''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

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. The best-known species is the common sunflower (''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. This and other species, notably Jerusalem artichoke (''H. tuberosus''), are cultivated in temperate regions and some tropical 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 ''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 species in 2014 when the U.S. Fish and Wildlife Service 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 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, cultivated there for several centuries.

Description

Sunflowers are usually tall annual 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 (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 larvae 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. 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 hypocotyls 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, Georgia * ''

Helianthus ambiguus ''Helianthus ambiguus'' is a North American species of sunflower known by the common name ambiguous sunflower. It is found only in the Great Lakes region of the United States, the states of New York, Michigan, Ohio, and Wisconsin Wisconsi ...

'' Britt. – Wisconsin, Michigan, Ohio,

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, northern Florida to southern Illinois,

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 ''Helianthus anomalus'', the western sunflower, is a species of plants in the family Asteraceae, found in the southwestern United States. ''Helianthus anomalus'' is of particular interest due to its genetics. It was produced via hybridization of ...

'' S.F.Blake – western sunflower – Nevada, Utah, Arizona, New Mexico * '' Helianthus argophyllus'' Torr. & A.Gray – silverleaf sunflower – Texas, North Carolina, Florida * ''

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 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 the inland s ...

'' L. – purpledisk sunflower – Louisiana, Alabama, Georgia, Florida, South Carolina, North Carolina, Tennessee, Kentucky, Virginia * ''

Helianthus bolanderi ''Helianthus bolanderi'' is a species of 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. It has been ...

'' A.Gray – serpentine sunflower – California, Oregon * ''

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, Ohio * '' Helianthus californicus'' DC. – California sunflower – California * ''

Helianthus carnosus ''Helianthus carnosus'' is a rare North American species of sunflower known by the common name lakeside sunflower. It is found only in the northeastern part of the state of Florida in the United States. ''Helianthus carnosus'' is a perennial her ...

'' 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, 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, Kansas, Illinois; Mexico: Tamaulipas,

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 Chihuahua may refer to: Places *Chihuahua (state), a Mexican state **Chihuahua (dog), a breed of dog named after the state **Chihuahua cheese, a type of cheese originating in the state **Chihuahua City, the capital city of the state **Chihuahua Mun ...

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 ''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 ...

'' Small – Missouri, Kentucky, Indiana, Ohio * '' Helianthus coloradensis'' Cockerell – prairie sunflower – Colorado, New Mexico * ''

Helianthus cusickii ''Helianthus cusickii'' is a species of sunflower known by the common names Cusick's sunflower and turniproot sunflower. It is native to the western United States from Washington, Oregon, Idaho, northern California, and northwestern Nevada. ''He ...

'' A.Gray – Cusick's sunflower – Washington, Oregon, California, Idaho, 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, Mississippi * ''

Helianthus decapetalus ''Helianthus decapetalus'', known by the common names thinleaf sunflower and thin-leaved sunflower, is a perennial forb in the family Asteraceae. It is native to the Eastern and Central United States and Canada, from New Brunswick west to Iowa, W ...

'' L. – thinleaf sunflower – eastern United States; Ontario, Quebec * ''

Helianthus deserticola ''Helianthus deserticola,'' the desert sunflower, is a plant species native to Arizona, 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, ...

'' Heiser – desert sunflower – Arizona, Nevada, Utah * †''

Helianthus diffusus ''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 ...

'' Sims – Missouri† * ''

Helianthus dissectifolius ''Helianthus dissectifolius'' is a rare species of sunflower, 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 a ...

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

, Arkansas, Missouri, Iowa, Minnesota, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, Michigan, New Jersey, Virginia * ''

Helianthus eggertii ''Helianthus eggertii'', known as Eggert's sunflower, is a North American species of flowering plants in the family Asteraceae. It is native to Tennessee, Kentucky, South Carolina, and Alabama. It is best known as one of the few plants to have be ...

'' Small – Alabama, Kentucky, and Tennessee * ''

Helianthus exilis ''Helianthus exilis'' is a species of sunflower known by the common name serpentine sunflower. It is endemic to northern California (from Siskiyou County south to Napa County and Nevada County), where it grows mainly in mountainous areas, often ...

'' A.Gray – California * '' Helianthus floridanus'' 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 ''Helianthus glaucophyllus'' is a species of sunflower known by the common name whiteleaf sunflower. It is native to the southeastern United States, in the southern Appalachian Mountains in North Carolina, Tennessee, and South Carolina, in and n ...

'' D.M.Sm – whiteleaf sunflower – Tennessee, South Carolina, North Carolina * ''

Helianthus × glaucus ''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 ...

'' Small – scattered locales in southeastern United States * ''

Helianthus gracilentus ''Helianthus gracilentus'' is a species of sunflower known by the common name slender sunflower. It is native to central and southern California (from Napa County to San Diego County) and Baja California, where it is a member of the dry wildfire- ...

'' A.Gray – slender sunflower – California * '' Helianthus grosseserratus'' 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, Ontario, Quebec * ''

Helianthus heterophyllus ''Helianthus heterophyllus'' is a species of sunflower known by the common names variableleaf sunflower and wetland sunflower. It is native to the coastal plain of the southern United States from Texas to North Carolina. ''Helianthus heterophyll ...

'' Nutt. – variableleaf sunflower – Coastal plain of Texas to North Carolina * ''

Helianthus hirsutus ''Helianthus hirsutus'' is a North American species of 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 Ontario south ...

'' Raf. – hairy sunflower – central and eastern United States, Ontario * ''Helianthus'' × ''intermedius'' R.W.Long – intermediate sunflower – scattered locales in United States * ''

Helianthus laciniatus ''Helianthus laciniatus'' is a North American species of sunflower known by the common name alkali sunflower. It is found in the southwestern United States (southeastern Arizona, southern New Mexico, western Texas) and north-central Mexico ( Chih ...

'' 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 ''Helianthus laevigatus'' is a North American species of sunflower known by the common name smooth sunflower. It is native to the east-central and southeastern United States from Georgia to Maryland. ''Helianthus laevigatus'' is a perennial he ...

'' Torr. & A.Gray – smooth sunflower – Georgia, South Carolina, North Carolina, Virginia, Maryland, West Virginia * ''

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

'' Douglas ex Lindl. California, Texas * ''

Helianthus longifolius ''Helianthus longifolius'' is a North American species of sunflower known by the common name longleaf sunflower. It is native to the southeastern United States (mostly Georgia and Alabama with one isolated population (probably introduced) in wes ...

'' Pursh – longleaf sunflower – Alabama, Georgia, North Carolina * ''

Helianthus × luxurians ''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) E.Watson – Great Lakes 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'' Poir. – French Guiana * ''

Helianthus microcephalus ''Helianthus microcephalus'' is a perennial species of ''Helianthus'' also known as small woodland sunflower or small-wood sunflower or small-head sunflower or simply as woodland sunflower. It is a native of Northern America, and is to be found g ...

'' Torr. & A.Gray – eastern United States * ''

Helianthus mollis ''Helianthus mollis'' is a species of sunflower known by the common names ashy sunflower, hairy sunflower or downy sunflower. It is widespread across much of the United States and Canada, primarily the Great Lakes region from Ontario south to Te ...

'' Lam. – downy sunflower, ashy sunflower – Ontario, eastern and central United States * ''

Helianthus multiflorus 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 ...

'' 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 * ''

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, Arizona; Mexico: Baja California,

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 ''Helianthus occidentalis'', the fewleaf sunflower or western sunflower, is a species of sunflower native to the Eastern and Central United States. It grows mostly in the Great Lakes Region and in the Ozarks, with additional populations scattered ...

'' Riddell – fewleaf sunflower, western sunflower – Great Lakes region, scattered in southeastern United States * ''

Helianthus × orgyaloides ''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 ...

'' Cockerell – Colorado, Kansas * ''

Helianthus paradoxus ''Helianthus paradoxus'', the paradox sunflower, puzzle sunflower or Pecos sunflower, is a threatened species of sunflower found only in west Texas, Utah, and New Mexico salt marshes by the edges of inland salt lakes and salt flats. ''Helianthus ...

'' Heiser – paradox sunflower – Utah, New Mexico, Texas * ''

Helianthus pauciflorus ''Helianthus pauciflorus'', called the stiff sunflower, is a North American plant species in the family Asteraceae. It is widespread across the Great Plains, the Rocky Mountains, and the Great Lakes region, and naturalized in scattered locations ...

'' Nutt. – stiff sunflower – central United States, Canada * '' Helianthus petiolaris'' Nutt. – prairie sunflower, lesser sunflower – much of United States, Canada * ''

Helianthus porteri ''Helianthus porteri'' is a species of sunflower known by the common names Porter's sunflower, Stone Mountain daisy and Confederate daisy. The term "daisy" is a imprecise because the species is a sunflower (''Helianthus'') rather than a daisy (' ...

'' (A.Gray) Pruski – Porter's sunflower – Alabama, Georgia, South Carolina, North Carolina * '' Helianthus praecox'' 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 ''Helianthus pumilus'' is a North American species of sunflower known by the common name little sunflower or bush sunflower. It is found in the western United States, primarily the Rocky Mountain region of Montana, Wyoming, and Colorado, with a f ...

'' Nutt. – little sunflower – Colorado, Wyoming, Montana, Utah, Idaho * ''

Helianthus radula ''Helianthus radula'' is a North American species of sunflower known by the common name rayless sunflower or pineland sunflower. It is native to the southeastern United States from eastern Louisiana to South Carolina. ''Helianthus radula'' grows ...

'' (Pursh) Torr. & A.Gray – rayless sunflower – Louisiana, Mississippi, Alabama, Georgia, South Carolina, Florida * ''

Helianthus resinosus ''Helianthus resinosus'' is a North American species of sunflower known by the common name sunflower. It is native to the southeastern United States from Mississippi to North Carolina. ''Helianthus resinosus '' grows in open swamps and meadows, ...

'' Small – resindot sunflower – Mississippi, Alabama, Georgia, South Carolina, North Carolina, Florida * ''

Helianthus salicifolius ''Helianthus salicifolius'' is a North American species of sunflower known by the common name willowleaf sunflower. It is native to the central United States, primarily in the Great Plains and Ozark Plateau (states of Missouri, Kansas, Oklahom ...

'' A.Dietr. – willowleaf sunflower – Texas, Oklahoma, Kansas, Missouri, Illinois, Wisconsin, Ohio, Pennsylvania, New York * '' Helianthus sarmentosus'' 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'' Torr. & A.Gray – Schweinitz's sunflower – South Carolina, North Carolina * ''

Helianthus silphioides ''Helianthus silphioides'' is a North American species of sunflower known by the common names rosinweed sunflower or Ozark sunflower. It is native to the central United States, primarily in the Ozarks and the Tennessee Valley with additional popu ...

'' Nutt. – rosinweed sunflower – Lower Mississippi Valley * '' Helianthus simulans'' E.Watson – muck sunflower – southeastern United States * ''

Helianthus smithii ''Helianthus smithii'' is a rare North American species of sunflower known by the common name Smith's sunflower. It is native to the southeastern United States, in Tennessee, Alabama, and Georgia. ''Helianthus smithii'' grows in wet, mucky soils ...

'' Heiser – Smith's sunflower – Alabama, Georgia, Tennessee * ''

Helianthus speciosus ''Helianthus speciosus'' is a Mexican species of sunflower in the family Asteraceae, called the showy Mexican sunflower. It is native to the state of Michoacán in western Mexico.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 ''Helianthus strumosus'', the pale-leaf woodland sunflower, is a species of sunflower native to North America east of the Great Plains and is in the family Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,00 ...

'' 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, north-central United States * ''

Helianthus subtuberosus ''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 Caro ...

'' 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 ''Flourensia'' is a genus of flowering plants in the family Asteraceae. It contains subshrubs and shrubs, which are commonly known as tarworts. They are found in the southwestern United States, Mexico, Central America, and South America. The genu ...

'' (Molina) DC. (as ''H. thurifer'' Molina) * '' Helianthella quinquenervis'' (Hook.) A.Gray (as ''H. quinquenervis'' Hook.) * '' Helianthella uniflora'' (Nutt.) Torr. & A.Gray (as ''H. uniflorus'' Nutt.) * ''

Pappobolus imbaburensis ''Pappobolus'' is a genus of flowering plant in the family Asteraceae native to the Andes Mountains of Colombia, Ecuador, and Peru. ''Pappobolus'' is distinguished from closely related genera by its combination of shrubby habit and usually caduc ...

'' (Hieron.) Panero (as ''H. imbaburensis'' Hieron.) * ''

Viguiera procumbens ''Viguiera'' is a genus of flowering plants in the family Asteraceae. The name honours French physician L. G. Alexandre Viguier (1790–1867). It contains around 150 species, which are commonly known as goldeneyes and are native to the New World ...

'' (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 cultivars of sunflower are variants of ''H. annuus'', but four other species (all perennials) are also domesticated. This includes ''H. tuberosus'', the Jerusalem artichoke, 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 ( Jerusalem artichoke or ''Helianthus tuberosus'') is related to the sunflower, another example of

. * The Mexican sunflower is ''

Tithonia ''Tithonia'' is a genus of flowering plants in the tribe Heliantheae within the family Asteraceae. ''Tithonia'' has a center of distribution in Mexico but with one species extending into the Southwestern United States and several native to Centr ...

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

Heliopsis ''Heliopsis'' is a genus of herbaceous flowering plants in the family Asteraceae, native to dry prairies in North and South America. The sunflower-like composite flowerheads are usually yellow, up to in diameter, and are borne in summer. Specie ...

''.

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