''Helianthus debilis'' is a species of

sunflower The common sunflower (''Helianthus annuus'') is a species of large annual forb of the daisy family Asteraceae. The common sunflower is harvested for its edible oily seeds, which are often eaten as a snack food. They are also used in the pr ...

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 oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

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 ther ...

, such as

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...

Slovakia Slovakia, officially the Slovak Republic, 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 west, and the Czech Republic to the northwest. Slovakia's m ...

, and

Cuba Cuba, officially the Republic of Cuba, is an island country, comprising the island of Cuba (largest island), Isla de la Juventud, and List of islands of Cuba, 4,195 islands, islets and cays surrounding the main island. It is located where the ...

. 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 taproot ...

and may grow erect or decumbent. It can also spread along the ground, becoming a dense

groundcover Groundcover or ground cover is any plant that grows low over an area of ground, which protects the topsoil from erosion and drought. In a terrestrial ecosystem, the ground cover forms the layer of vegetation below the shrub layer known as the ...

. 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 In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is a single

flower head A pseudanthium (; : pseudanthia) 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, composite flowers ...

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 kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

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 only 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 foun ...

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

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

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

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

Mississippi Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...

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 a period of 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, ...

-tolerant and it will grow in low-nutrient and poor soils, such as

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

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 Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

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