''Helianthus debilis'' is a species of

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

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 Vascular Plants''. Institute for Systematic Botany, University of South Florida, Tampa. It is native to the United States, where it can be found along the

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

and Gulf Coasts.''Helianthus debilis''.
Flora of North America. It is known elsewhere as an

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...

, such as

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the no ...

Slovakia Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the ...

, and

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

. This species may be an annual or perennial herb. It is usually perennial but it may last only one season in climates where freezes occur.Gilman, E. F. and S. Park-Brown
''Helianthus debilis'' Beach Sunflower.
Environmental Horticulture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. 1999. Revised 2007. It can reach a height of 2 meters. The stem grows from a

taproot A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproo ...

and may grow erect or decumbent. It can also spread along the ground, becoming a dense groundcover. The leaves are usually arranged alternately and are variable in shape and size. The largest are up to 14 centimeters long by 13 wide. The showy

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

is a single

flower head A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

or an array of two or three heads. There are up to 30 lance-shaped

phyllaries In botanical terminology, a phyllary, also known an involucral bract or tegule, is a single bract of the involucre of a composite flower. The involucre is the grouping of bracts together. Phyllaries are reduced leaf-like structures that form one o ...

each up to 1.7 centimeters long. There are up to 20 or 21Christman, S
''Helianthus debilis''.
Floridata.com. 1999. Updated 2003. ray florets, each up to 2.3 centimeters long. They are usually yellow in the wild, but

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

s have been bred to bear whitish, reddish, or orange florets. The center of the head is filled with many red, yellowish, or purplish disc florets. The fruit, a cypsela, is roughly 2 or 3 millimeters long. There are several subspecies. At one point there were eight.Wain, R. P. (1983)
Genetic differentiation during speciation in the ''Helianthus debilis'' complex.
''Evolution'' 37(6) 1119-27. Five are currently recognized.The Plant List, ''Helianthus debilis'' Nutt.
/ref> * ''Helianthus debilis'' subsp. ''cucumerifolius'' - cucumberleaf sunflower. The subspecies with the widest distribution.''Helianthus debilis'' ssp. ''cucumerifolius''.
Flora of North America. *''Helianthus debilis'' subsp. ''debilis'' - beach 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 are indigenous to a place are not endemic to it if they are also found else ...

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

.''Helianthus debilis'' ssp. ''debilis''.
Flora of North America. *''Helianthus debilis'' subsp. ''silvestris'' - forest sunflower. Endemic to

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

.''Helianthus debilis'' ssp. ''silvestris''.
Flora of North America. *''Helianthus debilis'' subsp. ''tardiflorus'' - slow-flowering sunflower.

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

to Florida.''Helianthus debilis'' ssp. ''tardiflorus''.
Flora of North America. Limited to rare, specialized coastal habitat.''Helianthus debilis'' ssp. ''tardiflorus''.
NatureServe. *''Helianthus debilis'' subsp. ''vestitus'' - clothed sunflower, hairy beach sunflower.''Helianthus debilis'' ssp. ''vestitus''.
NatureServe. Endemic to Florida.''Helianthus debilis'' ssp. ''vestitus''.
Flora of North America. Imperiled; known from about 22 occurrences. This species grows in several types of coastal habitat, sometimes directly on the beach. It tolerates a moderately saline environment, but not an excessive amount of salt spray or inundation.Gann, G. D., et al. 2005-2013
East Coast dune sunflower ''Helianthus debilis''.
Natives For Your Neighborhood. The Institute for Regional Conservation. Delray Beach, Florida, USA. It is highly

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

-tolerant and it will grow in low-nutrient and poor soils, such as alkaline and acidic soils and sand. The plant attracts butterflies and birds feed on the fruits. This plant is used as a garden flower. It is also good for landscaping, especially in poor, dry soils. It is planted on beaches, where it forms a sand-binding groundcover that prevents

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

and stabilizes dunes.Maura, C. and S. Sanders
''Helianthus debilis'' ssp. ''debilis'' Plant Fact Sheet.
USDA NRCS Brooksville Plant Materials Center. 2002. It requires supplemental watering only rarely, if ever. It may get "ratty-looking" after the showy flowers have withered. Available cultivars include 'Italian White', 'Flora Sun','Dazzler', 'Excelsior', and 'Orion'.

Gallery

Dune Sunflowers growing in Miami Beach sand dunes (South Beach) File:Miami Beach - Sand Dunes Flora - Sea Grapes and Dune Sunflowers 01.jpg, Sea Grapes and Dune Sunflowers File:Miami Beach - Sand Dunes Flora - Dune Sunflower.jpg, Dune Sunflower Closeup

References

{{Taxonbar, from=Q12212016 debilis Flora of the United States Plants described in 1841