The
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
Helianthus L.Carl Linnaeus was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature...
comprises 52 species and several subspecies in the
AsteraceaeThe family Asteraceae or Compositae is the second largest family of flowering plants, in terms of number of species....
family, all of which are native to
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...
, with some species (particularly
Helianthus annuus (sunflower) and
Helianthus tuberosus (Jerusalem artichoke) cultivated in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
and other parts of the world as food crops and ornamental plants.
The genus is one of many in the Asteraceae that are known as sunflowers.
The
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
Helianthus L.Carl Linnaeus was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature...
comprises 52 species and several subspecies in the
AsteraceaeThe family Asteraceae or Compositae is the second largest family of flowering plants, in terms of number of species....
family, all of which are native to
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...
, with some species (particularly
Helianthus annuus (sunflower) and
Helianthus tuberosus (Jerusalem artichoke) cultivated in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
and other parts of the world as food crops and ornamental plants.
The genus is one of many in the Asteraceae that are known as sunflowers. It is distinguished technically by the fact that the ray flowers, when present, are sterile, and by the presence on the disk flowers of a pappus that is of two awn-like scales that are cauducous (that is, easily detached and falling at maturity). Some species also have additional shorter scales in the pappus, and there is one species that lacks a pappus entirely. Another technical feature that distinguishes the genus more reliably, but requires a microscope to see, is the presence of a prominent, multicellular appendage at the apex of the style.
There is quite a bit of variability among the perennial species that make up the bulk of the species in the genus. Some have most or all of the leaves in a rosette at the base of the plant and produce a flowering stem that has leaves that are reduced in size. Most of the perennials have disk flowers that are entirely yellow, but a few have disk flowers with reddish lobes. One species,
H. radula, lacks ray flowers altogether.
A key to identify the species and a comprehensive listing of species can be found in the Flora North America treatment .
The domesticated sunflower,
Helianthus annuus, is the most familiar species. These are usually tall
annualAn annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...
s, growing to a height of 50-390 or more cm. The rough and hairy
stemA stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , cones or other stems etc. The internodes act as spaces that distance one node from another...
is branched in the upper part in wild plants but is usually unbranched in domesticated cultivars. The petiolate
leavesIn botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...
are dentate and often sticky. The lower leaves are opposite,
ovateOvate can mean:* Shaped like a two-dimensional section through an egg. This is commonly used in botany, for example to describe leaves. It should be distinguished from ovoid, which means shaped like an egg in three dimensions....
or often heart-shaped. The upper leaves are alternate and narrower. They bear one or several to many wide, terminal
capitulaThe term Capitulum can refer to several things:*In botany, a type of flower head where the bracts are located under the basis, such as a Daisy's*In anatomy, the capitulum of the humerus*The Latin word for a Chapter...
(flower heads), with bright yellow ray florets at the outside and yellow or maroon disc florets inside (several ornamental cultivars have recently become popular that have red-colored ray florets, all of these stem from a single original mutant). These flower heads follow the direction of the
sunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
, going from east to west during the day.
Helianthus species are used as food plants by the
larvaA larva is a young form of animal with indirect development, going through or undergoing metamorphosis ....
e of some
LepidopteraLepidoptera is an order of insects that includes moths and butterflies. It is one of the most speciose orders in the class Insecta, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
species (
see list of Lepidoptera that feed on Helianthus).
Species
- Helianthus agrestis : Southeastern Sunflower
- Helianthus angustifolius : Swamp Sunflower
- Helianthus annuus : Common Sunflower, Girasol (Spanish)
- Helianthus anomalus : Western Sunflower
- Helianthus argophyllus : Silverleaf Sunflower
- Helianthus arizonensis : Arizona Sunflower
- Helianthus atrorubens
- Helianthus bolanderi
Helianthus bolanderi is a species of sunflower known by the common names serpentine sunflower and Bolander's sunflower. It is native to California and Oregon, where it grows mainly in mountainous areas, often in serpentine soils. This wild sunflower is an erect annual reaching heights over a meter...
: Serpentine Sunflower
- Helianthus californicus
Helianthus californicus is a species of sunflower known by the common name California sunflower. It is native to California and Baja California, where it grows in many types of habitat. This wild sunflower is an erect perennial growing from a network of tough, woody roots with small rhizomes...
: California Sunflower
- Helianthus carnosus : Lakeside Sunflower
- Helianthus ciliaris
Helianthus ciliaris is a species of sunflower known by the common names Texas blueweed and yerba parda. It is native to much of the south-central United States and northern Mexico, but it can be found elsewhere in North America where it is an introduced species and often a noxious weed...
: Texas Blueweed
- Helianthus cinereus
- Helianthus couplandii : Prairie Sunflower
- Helianthus cusickii
Helianthus cusickii is a species of sunflower known by the common names Cusick's sunflower and turniproot sunflower. It is native to the western United States from California to Idaho, where it grows in mountain forests and foothills. This wildflower is a perennial growing from a thick, fleshy...
: Cusick's Sunflower
- Helianthus debilis : Cucumberleaf Sunflower
- Helianthus debilis ssp. cucumerifolius : Cucumberleaf Sunflower
- Helianthus debelis ssp. debilis : Beach Sunflower, Dune Sunflower
- Helianthus debilis ssp. silvestris : Cucumberleaf Sunflower
- Helianthus debilis ssp. tardiflorus : Cucumberleaf Sunflower
- Helianthus debilis ssp. vestitus : Cucumberleaf Sunflower
- Helianthus decapetalus : Thinleaf Sunflower
- Helianthus deserticola
- Helianthus divaricatus
Helianthus divaricatus, commonly known as the woodland sunflower, is a perennial herb in the composite family. It is native to eastern North America, from Ontario and Quebec in the north, south to Florida and west to Oklahoma and Iowa. It commonly occurs in dry, relatively open sites...
: Woodland Sunflower
- Helianthus eggertii : Eggert's Sunflower
- Helianthus floridanus : Florida Sunflower
- Helianthus giganteus
Helianthus giganteus , is a species of Helianthus native to the eastern United States and southeastern Canada, from Nova Scotia and Ontario west to Minnesota and south to Mississippi and Georgia....
- Helianthus glaucophyllus : Whiteleaf Sunflower
- Helianthus gracilentus
Helianthus gracilentus is a species of sunflower known by the common name slender sunflower. It is native to central and southern California and Baja California, where it is a member of the dry wildfire-prone chaparral ecosystem. This is a perennial herb growing from a thick taproot to heights...
: Slender Sunflower
- Helianthus grosseserratus
Helianthus grosseserratus, commonly known as sawtooth sunflower or thick-tooth sunflower, is an annual sunflower in the family Asteraceae, with a large flowering head ....
: Sawtooth Sunflower
- Helianthus heterophyllus : Variableleaf Sunflower
- Helianthus hirsutus
- Helianthus laciniatus : Alkali Sunflower
- Helianthus laetiflorus
- Helianthus laevigatus : Smooth Sunflower
- Helianthus longifolius : Longleaf Sunflower
- Helianthus maximiliani
Helianthus maximiliani is a species of sunflower known by the common name Maximilian sunflower.Native to much of the eastern half of North America, it is found in parts of the western half as an introduced species. The plant thrives in a number of ecosystems, particularly across the plains in...
: Maximillian Sunflower
- Helianthus microcephalus
Helianthus microcephalus is a perennial species of Helianthus also known as small woodland sunflower or small-wood sunflower or small-head sunflower...
: Small Woodland Sunflower
- Helianthus mollis
- Helianthus multiflorus
- Helianthus neglectus : Neglected Sunflower
- Helianthus niveus
Helianthus niveus is a species of sunflower known by the common names showy sunflower and snowy sunflower. It is native to northern Mexico and the southwestern United States from California to Texas. This is a taprooted annual or perennial sunflower growing to a maximum height over one meter...
- Helianthus niveus ssp. canescens : Showy Sunflower
- Helianthus niveus ssp. tephrodes : Algodones Sunflower
- Helianthus nuttallii
- Helianthus nuttallii ssp. nuttallii : Nuttall's Sunflower
- Helianthus nuttallii ssp. parishii : Parish's Sunflower
- Helianthus nuttallii ssp. Rydbergii : Rydberg's Sunflower
- Helianthus occidentalis
Helianthus occidentalis is a species of sunflower found in the eastern United States. It differs from other, similar species by its sparse leaves, most of which are basal. This perennial flower reaches heights from two to five feet.-References:*Schilling, E. E. Helianthus in: Flora of North...
: Fewleaf Sunflower
- Helianthus occidentalis ssp. occidentalis : Fewleaf Sunflower
- Helianthus occidentalis ssp. plantagineus : Fewleaf Sunflower
- Helianthus paradoxus
Helianthus paradoxus is a threatened species of sunflower found only in west Texas and New Mexico salt marshes. H. paradoxus is most likely a stable hybrid of H. annuus, the common sunflower, and H. petiolaris, and is more tolerant of salt than either parent species. H...
: Paradox Sunflower
- Helianthus pauciflorus
- Helianthus pauciflorus ssp. pauciflorus : Stiff Sunflower
- Helianthus pauciflorus ssp. subrhomboideus : Stiff Sunflower
- Helianthus petiolaris
- Helianthus petiolaris ssp. fallax : Prairie Sunflower
- Helianthus petiolaris ssp. petiolaris : Prairie Sunflower
- Helianthus porteri : Porter's Sunflower
- Helianthus praecox
- Helianthus praecox ssp. hirtus : Texas Sunflower
- Helianthus praecox ssp. praecox : Texas Sunflower
- Helianthus praecox ssp. runyonii : Runyon's Sunflower
- Helianthus praetermissus : New Mexico Sunflower
- Helianthus pumilus : Little Sunflower
- Helianthus radula : Rayless Sunflower
- Helianthus resinosus : Resindot Sunflower
- Helianthus salicifolius : Willowleaf Sunflower
- Helianthus schweinitzii
Helianthus schweinitzii, known by the common name Schweinitz's sunflower, is a perennial wildflower endemic to the Piedmont physiographic province of North Carolina and South Carolina. It is classified in the Sunflower Family...
: Schweinitz's Sunflower
- Helianthus silphioides : Rosinweed Sunflower
- Helianthus simulans : Muck Sunflower
- Helianthus smithii : Smith's Sunflower
- Helianthus strumosus : Paleleaf Woodland Sunflower
- Helianthus tuberosus : Jerusalem Artichoke, Sunchoke
External links