other sa ...

'' Heiser – neglected sunflower – New Mexico, Texas * ''

Helianthus niveus ''Helianthus niveus'' is a species of sunflower known by the common names showy sunflower and snowy sunflower. It is native to northern Mexico (Sonora, Baja California, Baja California Sur) and the Southwestern United States (Southern California, ...

'' (Benth.) Brandegee – showy sunflower – United States: California,

; Mexico:

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

Baja California Sur Baja California Sur (; 'South Lower California'), officially the Free and Sovereign State of Baja California Sur ( es, Estado Libre y Soberano de Baja California Sur), is the least populated state and the 31st admitted state of the 32 federal ent ...

* ''

Helianthus nuttallii ''Helianthus nuttallii'', or Nuttall's sunflower, is a species of sunflower native to northern, central, and western North America, from Newfoundland west to British Columbia, south to Missouri, New Mexico, and California. ''Helianthus nuttallii ...

'' Torr. & A.Gray – western and central United States, Canada * '' Helianthus occidentalis'' Riddell – fewleaf sunflower, western sunflower – Great Lakes region, scattered in southeastern United States * '' Helianthus × orgyaloides'' Cockerell – Colorado, Kansas * '' Helianthus paradoxus'' Heiser – paradox sunflower – Utah, New Mexico, Texas * '' Helianthus pauciflorus'' Nutt. – stiff sunflower – central United States, Canada * ''

Helianthus petiolaris ''Helianthus petiolaris'' is a North American plant species in the family Asteraceae, commonly known as the prairie sunflower or lesser sunflower. Naturalist and botanist Thomas Nuttall was the first to describe the prairie sunflower in 1821. Th ...

'' Nutt. – prairie sunflower, lesser sunflower – much of United States, Canada * '' Helianthus porteri'' (A.Gray) Pruski – Porter's sunflower – Alabama, Georgia, South Carolina, North Carolina * ''

Helianthus praecox ''Helianthus praecox'' is a North American species of sunflower known by the common name Texas sunflower. It is endemic to Texas. Most of the populations are either along the Gulf Coast or in the Río Grande Valley. ''Helianthus praecox'' grows ...

'' Engelm. & A.Gray Texas sunflower – Texas * †''

Helianthus praetermissus ''Helianthus praetermissus'' is a rare and probably extinct North American species of sunflower, with the common names New Mexico sunflower and lost sunflower. It is known from only one specimen collected in 1851 in Cibola County in western New M ...

'' – New Mexico sunflower – New Mexico† * '' Helianthus pumilus'' Nutt. – little sunflower – Colorado,

Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the south ...

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...

, Utah, Idaho * '' Helianthus radula'' (Pursh) Torr. & A.Gray – rayless sunflower – Louisiana, Mississippi, Alabama, Georgia, South Carolina, Florida * '' Helianthus resinosus'' Small – resindot sunflower – Mississippi, Alabama, Georgia, South Carolina, North Carolina, Florida * '' Helianthus salicifolius'' A.Dietr. – willowleaf sunflower – Texas, Oklahoma, Kansas, Missouri, Illinois, Wisconsin, Ohio, Pennsylvania, New York * ''

Helianthus sarmentosus ''Helianthus sarmentosus'' is a species of Helianthus, sunflower in the family Asteraceae. It is native to French Guiana, part of the French Republic. 29: 492] in French, as ''Chylodia sarmentosa'' References

Helianthus, sarmentosus Flor ...

'' Rich. – French Guiana * ''

Helianthus scaberrimus ''Helianthus'' () is a genus comprising about 70 species of annual and perennial flowering plants in the daisy family Asteraceae commonly known as sunflowers. Except for three South American species, the species of ''Helianthus'' are native to N ...

'' Elliott – South Carolina * ''

Helianthus schweinitzii ''Helianthus schweinitzii'' is a perennial wildflower endemic to the Piedmont physiographic province of North Carolina and South Carolina. Its common name is Schweinitz's sunflower. It is a member of the sunflower family (Asteraceae). It is one ...

'' Torr. & A.Gray – Schweinitz's sunflower – South Carolina, North Carolina * '' Helianthus silphioides'' Nutt. – rosinweed sunflower –

Lower Mississippi Valley The Mississippi River Alluvial Plain is an alluvial plain created by the Mississippi River on which lie parts of seven U.S. states, from southern Louisiana to southern Illinois (Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, Lou ...

* ''

Helianthus simulans ''Helianthus simulans'' is a North American species of sunflower known by the common name muck sunflower. It is native to the southeastern and south-central United States, from eastern Texas to the Carolinas. There are some suggestions that the p ...

'' E.Watson – muck sunflower – southeastern United States * '' Helianthus smithii'' Heiser – Smith's sunflower – Alabama, Georgia, Tennessee * '' Helianthus speciosus'' Hook. –

Michoacán Michoacán, formally Michoacán de Ocampo (; Purépecha: ), officially the Free and Sovereign State of Michoacán de Ocampo ( es, Estado Libre y Soberano de Michoacán de Ocampo), is one of the 32 states which comprise the Federal Entities of ...

* '' Helianthus strumosus'' L. – eastern and central United States, Canada * ''

Helianthus subcanescens ''Helianthus'' () is a genus comprising about 70 species of annual and perennial flowering plants in the daisy family Asteraceae commonly known as sunflowers. Except for three South American species, the species of ''Helianthus'' are native to N ...

'' (A.Gray) E.Watson –

Manitoba Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...

, north-central United States * '' Helianthus subtuberosus'' Bourg. * ''

Helianthus tuberosus The Jerusalem artichoke (''Helianthus tuberosus''), also called sunroot, sunchoke, wild sunflower, topinambur, or earth apple, is a species of sunflower native to central North America. It is cultivated widely across the temperate zone for its ...

'' L. – Jerusalem artichoke, sunchoke, earth-apple, topinambur – much of United States and Canada * ''

Helianthus verticillatus ''Helianthus'' () is a genus comprising about 70 species of annual and perennial flowering plants in the daisy family Asteraceae commonly known as sunflowers. Except for three South American species, the species of ''Helianthus'' are native to ...

'' Small – whorled sunflower – Alabama, Georgia, Tennessee

Formerly included

The following species were previously included in the genus ''Helianthus''. * '' Flourensia thurifera'' (Molina) DC. (as ''H. thurifer'' Molina) * ''

Helianthella quinquenervis ''Helianthella quinquenervis'', the fivenerve helianthella, is a North American plant species in the family Asteraceae. It grows in the mountains of the western United States and northern Mexico. This include the Rockies, the Black Hills, the ran ...

'' (Hook.) A.Gray (as ''H. quinquenervis'' Hook.) * ''

Helianthella uniflora ''Helianthella uniflora'', the oneflower helianthella, is a North American plant species in the family Asteraceae. It grows in the western United States and western Canada. It has been found from British Columbia south as far as northern Arizona ...

'' (Nutt.) Torr. & A.Gray (as ''H. uniflorus'' Nutt.) * '' Pappobolus imbaburensis'' (Hieron.) Panero (as ''H. imbaburensis'' Hieron.) * '' Viguiera procumbens'' (Pers.) S.F.Blake (as ''H. procumbens'' Pers.)

Uses

The

seeds A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm pl ...

of ''H. annuus'' are used as human food. Most

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...

s of sunflower are variants of ''H. annuus'', but four other species (all

s) are also domesticated. This includes ''H. tuberosus'', the

, which produces edible tubers. There are many species in the sunflower genus ''Helianthus'', and many species in other genera that may be called sunflowers. * The Maximillian sunflower (''

'') is one of 38 species of

perennial sunflower Perennial sunflower is a crop of sunflowers that are developed by crossing wild Perennial plant, perennial and domestic annual sunflower species. Annual sunflower is a major oilseed crop. Genes from wild perennial relatives may increase root dept ...

native to

. The

Land Institute The Land Institute is an American nonprofit A nonprofit organization (NPO) or non-profit organisation, also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated fo ...

and other breeding programs are currently exploring the potential for these as a perennial seed crop. * The sunchoke (

or ''Helianthus tuberosus'') is related to the sunflower, another example of

. * The Mexican sunflower is '' Tithonia rotundifolia''. It is only very distantly related to North American sunflowers. * False sunflower refers to plants of the genus '' Heliopsis''.

Ecology

Sunflowers have been proven to be excellent plants to attract beneficial insects, including pollinators. ''Helianthus spp.'' are a nectar producing flowering plant that attract pollinators and parasitoids which reduce the pest populations in nearby crop vegetation. Sunflowers attract different beneficial pollinators (e.g., honey bees) and other known insect prey to feed on and control the population of parasitic pests that could be harmful to the crops. Predacious insects are first attracted to sunflowers once they are planted. Once the ''Helianthus spp.'' reaches six inches and produces flowers it begins to attract more pollinators. Distance between sunflower rows and crop vegetation plays an important role in this phenomenon, hypothesizing that closer proximity to the crops will increase insect attraction. In addition to pollinators of ''Helianthus spp''., there are other factors such as abiotic stress, florivory, and disease which also contribute to the evolution of floral traits. These selective pressures, which stem from several biotic and abiotic factors are associated with habitat environmental conditions which all play a role in the overall morphology of the sunflowers’ floral traits. An ecosystem is composed of both biotic (which are living elements of an ecosystem such as plants, animals, fungi, protists, and bacteria), and abiotic factors (non-living elements of an ecosystem such as air, soil, water, light, salinity and temperature). It is thought that two biotic factors can explain for the evolution of larger sunflowers and why they are present in more drier environments. For one thing, the selection by pollinators is thought to have increased the sunflower’s size in a drier environment. This is because in a drier environment, there are typically less pollinators. As a result, in order for the sunflower to be able to attract more pollinators, they had to increase the morphology of their floral traits in that they had to increase their display size. Another biotic factor that can explain for the evolution of larger sunflowers in drier environments is that the pressure from florivory and disease favors smaller flowers in habitats that have a more moderate supply of moisture (mesic habitat). Wetter environments usually have more dense vegetation, more herbivores, and more surrounding pathogens. As larger flowers are typically more susceptible to disease and florivory, smaller flowers may have evolved in wetter environments which explains the evolution of larger sunflowers in more drier environments.

Gallery

File:Sunflower_Kamand_DSC_2856.jpg, Close-up of a sunflower head File:Helianthus decapetalus 'Plenus'.jpg, ''Helianthus decapetalus''
"Plenus" File:Helianthus petiolaris (7161930155).jpg,

Prairie sunflower ''Helianthus petiolaris'' is a North American plant species in the family Asteraceae, commonly known as the prairie sunflower or lesser sunflower. Naturalist and botanist Thomas Nuttall was the first to describe the prairie sunflower in 1821. Th ...

(''H. petiolaris'') File:Helianthus giganteus.jpg, Giant sunflower
(''H. giganteus'') File:HelianthusTuberosus.jpg,

(''H. tuberosus'') File:Helianthus x laetiflorus 001.JPG, ''H. laetiflorus'' File:Helianthus orgyalis0.jpg, Willowleaf sunflower
(''H. salicifolius'') File:Helianthus annuus - flower view 01.jpg, ''H. annuus'' File:Red sunflower.jpg, An orange-red sunflower File:Redeed.jpg, A dark red sunflower cultivar File:Sunflower "Strawberry Blonde" (3931552086).jpg, ''Helianthus''
'Strawberry Blonde' File:Flower bud of Sunflower - Helianthus.JPG, Sunflower bud File:Side rear view of Sunflower head- Helianthus.JPG, Rear view of a sunflower head File:Sunflower Leaf- Helianthus.JPG, Leaves of a sunflower plant File:Sunflower leaf structure.jpg, Sunflower leaf structure File:Семечко подсолнечника.jpg, Seed under a microscope

References

{{Taxonbar, from=Q26949 Asteraceae genera Flora of North America Crops Taxa named by Carl Linnaeus Crops originating from indigenous Americans

Description

Growth stages

Phylogeny

Facing the sun (heliotropism)

Taxonomy

Formerly included

Uses

Ecology

Gallery

See also

References