Helianthus debilis is adventive beyond the Atlantic and Gulf coasts of the United States.
Helianthus debilis is a species of sunflower known by the common names cucumberleaf sunflower, beach sunflower, weak sunflower,[2] and East Coast dune sunflower.[3] It is native to the United States, where it can be found along the Atlantic and Gulf Coasts.[4] It is known elsewhere as an introduced species, such as South Africa, Australia, Taiwan, Slovakia, and Cuba.[5]
This species may be an annual or perennial herb.[4] It is usually perennial but it may last only one season in climates where freezes occur.[6] It can reach a height of 2 meters. The stem grows from a taproot and may grow erect or decumbent.[4] It can also spread along the ground, becoming a dense groundcover.[6] 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 is a single flower head or an array of two or three heads. There are up to 30 lance-shaped phyllaries each up to 1.7 centimeters long. There are up to 20[4] or 21[7] ray florets, each up to 2.3 centimeters long. They are usually yellow in the wild, but cultivars have been bred to bear whitish,[7] reddish, or orange florets.[6] The center of the head is filled with many red, yellowish,[4] or purplish[7] disc florets. The fruit, a cypsela, is roughly 2 or 3 millimeters long.[4]
There are several subspecies. At one point there were eight.[8] Five are currently recognized.[1][4]
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.[20] It is highly drought-tolerant and it will grow in low-nutrient and poor soils, such as alkaline and acidic soils and sand.[6][7] The plant attracts butterflies and birds feed on the fruits.[6]
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 and stabilizes dunes.[21] It requires supplemental watering only rarely, if ever. It may get "ratty-looking" after the showy flowers have withered.[20] Available cultivars include 'Italian White',[7] 'Flora Sun',[21]'Dazzler', 'Excelsior', and 'Orion'.[6]
Dune Sunflowers growing in Miami Beach sand dunes (South Beach)
Sea Grapes and Dune Sunflowers
Dune Sunflower Closeup
Wikimedia Commons has media related to 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. It is native to the United States, where it can be found along the Atlantic and Gulf Coasts. It is known elsewhere as an introduced species, such as South Africa, Australia, Taiwan, Slovakia, and Cuba.
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. It can reach a height of 2 meters. The stem grows from a taproot 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 is a single flower head or an array of two or three heads. There are up to 30 lance-shaped phyllaries each up to 1.7 centimeters long. There are up to 20 or 21 ray florets, each up to 2.3 centimeters long. They are usually yellow in the wild, but cultivars 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. Five are currently recognized.
Helianthus debilis subsp. cucumerifolius - cucumberleaf sunflower. The subspecies with the widest distribution. Helianthus debilis subsp. debilis - beach sunflower. Endemic to Florida. Helianthus debilis subsp. silvestris - forest sunflower. Endemic to Texas. Helianthus debilis subsp. tardiflorus - slow-flowering sunflower. Mississippi to Florida. Limited to rare, specialized coastal habitat. Helianthus debilis subsp. vestitus - clothed sunflower, hairy beach sunflower. Endemic to Florida. 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. It is highly drought-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 and stabilizes dunes. 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'.
Helianthus debilis est une espèce de plantes de la famille des Asteraceae[1]. Elle est originaire des la côte est des États-Unis.
Helianthus debilis est une plante vivace ou annuelle pouvant atteindre 2 mètres de haut.
La tige est érigée ou décombante, se développant à partir d'une racine pivotante. Elle peut également se développer à la manière d'un couvre-sol.
Les feuilles sont généralement alternes, de forme et de taille pouvant varier. Les plus grandes feuillent pouvant mesurer jusqu'à 14 centimètres de long et 13 cm de large.
L'inflorescence est un capitule composé de plusieurs fleurons. Les fleurons ligulés, qui sont en périphérie du capitule, mesurant 2,3 cm de long au maximum, peuvent être au nombre de 20 à 21, sont disposés en un seul rang et sont généralement de couleur jaune. Il peut y avoir soit un capitule unique par tige ou un ensemble de 2 à 3 par tige. Chaque capitule est entourée d'un involucre à bractées. Ces bractées sont vertes, lancéolées, mesurant jusqu'à 1,7 cm de long et il peut y en avoir jusqu'à 30 qui entourent les capitules. Le centre du capitule est composé de fleurons de couleur rouge, jaunâtre ou violacée.
Le fruit est une cypsèle mesurant environ 2 à 3 mm de long.
Helianthus debilis est originaire de la côte Est des États-Unis. Elle est adaptée à des types d'habitat côtier et peut-même pousser directement sur les plages. Il tolère les lieux modérément salins mais pas une quantité excessive de brouillard salin et d'inondation. Il supporte très bien les sécheresses. Il n'a aucune difficulté à se développer dans les sols pauvres en nutriments. Il pousse facilement dans le sable[2], dans les limons ainsi que dans les sols alcalins et acides. Cette espèce est très utile car elle permet d'empêcher l'érosion des dunes de sable. Cette espèce a été introduite[3] et s'est naturalisée dans d'autres pays et sur d'autres continents.
L'UICN a indiqué que cette espèce est classée « Préoccupation mineure », ce qui veut dire qu’Helianthus debilis n'est pas en danger d'extinction.
Cette espèce fournit un fourré pour la protection des petits oiseaux et d'autres animaux.
Helianthus debilis contient actuellement 5 sous-espèces reconnues[4] :
Helianthus debilis est cultivée en tant que plante ornementale dans les jardins. Dès lors, plusieurs cultivars ont été créées à des fins ornementales.
On peut notamment citer les cultivars suivants :
Helianthus debilis est une espèce de plantes de la famille des Asteraceae. Elle est originaire des la côte est des États-Unis.
Helianthus debilis é uma espécie de planta com flor pertencente à família Asteraceae.
A autoridade científica da espécie é Nutt., tendo sido publicada em Transactions of the American Philosophical Society, new series 7: 367. 1841.[1]
Trata-se de uma espécie presente no território português, nomeadamente no Arquipélago dos Açores.
Em termos de naturalidade é possivelmente introduzida na região atrás indicada.
Não se encontra protegida por legislação portuguesa ou da Comunidade Europeia.
Helianthus debilis é uma espécie de planta com flor pertencente à família Asteraceae.
A autoridade científica da espécie é Nutt., tendo sido publicada em Transactions of the American Philosophical Society, new series 7: 367. 1841.
Helianthus debilis là một loài thực vật có hoa trong họ Cúc. Loài này được Nutt. mô tả khoa học đầu tiên năm 1841.[1]
Helianthus debilis là một loài thực vật có hoa trong họ Cúc. Loài này được Nutt. mô tả khoa học đầu tiên năm 1841.
