Helianthus decapetalus

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Helianthus decapetalus
File:Helianthus decapetalus - Thinleaf Sunflower.jpg
Chesapeake & Ohio Canal National Historic Park, Washington
Scientific classification
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H. decapetalus
Binomial name
Helianthus decapetalus
L. 1753 not Darl. 1837[1]

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Helianthus decapetalus, known by the common names thinleaf sunflower[2] and thin-leaved sunflower,[3] is a perennial forb in the sunflower family. It is native to the eastern and central United States and Canada, from New Brunswick west to Iowa, Wisconsin, and Ontario, south as far as Georgia and Louisiana.[4][5] It produces yellow composite flowers in late summer or early fall.

The name decapetalus means "with ten petals," referring to the 8-12 ray florets on the flower heads, resembling petals.

Description

File:Helianthus decapetalus L. Thin-leaved or Wild Sunflower..png
Botanical illustration of Helianthus decapetalus (1913)

The smooth slender stem of Helianthus decapetalus is 60 to 200 centimeters (2 to almost 7 feet) tall and branched near the top. The ovate or lanceolate leaves are borne on 2 to 5 centimeter long petioles and have serrated edges. They are 7 to 21 centimeters long and 4 to 10 centimeters wide. Helianthus decapetalus has 3 to 10 flowerheads. Each flowerhead is composed of 21 to 50 disk florets, and 8 to 12 ray florets, which are 2 to 2.5 centimeters long. The bracts are typically 11 to 16 millimeters long, surpassing the flower disk by at least half their length. The fruit are 3.5 to 5 millimeter long cypselae with a pappus of two scales.[6][7][8]

Distribution and habitat

In Virginia it grows in habitats such as floodplain forests and riverbanks.[9] The presence of this species is dependent on appropriate habitat, and it may be eliminated from an area by development, changes in land use, or competition with invasive species.

Ecology

The flowers attract many kinds of insects, including bees and butterflies, some of which, such as the Painted Lady and the Silvery Checkerspot, use the plant as a larval host. The seeds provide a source of food for birds.[10] Muskrats eat the leaves and stems and use the stems in the construction of their lodges.[8]

References

  1. The International Plant Names Index
  2. Lua error in package.lua at line 80: module 'strict' not found.
  3. Lua error in package.lua at line 80: module 'strict' not found.
  4. Biota of North America Program 2014 county distribution map
  5. Lua error in package.lua at line 80: module 'strict' not found. USDA, NRCS. 2014. The PLANTS Database (http://plants.usda.gov). National Plant Data Team, Greensboro, NC 27401-4901 USA.
  6. Britton, Nathaniel Lord & Brown, Addison (1913). An Illustrated Flora of the Northern United States, Canada and the British Possessions: From Newfoundland to the Parallel of the Southern Boundary of Virginia, and from the Atlantic Ocean Westward to the 102d Meridian, Volume 3., p. 484. Charles Scribner's Sons, New York.
  7. Lua error in package.lua at line 80: module 'strict' not found. 'eFloras (2008). Published on the Internet (http://www.efloras.org). Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  8. 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found. Copyright © 2011-2013 New England Wild Flower Society (http://www.newenglandwild.org)
  9. Lua error in package.lua at line 80: module 'strict' not found. Virginia Botanical Associates. (2014). Digital Atlas of the Virginia Flora (http://www.vaplantatlas.org). c/o Virginia Botanical Associates, Blacksburg.
  10. Lua error in package.lua at line 80: module 'strict' not found. Copyright © 2002-2012 Dr. John Hilty. Illinois Wildflowers (http://www.illinoiswildflowers.info)

External links