Global Menu

  • Neon Science
  • Data Portal
  • Biorepository
  • NSF NEON | Open Data to Understand our Ecosystems
  • Biorepository Data Portal

  • Search
    • Sample search
    • Map search
    • Dynamic Species List
    • Taxonomic Explorer
  • Images
    • Image Browser
    • Image Search
  • Checklists
    • Research Sites - Invertebrates
    • Research Sites - Plants
    • Research Sites - Vertebrates
  • Sample Use
    • Sample Use Policy
    • Sample Request
    • Data Usage Policy
  • Additional Information
    • Tutorials and Help
    • About NEON
    • NEON Data Portal
    • ASU Biocollections
    • About Symbiota
  • Getting Started
Login New Account Sitemap
Helianthus decapetalus L.  
Family: Asteraceae
thinleaf sunflower
[Helianthus scrophulariifolius Britt., moreHelianthus tracheliifolius Hook.]
Helianthus decapetalus image
Paul Rothrock  
  • FNA
  • Gleason & Cronquist
  • Web Links
Edward E. Schilling in Flora of North America (vol. 21)
Perennials, 60-200 cm (rhizomatous). Stems erect, glabrous. Leaves cauline; opposite (proximal or all) or alternate (distal); petioles (1-)2-5 cm; blades (green, 3-nerved distal to bases) lanceolate to ovate, 7-21 × 4-10 cm, bases rounded to cuneate (often shortly decurrent onto petioles, margins usually serrate (moderately to notably in larger leaves), abaxial faces ± scabro-hispidulous, relatively sparsely gland-dotted. Heads 3-6(-10). Peduncles 2-12 cm (not gland-dotted). Invo-lucres hemispheric, 12-25 mm diam. Phyllaries 20-25 (often reflexed), lance-linear to lanceolate, 11-16 × 2-3 mm (sometimes leaflike, longest surpassing discs by 1/2+ their lengths), (margins ciliate) apices attenuate, abaxial faces strigillose to glabrate, not gland-dotted. Paleae 8-10 mm, 3-toothed. Ray florets 8-12; laminae 20-25 mm. Disc florets 40+; corollas 6.5-7.2 mm, lobes yellow; anthers usually dark brown to black (rarely reddish brown ), appendages dark or reddish brown. Cypselae 3.5-5 mm; pappi of 2 aristate scales 3-4 mm. 2n = 34, 68. Flowering summer-fall. Mesic to wet woodland edges; 10-1200 m; N.B., Ont., Que.; Ala., Ark., Conn., Del., D.C., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis. Helianthus decapetalus is sometimes confused with Heliopsis helianthoides because of shared habitats and superficial similarities. The tetraploid cytotype of H. decapetalus intergrades (and apparently hybridizes) with H. strumosus, particularly in the southern Appalachians; individual specimens can be difficult to place in one or the other species. In addition to morphologic differences, H. decapetalus usually occurs in more mesic habitats, particularly along watercourses; H. strumosus is found in drier sites such as roadside slopes. Helianthus ×multiflorus Linnaeus is a sterile hybrid, often with 'doubled' heads (in which disc florets are replaced by ray florets); it is cultivated and is sometimes included within H. decapetalus, e.g., H. decapetalus var. multiflorus (Linnaeus) A. Gray; its parents are H. decapetalus and H. annuus.

Vascular plants of NE US and adjacent Canada
Perennial from slender rhizomes; stem 0.5-1.5(-2) m, glabrous below the short-hairy infl; lvs thin, pale beneath, moderately scabrous to subglabrous, broadly lanceolate to ovate, 8-20 נ3-8 cm, long-acuminate, serrate (generally sharply so), ±abruptly contracted near the base and decurrent onto the 1.5-6 cm petiole; upper lvs usually alternate; disk yellow, 1-2 cm wide; invol bracts very loose, thin, green, conspicuously ciliate, occasionally hispidulous on the back, attenuate- acuminate, at least some of them usually conspicuously surpassing the disk; rays 8-15, 1.5-3.5 cm; 2n=34, 68. Woods and along streams; Me. and Que. to Wis. and Io., s. to Ga. and Mo. Aug.-Oct. (H. trachelifolius)

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
  • BOLD Systems - Barcode of Life Data Systems
  • Encyclopedia of Life
  • Flora of North America
  • Google Images
  • Google Search Engine
  • International Plant Names Index
  • NCBI - National Center for Biotechnology Information
  • USDA PLANTS Database
  • W3Tropicos
Helianthus decapetalus
Open Interactive Map
Helianthus decapetalus image
Paul Rothrock  
Helianthus decapetalus image
Paul Rothrock  
Helianthus decapetalus image
Click to Display
4 Total Images
NSF NEON | Open Data to Understand our Ecosystems The National Ecological Observatory Network is a major facility fully funded by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.