Vascular Plants of North Carolina
Account for Thinleaf Sunflower - Helianthus decapetalus   L.
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Section 6 » Order Asterales » Family Asteraceae
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AuthorL.
DistributionMountains and Piedmont; absent from the Sandhills and known only from Greene and Pitt counties on the Coastal Plain.

Que. to WI and IA, south to GA and MO.
AbundanceFairly common in the mountains and Piedmont; extremely rare into the central Coastal Plain, but essentially absent from the last province.
HabitatBrownwater river floodplain forests, bottomlands, and wooded streamsides; also upslope in mesic to rich hardwoods. This sunflower has a decided preference for shady and rather rich/moist sites.
PhenologyFlowering and fruiting late July-October.
IdentificationThinleaf Sunflower grows up to 5 and even 6 feet tall and is smooth throughout, except for short pubescence in the inflorescence. Leaves are ovate, stalked, toothed, thin-textured, and lack the rough surface of other sunflowers. Note also the dull yellow disk, unusual among our sunflowers. If in doubt, feel the leaves and note the thin, flexible, and smooth character.
Taxonomic CommentsNone

Other Common Name(s)Forest Sunflower, Ten-petal Sunflower
State RankS4 [S5]
Global RankG5
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