Who does n’t smile when they see a orbit of sunflowers ? Or finger happy when they put a few sunflower in a vase ? Most of us render the familiar large - channelize , folksy giant when we hear the word “ helianthus . ” This article will search the unlike types ofHelianthussunflowers , including aboriginal perennials and annual , and the many cultivar of the aboriginal one-year sunflower . The Mexican yearly helianthus in the genusTithoniawill also be discussed .
HISTORY
The yearly sunflower ( Helianthus annuus ) is one of the few harvest species that uprise in North America . It was probably a “ camp follower ” of several of the westerly native American tribe who domesticated the harvest as a reference of food . Native Americans selected a grandiloquent , single - head smorgasbord for tameness before European explorers reached North America in the 16th Century . The first Europeans keep sunflowers cultivated in many places from southerly Canada to Mexico .
The helianthus was probably first introduced to Europe through Spain and spread through Europe as an ornamental and medicinal peculiarity until it make Russia where the harvest ’s potential for oil production was shew . According to data from 2016,Europe , Russia , and the Ukraine produce almost 70 % of the world ’s sunflower .
PLANT DESCRIPTION
Native primarily to North and South America , Helianthusis a genus comprising72 species(14 yearly and 39 perennial)of inflorescence plant , plus 19 subspeciesin the class Asteraceae .
The taxonomy gets very complicated ; answer it to say that thegenus Helianthusis disunite into four surgical incision , admit an annual section thatincludes both the educate native sunflower ( unwashed sunflower)and thewild sunflower ( sometimes referred to as “ cultivate wild relative ” or CWRs , an important informant of genetic diversity used for cover in commercial crop product ) . Most of the popular helianthus cultivar are hybrids ofH. annuus .
WildHelianthus annuusis awidely separate , annual plant with many flower heads . The branching sunflower grows 3 - 9 ’ marvelous , has small flowerheads and small seed , and produce oodles of efflorescence over a peak bloom geological period of 3 - 4 week . The yellow-bellied bloom are 2 - 5 ” broad with dark center . They look very much like fateful - eyed Susan ( Rudbeckia ) , only the blooms are larger , and the plant life are taller .
The domestic annual helianthus — the one grown for food — possesses only a unmarried large inflorescence ( flower brain ) atop an unbranched stem . The single - prow domesticated sunflower grows 5 - 10 ’ ; has coarse , hirsute , ovate to triangular go forth up to 12 ” long ; and a prominent seed head with yellow rays and a colored plaza disc . Flower heads are 3 - 6 ” across .
Both the single - radical and forking - stem native sunflower are identified in the lit asHelianthus annuus L.and are advert to as “ rough-cut helianthus . ”H. annuus L.is know to be an fast-growing spreaderand is also considered a weed in many agricultural areas .
Sunflower heads are made up of taboo ray efflorescence and inner phonograph recording florets . The enceinte petals around the border of a helianthus straits are individual electron beam flowers which can not reproduce on their own and do not develop into seed . The disc florets have both manlike and female sexuality organ and can ego - pollinate . The disk efflorescence give path to sunflower seeds .
USES
Sunflower seeds are typically used to make edible fossil oil , hoot ejaculate , stock feed , and food for snacking . Two canonical type of sunflowers are typically grown : oil germ sunflowersandconfection sunflowers . Oil source sunflowers are in the first place grown for producing sunflower oil and birdie seed . helianthus oil colour has been research as a potential diesel engine fuel backup man , since sunflower oil has an vigour content equivalent to 93 pct of telephone number 2 U.S. Rudolf Diesel fuel .
Confection sunflowers bring forth big come on big heads and have opprobrious stripes along the seed coat . This type is primarily spring up for human wasting disease . Growing sunflowers for ornamental role , such as cut bloom in flowered arrangements , is a fairly late trend that has become more popular since the intro of pollenless sunflowers .
HELIOTROPISM
sunflower have motor cells in the flower psyche , whichmove the head so that it faces the sun ( Heliotropism).A sunflower “ faces ” or follow the sun east to west through the sky and returns at night to confront the Orient , ready for the morning Lord’s Day . researcher say the immature plant ’s sun - trailing can be explain by circadian rhythms – the behavioral changes which follow a 24 - hour cycle that is connect to an inner clock . The plant ’s turning is a result of dissimilar sides of the stem elongating at different times of day . study have shown thatthis movement leads to increased vegetal biomass and enhanced pollinator visit . Heliotropism only occur during early stages before the efflorescence take shape germ . As the flower buds maturate and prime , the stem stiffens , and the blossom becomes fixed face the eastward direction .
ALLELOPATHY
Allelopathyis a biological phenomenon whereone plant inhibits the growing of another through the release of allelochemicals . This protective system reduces challenger from plant nearby . Research that I found is focalize on the effect of sunflowers on agricultural crop . Sunflowers give off toxins from their source , rot leaf , and stem leachates . Field studies have shown that the soil around sunflowers are rich in chemicals , with greatest concentrations under the aerial canopy of the plant , and decreasing with length away from the flora . In the undermentioned season , harvest in these fields did badly not because of lack of nutrient , but because of sunflower residues and stay chemical substance . The efficaciousness of sunflower toxin is such that thesunflower extracts are being considered as potential constitutional weed killer . Potatoes are very sensitive to sunflower toxin , butnot all flora are pretend . Although I find some lists of plants that are considered resistant to the toxic effects , I did n’t find supporting studies . The photo ofH. Anuus‘Mammoth Russian ’ shows that Russian salvia ( Salvia yangii , antecedently known asPerovskia atriplicifolia ) is apparently not sham by sunflower toxin . Its elevation did forbid the sunflowers from getting enough sunshine in the former increment stage , and so I would not plant sunflower in this spot next season . I ’ll be interested to see if the Russian sage , a perennial , read negative effects next year .
GROWING helianthus
Sunflowers are easy to develop , and seeded player can be sown at once outdoors into the ground or in containers , once the peril of icing has fall out and the soil has warm up to above 50 ° degree Fahrenheit . If you ’ve had a job with squirrels or bird deplete the seeds , plant can be start indoors in kitty for transfer outside . When plants issue , lean every other seed , allow 12 - 15 ” between plant . row should have a minimum of 2 - 3 ’ of space between them . Sunflowers do best when develop in well - draining , more or less acidic soil with a pH from 6.0 - 6.8 in location that get 6 - 8 hours of direct sun . Sunflowers , especially the multi - floral , branching type or single , prominent - flowered cultivar , can be heavy soil feeders . Work organic matter into the bottom before planting , and then hold a slow - release fertilizer as a side dressing a couple of times during the time of year . Irrigate shortly after the diligence of fertiliser to allow for it to move into the root zone of the plant . irrigate them regularly 20 day before and after bloom to promote root growing , which helps anchor taller sunflowers contain top - heavy blooms . Once established , sunflower can withstand some drouth . helianthus broadly speaking grow well with 1 inch of water per week , whether from rain or supplemental irrigation . It is of import to control weeds to forestall competition with the sunflowers for nutrition and wet . As they mature , tumid sunflower may need funding to deal with strong winds or top oppressiveness from seed production .
EXTEND THE BLOOM
you could have helianthus bloom all time of year foresightful throughsuccession planting . There are three ways of doing this :
Anotherinteresting recommendationcomes from Master Gardeners Olson , Liskey , and Habeck at the Oregon State University Extension Service who designed and manage for a sunflower demonstration garden . They imbed 18 variety of helianthus arrange by height from 15”-12 ’ . They found that the shortest sunflowers flower earliest . establish on their demonstration results , they recommendplanting the marvellous mixture first , mid - sized assortment three to four weeks later , and the short helianthus about two week after that .
PESTS AND INSECTS
Deer can demolish young , developing plants apace . If cervid have access code to your helianthus , repellents or fence may be necessary . ( See this article,“Deer , Deer , Deer!”fromThe Garden Shed . ) Stink bugs , leafage - footed bugs , Nipponese beetle , and aphids can be a trouble . Be mindful thatsunflowers also pull an enormous bit of beneficial insects and pollinators . employ extreme caution if consider an insecticide . According to the Native Plant Finder by Zip Code,66 aboriginal butterflies and moths habituate sunflower as caterpillar innkeeper . See the top 15 cat place at thisLINK . sunflower may also demonstrate periodic fungous infections such as rusts and mildews . Powdery mold and downy mold are on occasion institute on the leaves of sunflower , typically involve the sure-enough leaves first . If the works are old enough and have vigor , they can normally spring up despite these disease .
SPECIES Native to the Charlottesville / Albemarle County Area
The Native Plant Finder by Zip Codeshows9 perennial helianthus native to our domain . See the board below for a summary of requirement by sunlight and soil . A abbreviated description for each of these mintage is include after the summary tabular array so that you could understand more about the sunflowers best suit to your landscape painting .
FULL SUN
PARTIAL SUN
FULL SUN TO SHADE
PERENNIAL SPECIES Native to the Charlottesville / Albemarle County Area
H.mollis – Ashy Sunflower , Hairy Sunflower , Downy Sunflower
This sunflower typically grows 2 - 4 ’ grandiloquent . Conspicuously pubescent ( covered with short , soft tomentum ) , gray - green leaves and halt , picture a grayish ash tree - alike color , thus giving rise to the plebeian name of ash-grey sunflower . Flowers build up singly from the upper stems , with each flower having a 4 ” diameter . Flowers bloom from July - September . flora in full sun . ash-gray sunflower generally suffer a wide variety ofwell - drained territory , including modal , arenaceous , and poor jumpy ground . Avoid clay soils . Plants distribute by rhizome into broad clumpsthat are often difficult to properly maintain in a conventional molding . It is not described as cervid resistant .
H.giganteus – Giant Sunflower
This wildflower mature 3 - 9′ tall , with a forficate , purplish root word that carry concluding , yellow flowers that blossom July - September . Despite this industrial plant ’s name , its flower top dog are comparatively small , 2 - 3″ across ; the vulgar and species names refer to the flora ’s overall height . The root organisation has fleshy fibrous roots and shallow rhizomes . Small colonies of plantsoften develop from the rhizomes . It prefersfull sun , slopped - to - moist condition , and sandy soil . Because giant sunflower hap in wetlands , its large stalk are sometimes used by beavers in the grammatical construction of their dams and lodges . The root and leaves can cause skin discomfort in world . The plant can be fateful to animals if ingested .
H. Maximilinia – Maximilian Sunflower , Max Sunflower
This helianthus has several tall , leafy , branched staunch that grow to 3 - 10 ’ tall . Leaves vary in distance from 10 ” near the bottom of the stem to 2 ” near the top . Flowers are 5 ” across with chickenhearted shaft and dark yellow - to - brown center of attention . Bloom meter is August - September . Although itprefers full sunlight in moist cadaver - like soil , it can bear a across-the-board range of soils . This sunflower is eaten by many stock but is reportedlyNOT attractive to deer . A heavy harvest of seeds makes it worthful for wildlife . This is a very big , vigorous agriculturist that can form large colony . It spreads via vegetational sprouting from a thick rhizome , and from semen . It should not be planted in the middle of flush beds as it eventually overtakes its neighbor .
H. strumosus – Paleleaf Sunflower , Paleleaf Woodland Sunflower , Woodland Sunflower
The stalwart , erect , mostly smooth stem of paleleaf woodland helianthus is branched toward the top and grow to 7 ’ tall . minute , oval leaves are up to 8 ” foresightful and whitish underneath , throw the common name of paleleaf . Flower capitulum , 2 - 4 ” across with yellow rays and a yellow heart , grow in informal bunch at limb tips from July - September . The plant grow in full sunshine to part - shade to shadow and likes dry , well - debilitate acidic soils . It is found in dry , open upland wood and Mrs. Henry Wood edge . It spread by rhizomes and colonize quickly . This plant life is reportedlydeer and rabbit resistant .
H. atrorubens – Purpledisc Sunflower , Appalachian Sunflower
This 3 - 4 ’ tall plant is found inrocky , clay , or sandy soilsof woodland and along route banks infull sun to partial shade . Daisy - like flowers are 2 ” wide with chicken rays fence in a dark regal - brown magnetic disk . Several flower blush on item-by-item 3″ pedicels ( stem that confiscate a undivided peak to the blossoming ) . It excels in open woodland gardens , cottage gardens , and sundry perennial beds . It has shallow rhizome and isnot described as an aggressive spreader . It bloom from July until the first hoar . This is a larval legion plant that supports Silvery Checkerspot butterfly stroke ( Chlosyne nycteis ) . It isdeer and drought resistant .
H.grosserratus – Sawtooth Sunflower
Notwithstanding its name , the sawtooth sunflower has leave of absence that are toothless or only slightly serrated . This plant is 3 - 12′ tall , with considerable mutation in the size of it of plants across different fix . Plants that grow in dull colony are only 3 - 5′ tall , but “ alone wolf ” industrial plant can accomplish considerable meridian . Sawtooth helianthus has politic ruddy stem , with very little branching , except for some inflorescence stem that occur along the upper half of the plant . Each flowerhead is 2½-4″ across . The industrial plant thrives in both brainsick and high - quality sites . It prefersfull Sunday , moist dirt , and fertile loamy soil with gamy organic content . However , this racy plant life will tolerate other sort of soil . Its roots are sinewy and rhizomatous , sometimesforming large coloniesthat exclude other plants . Sawtooth sunflower is reported to be bothdeer and rabbit tolerant .
H. Laevigatus – Smooth Sunflower
This sunflower grows to 7 ’ tall and is abundant in Virginia . It produces umbel ( curt flush stalks which scatter from a usual point ) of brilliant , greenish - xanthous stellate ( star - shaped ) flower from August - November . Smooth sunflower requireshigh light availability . In Virginia , West Virginia , and Maryland , its home ground include gladesand shale barrens , woodland delimitation , teetotal roadsides , and powerline corridors . It is threatened in the first place by flack crushing and by invasion of alien industrial plant coinage , such as spotted knapweed and Japanese honeysuckle . Other threats let in development , excavation for limestone , weed killer use , cut down during the growing and flowering seasons , and road grammatical construction . It spreadsby means of undercover rhizomes . It is not described as deer repellent .
H.decapetalus – Thin - folio Sunflower , Ten - Petal Sunflower , Narrow - leaved Sunflower
This wildflower is about 3 - 5′ tall ; it is erect and arm now and again . The folio blades are up to 7″ long and 3″ across ; foliage margins are sharply serrated ; and the tips of its leafage sword are unusually long and sylphlike . Each flowerhead is about 2–3½ ” across , with bright yellow rays and tubular yellow disk florets . The bloom stop is July - October . It prefer partial sun or dappled sunlight , moist to mesic condition , and a robust loamy soil . This speciesmay go around aggressivelyin some position . It is attractive to deer . It is a larval master of ceremonies plant to many moths and butterfly , including the silverish checkerspot butterfly ( Chlosyne nycteis ) , and paint lady butterfly ( Vanessa cardui ) .
H. divaricatus – Woodland Sunflower , Rough Sunflower
This plant is easily grown inaverage , dry - to - medium , well - drained soil in part shade . It is found in rough or flaxen woodlands and in dry open web site and is tolerant of a wide chain of mountains of grunge conditions . peak are 2″ across with bright yellow rays , and slenderly - darker - white-livered center disc . The efflorescence menstruation is July - September . Smooth stem produce 2 - 6 ’ tall with short - stalk 6 ” leaf . This helianthus is well - suit to a native / pollinator garden , naturalized field , or forest garden , and is a good snub flower . Woodland helianthus isrhizomatous and forms coloniesover time . Divide every 3 - 4 long time to hold in spread and maintain vigor . It is reportedly cervid and rabbit insubordinate .
PERENNIAL SUNFLOWER cultivar
There are also cultivars of perennial sunflower . TheChicago Botanic Garden Plant Finderis a proficient reference for information on bothannual and perennial cultivar . Cultivars of the perennial aboriginal to our area admit : H. maximiliani‘Lemon Yellow’,H. maximiliani‘Dakota Sunshine ’ , andH. divaricatus‘Chartreuse Butterflies ’ .
ANNUAL helianthus CULTIVARS
One of the most placeable garden flower is the classicannual sunflowerHelianthus annuus . It has been hybridized into many varieties , including those with red-faced , orangish , and bicolored petals , nanus and mammoth varieties , and those with three-fold heyday head . The University of Minnesota Extensiondescribesannual cultivarsaccording to 5 family : branching , pollenless , nanus , semi - dwarf , andgiant . It also ply a sample of popular cultivars for each . The following chart provides a summary . ‘ Kong ’ and ‘ Tiger Eye ’ were added as examples .
ANNUAL CULTIVAR CATEGORY summary
Branchingcultivars get quite large and produce an copiousness of blooms over a long period . They require a in effect deal of room , so space them 18 - 24 ” aside .
Pollenlesscultivars are used mainly as burn flowers or garden plants . Pollen - free eccentric do not hold any of the brilliantly yellowish pollen that can stain habiliment or tablecloths . Heights place from 2 - 8 ’ with a variety of flower colors and forms .
Dwarfcultivars are 3 ’ tall or less . They generally work well in front of bottom or border , in limited spaces or in container . * I implant both ‘ Teddy Bear ’ and ‘ Sunspot ’ cultivars this spring from cum . The first problem was that birds ate the set seed . The 2d job was that cervid devoured the plants both before blush and after flower . See phot
Semi - dwarfcultivars are 3 - 8 ’ tall and unremarkably do not require gage . These cultivars broadly speaking solve well in the layer or borders of most home landscape .
Giantcultivars grow to a height of 8 ’ or more . These cultivars sometimes require staking due to the size of it of the plant , flowers , and seed heads . Space plants about 2 ’ apart for good air - circulation .
TIPS FOR HARVESTING SUNFLOWER SEEDS
sunflower are matured when the back of the heads turn icteric and finally brown and ironic . Most of the chickenhearted petal will have dried and fall , with the seeded player still plump . Seed heads can ripen on the plant , but they will need protection from birds . Try covering the heads with a composition carrier bag or cheesecloth once the flower petal start turning brown if you need to protect the seeds . See thisarticlefor info on how to prepare seeds for wasting disease by both shuttle and people .
POLLENLESS helianthus
Pollenless sunflowers originated as a mutation , a hereditary computer error . They are male - unimaginative : the C of individual floweret that compose the inflorescence of pollenless sunflowers produce no pollen . Although theflowers have ambrosia , bees would still need to collect pollen from another source . Pollen is a source of aminic acids for bees and is used to feed untested larva . have extra trips to get pollen and nectar from different flowers is less effective . Other pollinating worm may or may not frequent pollenless helianthus . Most pollinating beetles , for example , are pollen eater and will avoid pollenless helianthus . butterfly and hoverflies , however , feed mostly on nectar and are unfazed by the lack of pollen . If there are epicene sunflowers within pollinate distance of pollenless sunflowers , the pollenless flowers can be pollinated to some extent and acquire seeds . But otherwise , no nutrient for the birds!Pollenless sunflowers make good deletion flowers but are not very beneficial to wildlife .
TITHONIA ROTUNDIFOIA – MEXICAN SUNFLOWER
Mexican helianthus is an annual in the family Asteraceae , but it is in the genusTithonia , rather thanHelianthus . It is aboriginal to Mexico and Central America . The speciesTithoniadiversifoliais list by the University of Florida as beingvery invasive . It disseminate by self - seeding and by stolons . The speciesT. rotundifoliais not encroaching . This mintage will be discussed in this clause .
T. rotundifoliagrows4 - 6 ’ tall ( sometimes up to 10 ! ) , with a great central stalk . The solitary 3 ” flowers have orange to orange - red ray and orange - yellow disks . The flowers , which make courteous cut flowers , areattractive to a wide kind of bees , butterfly , and hummingbird . flower are produce from mid - summer until Robert Lee Frost . The foliage and fore are deal with a gentle downy tomentum , and the underside of the leaves are hairy.T.rotundifoliagrows salutary infull sun in pathetic to average , well - drain grease . Avoid planting in racy territory and avoid heavy fertilizing ; these praxis will advertize excess foliage and weak fore . Cut off the spent heyday to elevate more bloody . Shelter from strong malarkey if possible ; staking is also very helpful . The flowers are followed by grey - to - black flattened triangular seeds that are easy to collect for succeeding planting . Tithoniacan be grown from cum , either imbed forthwith in the garden after the last icing date or , for early blooms , started indoors 6 - 8 weeks before the average last day of the month of hoar . Sow shallowly as light is necessitate for sprouting . Although an yearbook , this flora will generously ego - seed . Because of its marvellous stature and uncouth grain , this sunflower is best used at the back of borders and beds to shape a backdrop for shorter plants . It has few pests or disease problems and isnot favored by deer . learn for slugs and snail . Tithonianeeds fond cheery conditions to arise well so it may not do much betimes in the season . Be patient and you will be repay with blooms and pollinator !
SUMMARY
Although most multitude are familiar with the marvelous , large - lead yearly helianthus , Helianthus annuus , there are many more helianthus diverseness available . There are bothnative recurrent species and numerous cultivar ofH. annuus . They come in unlike size of it , material body , and colour to liven the previous - season garden , although some perennials start blooming as early as July and keep on flower until late fall ! Cultivars rove from a dwarf at 15 ” for the front of the garden , to mammoth varieties that hulk in the back . You should be able-bodied to identify different aboriginal perennial species that check your landscape weather . Both annuals and perennial can easy be grow from seminal fluid , although seeds for the less conversant repeated varieties may be more difficult to find . For the yearly hybrid , remember thatseeds of hybrid will not produce plant that are “ true to sow ” the next season . If you require consistency in plant from year to class , it is best to start with new seed . Perennial miscellanea can also be propagate by division . The yearly varieties are very susceptible to cervid damage , but some recurrent potpourri are report as deer resistant . tally for deer opposition by metal money . Perennial helianthus are rhizomatousand most need elbow room to spread . Some coinage are described as unspoilt addition to repeated borders ; others are described as aggressive coloniser and are recommended for rude country . The Mexican helianthus , Tithonia rotundifolia , is anannual sunflowerthat pull in many pollinatorsand offers abright splatter of orange - Red River in the summertime - fall garden .
SOURCES
aboriginal Plant Finder by Zip Code , https://www.nwf.org / NativePlantFinder / Plants/1561
“ Sunflowers , ” University of Minnesota Extension , https://extension.umn.edu / flowers / sunflowers#giant - cultivars-2103964
“ Utilization of Sunflower Crop Wild Relatives for Cultivated Sunflower Improvement , ” Crop Science , https://acsess.onlinelibrary.wiley.com / doi/10.2135 / cropsci2016.10.0856
“ Helianthus , ” Chicago Botanic Garden Plant Finder , https://www.chicagobotanic.org / plantcollections / plantfinder?plant_search = sunflower
“ Growing Sunflowers in the Home Garden , ” University of Georgia Extension , https://extension.uga.edu / publications / detail.html?number = C1121&title = Growing%20Sunflowers%20in%20the%20Home%20Garden
“ What is Heliotropism , ” West Virginia University Extension Service , https://extension.wvu.edu / lawn - gardening - pest / news/2025-01-18 / what - is - heliotropism
“ Allelopathic Plants . 7 . Sunflowers ( Helanthus annuusL.),”Allelopathy Journal(2003),https://www.researchgate.net / profile / A - Azania / publication/287761119_Allelopathic_Plants_7_Sunflower_Helianthus_annuus_L / links/56e8a0ef08ae9bcb3e1cd8d3 / Allelopathic - Plants-7 - Sunflower - Helianthus - annuus - L.pdf
“ Eliminating the Competition – Allelopathy in works , ” Illinois Extension , https://extension.illinois.edu / blog / natural scientist - news/2021 - 02 - 12 - eliminating - competitionallelopathy - plant life
“ Why All the Buzz About Pollenless Sunflowers?”Laidback Gardener , Welcome to Larry Hodgson ’s World , https://laidbackgardener.blog/2025-05-18 / why - all - the - buzz - about - pollenless - sunflowers/
“ Giant Sunflower , Helianthus giganteus , ” Illinois Wildflowers , https://www.illinoiswildflowers.info / wetland / plants / gnt_sunflower.html
“ Helianthus atrorubens,”NC State Extension , https://plants.ces.ncsu.edu / plants / helianthus - atrorubens/
“ Helianthus divaricatus , ” Missouri Botanical Garden Plant Finder , http://www.missouribotanicalgarden.org / PlantFinder / PlantFinderDetails.aspx?kempercode = k390
“ Helianthus divaricatus , Rough Sunflower , Woodland Sunflower , ” NC State Extension , https://plants.ces.ncsu.edu / industrial plant / sunflower - divaricatus/
“ Sawtooth Sunflower , Helianthus grosseserratus , “ Illinois Wildflowers , https://www.illinoiswildflowers.info / prairie / plantx / swt_sunflowerx.htm
“ Helianthus mollis,”Missouri Botanical Garden Plant Finder , http://www.missouribotanicalgarden.org / PlantFinder / PlantFinderDetails.aspx?taxonid=277330
“ Helianthus laevigatus , ” NatureServe Explorer , https://explorer.natureserve.org / Taxon / ELEMENT_GLOBAL.2.140707 / Helianthus_laevigatus
“ Know Your Natives – Woodland Sunflower – Helianthus strumosus , ” Arkansas Native Plant Society , https://anps.org/2025-04-02 / know - your - natives - forest - sunflower/
“ Helianthus decapetalus , ” NC State Extension , https://plants.ces.ncsu.edu / plant / sunflower - decapetalus/
“ Ten - Petal Sunflower , Helianthus decapetalus , ” Illinois Wildflowers , https://www.illinoiswildflowers.info / savannah / plants / tp_sunflower.htm
‘ helianthus bust onto the Scene with New Personalities , ” Oregon State University Extension Service , https://extension.oregonstate.edu / news / sunflowers - burst - scene - newfangled - personality
“ Sunflower Seeds Are for the Birds – and hoi polloi , ” Michigan State University Extension , https://www.canr.msu.edu / news / sunflower_seeds_are_for_the_birds_and_people
“ Mexican Sunflower , Tithonia rotundifolia , ” Wisconsin Horticulture Division of Extension , https://hort.extension.wisc.edu / clause / mexican - sunflower - tithonia - rotundifolia/
“ Tithonia rotundifolia , ” Missouri Botanical Garden Plant Finder , http://www.missouribotanicalgarden.org / PlantFinder / PlantFinderDetails.aspx?kempercode = b763
FEATURE PHOTO : H. annuus‘Kong ’ with bee . picture : Melissa queen
