Overview

Comprehensive Description

Description

Annual (in ours) or perennial herbs. Leaves alternate (in ours). Capitula large, solitary and terminal or laxly corymbose, heterogamous, radiate; ray florets neuter, yellow; disk florets bisexual, fertile. Phyllaries 2-3-seriate. green and herbaceous. Receptacular scales folded, partly enclosing achenes at maturity. Achenes ± flattened, slightly angled. Pappus of 2(-4) deciduous bristles.
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© Mark Hyde, Bart Wursten and Petra Ballings

Source: Flora of Zimbabwe

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Ecology

Habitat

Depth range based on 6 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0.5 - 0.5
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Associations

Foodplant / miner
larva of Liriomyza eupatorii mines leaf of Helianthus
Other: minor host/prey

In Great Britain and/or Ireland:
Foodplant / miner
larva of Liriomyza strigata mines leaf of Helianthus

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Known predators

  • R. D. Bird, Biotic communities of the Aspen Parkland of central Canada, Ecology, 11:356-442, from p. 410 (1930).
  • R. D. Bird, Biotic communities of the Aspen Parkland of central Canada, Ecology, 11:356-442, from p. 383 (1930).
Creative Commons Attribution 3.0 (CC BY 3.0)

© SPIRE project

Source: SPIRE

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Evolution and Systematics

Functional Adaptations

Functional adaptation

Fibonacci sequence optimizes packing: sunflowers
 

The seed heads of sunflowers optimize the packing of seeds by arranging them in spirals of Fibonacci numbers.

   
  "Patterning seeds in spirals of Fibonacci numbers allows for the maximum number of seeds on a seed head, packed uniformly, with no crowding at the center and no 'bald patches' at the edges. In other words, the sunflower has found optimal space utilization for its seed head. The Fibonacci sequence works so well for the sunflower because of one key characteristic—growth. On a sunflower seed head, the individual seeds grow and the center of the seed head continues to add new seeds, pushing those at the periphery outwards. Following the Fibonacci sequence ensures growth on the same terms indefinitely. That is to say, as a seed head grows, seeds will always be packed uniformly, and with maximum compactness." (Courtesy of the Biomimicry Guild)

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"The leaf rosettes of the carnivorous Pinguicula moranensis follow a spiral phyllotaxis approaching a Fibonacci pattern while the stalked flowers arise from extra-axillary sites between  the leavesThe leaves of consecutive  articles of such sympodially constructed rosettes  are arranged along a spiral Fibonacci pattern (with divergence angles  around  137°)Sympodial construction  of flowering shoots and leaf rosettes is also known from Aloe, Gunnera and Philodendron." (Grob et al. 2007:857)
  Learn more about this functional adaptation.
  • Grob V; Pfeifer E; Rutishauser R. 2007. Sympodial construction of Fibonacci-type leaf rosettes in Pinguicula moranensis (Lentibulariaceae). Annals of Botany. 100(4): 857-863.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© The Biomimicry Institute

Source: AskNature

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records: 269
Specimens with Sequences: 291
Specimens with Barcodes: 80
Species: 58
Species With Barcodes: 58
Public Records: 30
Public Species: 13
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© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

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Barcode data

Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

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Wikipedia

Helianthus

For other uses, see Sunflower (disambiguation).

Helianthus L. /ˌhliˈænθəs/[2] (sunflower) is a genus of plants comprising about 52 species[3] in the Asteraceae family, all of which are native to North America. The common name "sunflower" also applies to the popular annual species Helianthus annuus.[4] This and other species, notably Jerusalem artichoke (H. tuberosus), are cultivated in temperate regions as food crops and ornamental plants.[5]

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 large 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.

The domesticated sunflower, Helianthus annuus, is the most familiar species. Perennial sunflower species are not as popular for gardens due to their tendency to spread rapidly and become invasive. Whorled sunflowers, Helianthus verticillatus, were listed as an endangered species in 2014 when the U.S. Fish and Wildlife Service issued a final rule protecting it under the Endangered Species Act. The primary threats are industrial forestry and pine plantations in Alabama, Georgia, and Tennessee. They grow to six feet tall and are primarily found in woodlands, adjacent to creeks and moist, prairie-like areas.[6]

Description[edit]

These are usually tall annuals, growing to a height of 50-390 or more cm.

The rough and hairy stem is branched in the upper part in wild plants but is usually unbranched in domesticated cultivars.

The petiolate leaves are dentate and often sticky. The lower leaves are opposite, ovate or often heart-shaped. The upper leaves are alternate and narrower.

They bear one or several to many wide, terminal capitula (flower heads), with bright yellow ray florets at the outside and yellow or maroon disc florets inside. Several ornamental cultivars have red-colored ray florets; all of them stem from a single original mutant.[7] During growth, sunflowers tilt during the day to face the sun, but stop once they begin blooming.

Helianthus species are used as food plants by the larvae of many Lepidoptera species.

Diversity[edit]

Species include:[8][9]

Helianthus 'Strawberry Blonde'

Formerly placed here[edit]

References[edit]

  1. ^ a b "Genus: Helianthus L.". Germplasm Resources Information Network. United States Department of Agriculture. 2011-01-06. Retrieved 2011-02-22. 
  2. ^ Sunset Western Garden Book. Leisure Arts. 1995. pg. 606–607.
  3. ^ Helianthus. Flora of North America.
  4. ^ Shorter Oxford English Dictionary, 6th ed. United Kingdom: Oxford University Press. 2007. p. 3804. ISBN 0199206872. 
  5. ^ RHS A-Z Encyclopedia of Garden Plants. United Kingdom: Dorling Kindersley. 2008. p. 1136. ISBN 1405332964. 
  6. ^ Remillard, Ashley (August 4, 2014) "U.S. Fish and Wildlife Service Issues Final Rule Protecting Three Flowers" Endangered Species Law and Policy Blog, Nossaman LLP
  7. ^ Heiser, C. B. The Sunflower. University of Oklahoma Press. 1981.
  8. ^ a b "GRIN Species Records of Helianthus". Germplasm Resources Information Network. United States Department of Agriculture. Retrieved 2011-02-22. 
  9. ^ "Helianthus". Integrated Taxonomic Information System. Retrieved 2011-02-22. 
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Source: Wikipedia

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