Derivation of specific name
General: Sunflower Family (Asteraceae). The sunflower is an erect, coarse, tap-rooted annual with rough-hairy stems 6-30 dm (2-10 ft) tall. The leaves are mostly alternate, egg-shaped to triangular, and entire or toothed. The flower heads are 7.5-15 cm (3-6 in) wide and at the ends of branches. Ray flowers are yellow and disk flowers are reddish-brown.
common sunflower, Kansas sunflower, mirasol; Helianthus comes from the Greek helios anthos, meaning “sun flower” (Kindscher 1987). The species name annuus means “annual.”
The sunflower (Helianthus annuus) is a common and widespread roadside weed. It is common in open sites in many different habitats throughout North America, southern Canada, and Mexico at elevations below 1900 m. Helianthus annuus is highly variable as a species, and hybridizes with several other species. The heads and plants are very large in cultivated forms.
Range and Habitat in Illinois
Regularity: Regularly occurring
Regularity: Regularly occurring
Range and Habitat in Illinois
Sunflowers need full sun. Irrigation is required until they become established.
Seed Propagation: When the soil has warmed up to at least 45ºF (7ºC) in the spring, sow hardy sunflower seeds where they are to flower. Seeds can also be sown in pots or seed trays and either planted out in their final positions in late fall or overwintered in a cold frame to be planted out in spring. This technique is particularly useful in gardens with clay soil that is slow to warm up in spring.
There are two main methods of sowing outdoors in situ: broadcast and in drills. For both, prepare the seedbed first. Dig over the soil to one spade’s depth, then rake over and firm. Broadcast Sowing: Sprinkle seeds thinly and evenly on the surface of the prepared seedbed and rake them in lightly. Label seedbeds, then water the area gently but thoroughly with a fine spray. Sowing in Drills: Using either a trowel tip or the corner of a hoe, mark out shallow drill holes 3-6” (8-15 cm) apart, depending on the ultimate size of the plant. Sow seeds thinly and evenly by sprinkling or placing them along each drill at the appropriate depth. Carefully cover with soil and firm. Label each row and water gently but thoroughly with a fine spray.
To prevent overcrowding, the seedlings usually need to be thinned. To minimize disturbance to a seedling being retained, press the soil around it after thinning the adjacent seedlings. Water the newly establishing seedlings fairly frequently until the roots have developed. Support is required for the sunflower stems. Stakes help support the stem and protect the seedlings from rodent or bird damage. Birds and small mammals love both the sunflower seeds and the tender young seedlings. A scarecrow or netting may be necessary to protect the plants from herbivores.
Flower-Visiting Insects of Annual Sunflower in Illinois
(Bees collect pollen or suck nectar; some flies and beetles feed on pollen
& are non-pollinating; other insects suck nectar; observations are from Robertson, LaBerge, Moure & Hurd, Hilty, Krombein et al., and Mawdsley)
Apidae (Apinae): Apis mellifera sn cp fq; Apidae (Bombini): Bombus bimaculatus sn, Bombus griseocallis sn fq, Bombus impatiens sn cp fq, Bombus pensylvanica sn cp fq, Bombus vagans, Psithyrus variabilis sn; Anthophoridae (Ceratini): Ceratina dupla dupla sn cp; Anthophoridae (Epeolini): Triepeolus concavus sn; Anthophoridae (Eucerini): Melissodes agilis sn cp fq olg, Melissodes bimaculata bimaculata (LB), Melissodes boltoniae sn cp fq, Melissodes coloradensis sn, Melissodes comptoides (LB), Melissodes dentiventris sn, Melissodes trinodis sn, Svastra atripes atripes (LB), Svastra obliqua obliqua sn cp fq; Megachilidae (Megachilini): Megachile inimica sayi sn, Megachile latimanus sn, Megachile mendica sn cp
Halictidae (Doufoureinae): Dufourea marginatus marginatus cp olg (MH, Kr); Halictidae (Halictinae): Agapostemon texanus texanus (MH), Agapostemon virescens sn fq, Augochlorella striata sn, Augochloropsis metallica metallica (MH), Halictus confusus sn, Halictus ligatus sn cp fq, Halictus rubicunda (MH), Lasioglossum imitatus cp, Lasioglossum pilosus pilosus cp, Lasioglossum versatus cp; Halictidae (Nomiinae): Nomia heteropoda (MH), Nomia triangulifera (MH, Kr), Nomia heteropoda kirbii (MH); Andrenidae (Andreninae): Andrena accepta sn cp olg (Rb, Kr), Andrena helianthi sn cp olg (Rb, Kr); Andrenidae (Panurginae): Heterosarus helianthi (Kr), Pseudopanurgus rugosus cp olg (Kr)
Syrphidae: Eristalis brousii sn, Eristalis transversus sn, Syritta pipiens fp np; Bombyliidae: Sparnopolius confusus sn fq, Villa alternata fp np
Nymphalidae: Danaus plexippus (Rb, H), Speyeria cybele; Pieridae: Pieris rapae
Hesperiidae: Polites themistocles
Cantharidae: Chauliognathus pennsylvanicus sn; Chrysomelidae: Acalymma vittata fp np, Diabrotica undecimpunctata fp np; Cleridae: Phyllobaenus pubescens (Mwd)
Miridae: Lygus lineolaris
Albugo tragopogonis parasitises Helianthus annuus
In Great Britain and/or Ireland:
Foodplant / saprobe
gregarious, immersed, then exposed, black pycnidium of Diplodina coelomycetous anamorph of Diplodina helianthi is saprobic on dead stem of Helianthus annuus
Remarks: season: 1-4
Foodplant / parasite
Golovinomyces cichoracearum var. latisporus parasitises Helianthus annuus
Foodplant / feeds on
larva of Terellia serratulae feeds on Helianthus annuus
Other: unusual host/prey
Based on studies in:
USA: California, Cabrillo Point (Grassland)
This list may not be complete but is based on published studies.
- L. D. Harris and L. Paur, A quantitative food web analysis of a shortgrass community, Technical Report No. 154, Grassland Biome. U.S. International Biological Program (1972), from p. 17.
Molecular Biology and Genetics
Barcode data: Helianthus annuus
Statistics of barcoding coverage: Helianthus annuus
Public Records: 8
Specimens with Barcodes: 11
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values.
- Aeschimann, D. & C. Heitz. 2005. Synonymie-Index der Schweizer Flora und der angrenzenden Gebiete (SISF). 2te Auflage. Documenta Floristicae Helvetiae N° 2. Genève. http://www.crsf.ch/
Cultivars, improved and selected materials (and area of origin)
Cultivars: Apache Brown Striped, Autumn Beauty Hybrids, Aztec Gold, Bellezza d’Autuno, Big Smile, Black Oil, Color Fashion Hybrids, Confection, Daisetsuzan, Discovery, Evening Sun, Floristan, Full Sun, Fun Sun, Gloriosa Polyheaded, Gold & Silver, Gray-Stripe, Hallo, Happy Face, Havasupai Striped, Henry Wilde, Holiday, Hopi Dye, Inca Jewels, Incredible, Italian White, Lion’s Mane, Lemon Queen, Luna, Mammoth Russian, Monster, Moonwalker, Music Box, Orange Sun, Park’s Velvet Tapestry, Paul Bunyan, Peredovik, Piccolo, Provance Hybrids, Silverleaf, Sonja, Sun Hybrids, Sunbeam, Sunbright, Sunburst Hybrids, Sunrise, Sunset, Sunspot, Taiyo, Tangina, Teddy Bear, Tarahumara White, Valentine, Vanilla Ice, Velvet Queen, and Zebulon.
HEAN3 is widely available through local nurseries and seed companies.
In pre-European settlement times, the Hidatsa cultivated sunflowers in the following ways (Wilson 1917):
1) Garden plots were created from wooded and brushy areas in river bottomlands.
2) Brush cleared for planting was spread over the plots and burned, for it was conventional wisdom that burning trees and brush “softened the soil and left it loose and mellow for planting”. Burning also added nutrients to the soil.
Before setting fire to the fields, the dry grass, leaves, and brush were removed from the edges of the fields so the fire wouldn’t spread.
3) Plots were allowed to lay fallow, and were taken out of production for two years to let them rejuvenate.
4) Sunflowers were the first seeds planted in the spring. Planting was done using a hoe. Three seeds were planted in a hill, at the depth of the second joint of a woman’s finger. The three seeds were planted together, pressed into the loose soil by a single motion, with the thumb and first two fingers. The hill was heaped up and patted firm. Sunflowers were planted only around the edges of a field. The hills were placed eight or nine paces apart.
There were several varieties of sunflowers; black, white, red, and striped colors occurred in the seeds.
5) Seeds were harvested by spreading sunflower heads on the roof to dry. The heads were laid face downward, with the backs to the sun. After the heads had dried for four days, the heads were threshed by laying them on the floor face downwards and beating them as a stick. An average threshing filled a good-sized basket, with enough seed left over to make a small package.
6) Parched sunflower seeds were pounded in the corn mortar to make meal. Sunflower meal was used in a dish called four-vegetables-mixed; it included beans, dried squash, pounded parched sunflower seed, and pounded parched corn.
7) Sunflower seed balls were made of sunflower seed meal. In the olden times, every warrior carried a bag of soft skin with a sunflower-seed ball, wrapped in a piece of buffalo-heart skin. When worn with fatigue or overcome with sleep and weariness, the warrior took out his sunflower-seed ball, and nibbled at it to refresh himself.
Each garden plot was “owned” and tended by a woman who cleared it. It was kept cleared of weeds and birds were chased off.
Relevance to Humans and Ecosystems
The Cherokee used an infusion of sunflower leaves to treat kidneys.
The Dakota used an infusion of sunflowers for chest pains and pulmonary troubles.
The Gros Ventres, Rees, and Mandan used sunflowers ceremonially; oil from the seeds were used to lubricate or paint the face and body.
The Gros Ventres, Mandan, Rees, and Hidatsa used sunflower seeds as a stimulant, taken on a war party or hunt to alleviate fatigue.
The Hopi used the sunflower plant as a “spider medicine” and dermatological aid.
The Navajo ate sunflower seeds to stimulate the appetite.
The Navaho-Kayenta used the plant for the sun sand painting ceremony and as a disinfectant to prevent prenatal infections caused by the solar eclipse.
The Navaho-Ramah used a salve of pulverized seed and root to prevent injury from a horse falling on a person and as a moxa of the pith to remove warts.
The Paiute used a decoction of sunflower root to alleviate rheumatism.
Pawnee women ate a dry seed concoction to protect suckling children.
The Pima applied a poultice of warm ashes to the stomach for worms and used a decoction of leaves for high fevers and as a wash for horses’ sores caused by screwworms.
The Thompson Indians used powdered sunflower leaves alone or in an ointment on sores and swellings.
The Zuni used a poultice of sunflower root to treat snakebite, along with much ritual and ceremony.
Ethnobotanic: The sunflower is a native domesticated crop. During the last 3,000 years, Indians increased the seed size approximately 1,000 percent. They gradually changed the genetic composition of the plant by repeatedly selecting the largest seeds (Yarnell 1978).
Originally cultivated by North American Indians, it has a long and interesting history as a food plant (Kindscher 1987). Sunflower seeds were and still are eaten raw, roasted, cooked, dried, and ground, and used as a source of oil. Flower buds were boiled. The roasted seeds have been used as a coffee substitute. The Mescalero and Chiricahua Apache made extensive use of wild sunflowers. The Hidatsa used wild verse cultivated sunflowers in the production of cooking oil because the seeds of their smaller flower heads produced superior oil (Wilson 1917). In the Northeast, sunflowers are part of the Onandaga (Iroquois) creation myth (Gilmore 1977). In the Southwest, the Hopi believe that when the sunflowers are numerous, it is a sign that there will be an abundant harvest (Whiting 1939). In the prairies, the Teton Dakota had a saying, “when the sunflowers were tall and in full bloom, the buffaloes were fat and the meat good” (Gilmore 1977).
Helianthus seeds were eaten by many California natives, and often ground up and mixed with other seeds in pinole (Strike 1994). The sunflower was used for food in Mexico and had reputed medicinal value in soothing chest pains (Heiser 1976). Francisco Hernandez, an early Spanish explorer, ascribed aphrodisiac powers to the sunflower (Ibid.).
Charles H. Lange, an anthropologist at the University of Texas, wrote that “among the Cochiti, a reliable ‘home remedy’ for cuts and other wounds is the juice of freshly crushed sunflower stems. The juice is smeared liberally over the wounds, bandaged, and invariably results in a speedy recovery, with never a case of infection” (Heiser 1976).
According to Moerman (1986) sunflowers were used in the following ways:
Purple and black dyes extracted from wild sunflowers were used to dye basketry materials. A yellow dye was also derived from the ray flowers. The Hopi Indians grew a sunflower variety with deep purple achenes, and obtained a purple dye by soaking them in water (Heiser 1976). The dye was used to color basketry or to decorate their bodies.
The Teton Dakotas boiled flower heads from which the involucral bracts had been removed as a remedy for pulmonary troubles (Gilmore 1977). Pawnee women who became pregnant while still nursing a child took a sunflower seed medicine to prevent sickness in the child (Kindscher 1992). In the southwest, Zuni medicine men cured rattlesnake bites by chewing the fresh or dried root, then sucking the snakebite wound (Camazine and Bye 1980).
The wild sunflower was worn in the hair of the Hopi Indians of Arizona during various ceremonies, and carved wooden sunflower disks found at a prehistoric site in Arizona almost certainly were employed in ceremonial rituals (Heiser 1976).
Agricultural: Early American colonists did not cultivate sunflowers. The sunflower probably went from Mexico to Spain, and from there to other parts of Europe (Heiser 1976). The Russians developed the Mammoth Russian or Russian Giant sunflower and offered these varieties as seeds, which in 1893 were reintroduced to the United States. Sunflowers are used as a source of vegetable oil. The seeds are used for snacks and for bird food.
Medicinal: Medicinal uses for the sunflower utilized by the Europeans include use as a remedy for pulmonary affections, a preparation of the seeds has been widely used for cold and coughs, in the Caucasus the seeds have served as a substitute for quinine in the treatment of malaria, and sunflower seeds are used as a diuretic and expectorant (Heiser 1976). Sunflower pith has been used by the Portuguese in making moxa, which was used in the cauterization of wounds and infections. An infusion from the flowers has been used to kill flies.
A variety of terpenoid compounds have been found in Helianthus species, primarily sesquiterpene lactones and diterpenes (Gershenzon and Mabry 1984). These substances probably offer sunflowers protection against some insects.
Horticultural: Sunflowers are cultivated as ornamentals or garden plants, where the blooms are cherished for their beauty, and the seeds can be eaten by both humans and wildlife. Game birds, songbirds, and rodents (Martin et al. 1951) eat the large, nutritious seeds of sunflowers. These attractive weedy plants are of outstanding value to wildlife in the prairies and other parts of the West. Birds eating the seeds include Wilson snipes, doves, grouse, ring-necked pheasants, quail, blackbirds, bobolinks, lazuli buntings, black-capped chickadees, cowbirds, white-winged crossbills, crows, house finches, goldfinches, purple grackles, horned larks, longspurs, meadowlarks, white-breasted nuthatches, pyrrhuloxias, ravens, sparrows, and tufted titmice. Small mammals who relish the seeds include the least chipmunk, eastern pocket gopher, ground squirrels, lemmings, meadow mice, pocket mice, white-footed mice, prairie dogs, and kangaroo rats. Muskrats eat the stems and foliage. Antelope, deer, and moose browse on the plants.
Industry: Sunflower stalks have been used as fuel, fodder for livestock, food for poultry, and ensilage (Heiser 1976). In the Soviet Union, after the dried flower stalks have been used for fuel, the ashes are returned to the soil. The seed hulls could be used for “litter” for poultry or returned to the soil or composted. A few years ago, it was found that the hulls could be used in fuels. Today the hulls are used in the Soviet Union in manufacturing ethyl alcohol and furfural, in lining plywood, and in growing yeast. The stems have been used as a source of commercial fiber. The Chinese have used this fiber for the manufacturing of fabrics. Other countries are experimenting with the use of fiber in paper.
Helianthus annuus, the common sunflower, is an annual species of sunflower grown as a crop for its edible oil and edible fruits (sunflower seeds). Sunflower is also used as bird food, as livestock forage (as a meal or a silage plant) and in some industrial applications. The plant was first domesticated in the Americas. Wild Helianthus annuus is a widely branched annual plant with many flower heads. The domestic sunflower, however, possesses a single large inflorescence (flower head) atop an unbranched stem. The name sunflower may derive from the flower's head's shape, which resembles the sun, or from the false impression that the blooming plant appears to slowly turn its flower towards the sun as the latter moves across the sky on a daily basis.
The plant has an erect rough-hairy stem, reaching typical heights of 3 meters. The tallest sunflower on record achieved 8.23 m (27 ft). Sunflower leaves are broad, coarsely toothed, rough and mostly alternate. What is often called the "flower" of the sunflower is actually a "flower head" (or flower heads) of numerous small individual 5=petaled flowers (florets). The outer flowers, which resemble petals, are called ray flowers. Each "petal" consists of a ligule composed of fused petals of an asymmmetrical ray flower. They are sterile and can be yellow, red, orange, or other colors. The flowers in the center of the head are called disk flowers. These mature into fruits (sunflower "seeds"). The disk flowers are arranged spirally. Generally, each floret is oriented toward the next by approximately the golden angle, 137.5°, producing a pattern of interconnecting spirals, where the number of left spirals and the number of right spirals are successive Fibonacci numbers. Typically, there are 34 spirals in one direction and 55 in the other; on a very large sunflower there could be 89 in one direction and 144 in the other. This pattern produces the most efficient packing of seeds within the flower head.
Most cultivars of sunflower are variants of Helianthus annuus, but four other species (all perennials) are also domesticated. This includes H. tuberosus, the Jerusalem Artichoke, which produces edible tubers.
Mathematical model of floret arrangement
where θ is the angle, r is the radius or distance from the center, and n is the index number of the floret and c is a constant scaling factor. It is a form of Fermat's spiral. The angle 137.5° is related to the golden ratio (55/144 of a circular angle, where 55 and 144 are Fibonacci numbers) and gives a close packing of florets. This model has been used to produce computer graphics representations of sunflowers.
The sunflower, Helianthus annuus, genome is diploid with a base chromosome number of 17 and an estimated genome size of 2871–3189 Mbp. Some sources claim its true size is around 3.5 billion base pairs (slightly larger than the human genome).
Cultivation and uses
To grow best, sunflowers need full sun. They grow best in fertile, moist, well-drained soil with heavy mulch. In commercial planting, seeds are planted 45 cm (1.5 ft.) apart and 2.5 cm (1 in) deep. Sunflower "whole seed" (fruit) are sold as a snack food, raw or after roasting in ovens, with or without salt and/or seasonings added. Sunflowers can be processed into a peanut butter alternative, sunflower butter. In Germany, it is mixed with rye flour to make Sonnenblumenkernbrot (literally: sunflower whole seed bread), which is quite popular in German-speaking Europe. It is also sold as food for birds and can be used directly in cooking and salads. American Indians had multiple uses for sunflowers in the past, such as in bread, medical ointments, dyes and body paints.
Sunflower oil, extracted from the seeds, is used for cooking, as a carrier oil and to produce margarine and biodiesel, as it is cheaper than olive oil. A range of sunflower varieties exist with differing fatty acid compositions; some 'high oleic' types contain a higher level of monounsaturated fats in their oil than even olive oil.
The cake remaining after the seeds have been processed for oil is used as a livestock feed. Some recently developed cultivars have drooping heads. These cultivars are less attractive to gardeners growing the flowers as ornamental plants, but appeal to farmers, because they reduce bird damage and losses from some plant diseases. Sunflowers also produce latex, and are the subject of experiments to improve their suitability as an alternative crop for producing nonallergenic rubber.
Traditionally, several Native American groups planted sunflowers on the north edges of their gardens as a "fourth sister" to the better known three sisters combination of corn, beans, and squash. Annual species are often planted for their allelopathic properties.
However, for commercial farmers growing commodity crops, the sunflower, like any other unwanted plant, is often considered a weed. Especially in the Midwestern US, wild (perennial) species are often found in corn and soybean fields and can have a negative impact on yields.
Sunflowers can be used in phytoremediation to extract toxic ingredients from soil, such as lead, arsenic and uranium, and used in rhizofiltration to neutralize radionuclides and other toxic ingredients and harmful bacteria from water. They were used to remove caesium-137 and strontium-90 from a nearby pond after the Chernobyl disaster, and a similar campaign was mounted in response to the Fukushima Daiichi nuclear disaster.
A common misconception is that flowering sunflower heads track the Sun across the sky. Although immature flower buds exhibit this behaviour, the mature flowering heads point in a fixed (and typically easterly) direction throughout the day. This old misconception was disputed in 1597 by the English botanist John Gerard, who grew sunflowers in his famous herbal garden: "[some] have reported it to turn with the Sun, the which I could never observe, although I have endeavored to find out the truth of it." The uniform alignment of sunflower heads in a field might give some people the false impression that the flowers are tracking the sun.
The uniform alignment results from heliotropism in an earlier development stage, the bud stage, before the appearance of flower heads (anthesis). The buds are heliotropic until the end of the bud stage, and finally face East. Their heliotropic motion is a circadian rhythm, synchronized by the sun, which continues if the sun disappears on cloudy days. If a sunflower plant in the bud stage is rotated 180°, the bud will be turning away from the sun for a few days, as resynchronization by the sun takes time. The heliotropic motion of the bud is performed by the pulvinus, a flexible segment just below the bud, due to reversible changes in turgor pressure, which occurs without growth.
Although it was commonly accepted that the sunflower was first domesticated in what is now the Southeastern US, roughly 5000 years ago, there is evidence that it was first domesticated in Mexico around 2600 BC. These crops were found in Tabasco, Mexico at the San Andre's dig site. The earliest known examples in the United States of a fully domesticated sunflower have been found in Tennessee, and date to around 2300 BC. Many indigenous American peoples used the sunflower as the symbol of their solar deity, including the Aztecs and the Otomi of Mexico and the Incas in South America. In 1510 early Spanish explorers encountered the sunflower in the Americas and carried its seeds back to Europe. Of the four plants known to have been domesticated in what is now the eastern continental United States  and to have become important agricultural commodities, the sunflower is currently the most economically important.
During the 18th century, the use of sunflower oil became very popular in Russia, particularly with members of the Russian Orthodox Church, because sunflower oil was one of the few oils that was allowed during Lent, according to some fasting traditions.
Among the Zuni people, the fresh or dried root is chewed by the medicine man before sucking venom from a snakebite and applying a poultice to the wound. This compound poultice of the root is applied with much ceremony to rattlesnake bites. Blossoms are also used ceremonially for anthropic worship.
- The sunflower is the state flower of the US state of Kansas, and one of the city flowers of Kitakyūshū, Japan.
- The sunflower is often used as a symbol of green ideology. The sunflower is also the symbol of the Vegan Society.
- During the late 19th century, the flower was used as the symbol of the Aesthetic Movement.
- Subject of Van Gogh's series of paintings, Sunflowers
- The sunflower is the national flower of Ukraine.
- The sunflower was chosen as the symbol of the Spiritualist Church for many reasons, but mostly because it turns toward the sun as "Spiritualism turns toward the light of truth". As stated earlier in the article, this is in fact, not true. Modern Spiritualists often have art or jewelry with sunflower designs.
- Starting from February 2010, Kuban Airlines of Russia painted part of its fleet in a new livery featuring enormous sunflowers.
- Sunflowers were also worshipped by the Incas because they viewed it as a symbol for the Sun.
- The sunflower is the symbol behind the Sunflower Movement, a 2014 mass protest in Taiwan.
- American Giant
- Autumn Beauty
- Aztec Sun
- Black Oil
- Chianti Hybrid
- Claret agm
- Dwarf Sunspot
- Evening Sun
- Giant Primrose
- Gullick's Variety agm
- Indian Blanket Hybrid
- Irish Eyes
- Italian White
- Kong Hybrid
- Large Grey Stripe
- Lemon Queen agm
- Loddon Gold agm
- Mammoth Russian
- Miss Mellish agm
- Mongolian Giant
- Orange Sun
- Pastiche agm
- Peach Passion
- Prado Red
- Red Sun
- Ring of Fire
- Solar Eclipse
- Strawberry Blonde
- Sunny Hybrid
- Teddy Bear
- Thousand Suns
- Valentine agm
- Velvet Queen
- Yellow Disk
There are many species in the sunflower genus Helianthus, and many species in other genera that may be called sunflowers.
- The Maximillian sunflower (Helianthus maximiliani) is one of 38 species of perennial sunflower native to North America. The Land Institute 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 perennial sunflower.
- 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.
- "Tallest Sunflower". Guiness World Records. Retrieved 4 May 2014.
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- Prusinkiewicz, Przemyslaw; Lindenmayer, Aristid (1990). The Algorithmic Beauty of Plants. Springer-Verlag. pp. 101–107. ISBN 978-0-387-97297-8.
- "Helianthus annuus (common sunflower) Genome Project". NCBI. Retrieved 2012-02-20.
- Helianthus annuus at National Center for Biotechnology Information (NCBI)
- "Sunflower Genome Holds the Promise of Sustainable Agriculture". ScienceDaily. 2010-01-14.
- Pelczar, Rita. (1993) The Prodigal Sunflower. American Horticulturist 72(8).
- Kuepper and Dodson (2001) Companion Planting: Basic Concept and Resources
- Nikneshan, P., Karimmojeni, P., Moghanibashi, M., Hosseini, N. (2011) Australian Journal of Crop Science. 5(11):1434-40. ISSN:1835-2707. Allelopathic potential of sunflower on weed management in safflower and wheat
- Adler, Tina (July 20, 1996). "Botanical cleanup crews: using plants to tackle polluted water and soil". Science News. Retrieved 2010-09-03.
- AFP (June 24, 2011). "Sunflowers to clean radioactive soil in Japan". Yahoo News. Retrieved 2011-06-25.
- Antoni Slodkowski; Yuriko Nakao (19 August 2011). "Sunflowers melt Fukushima's nuclear "snow"". Reuters. Retrieved 22 January 2012.
- "Many people are under the misconception that the flower heads of the cultivated sunflower (Helianthus annuus) track the sun... Immature flower buds of the sunflower do exhibit solar tracking and on sunny days the buds will track the sun across the sky from east to west... However, as the flower bud matures and blossoms, the stem stiffens and the flower becomes fixed facing the eastward direction." Hangarter, Roger P. "Solar tracking: sunflower plants". Plants-In-Motion website. Indiana University. Retrieved 22 August 2012.
- "Sunflowers in the blooming stage are not heliotropic anymore. The stem has frozen, typically in an eastward orientation.".
- Gerard, John (1597). Herball, or Generall Historie of Plantes. London: John Norton. pp. 612–614. Retrieved 2012-08-08. Popular botany book in 17th century England
- "Sunflower, Developmental stages (life cycle)". GeoChemBio website. Retrieved 8 August 2012.
- ""Diurnal E-W oscillations of the heads occurred initially but ceased as the flowers opened and anthesis commenced, leaving the heads facing east." Lang, A.R.G.and J. E. Begg (1969). Movements of Helianthus annuus Leaves and Heads. Journal of Applied Ecology 16:299-305".
- "When the plant is in the bud stage, it tends to track the movement of the sun across the horizon. Once the flower opens into the radiance of yellow petals, it faces east." National Sunflower Association
- Donat-Peter Häder; Michael Lebert (2001). Photomovement. Elsevier. pp. 673–. ISBN 978-0-444-50706-8. Retrieved 15 August 2010.
- Blackman et al. (2011). . PNAS.
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