Vascular Plants of North Carolina
Account for Toothed Rosinweed - Silphium dentatum   Elliott
Members of Asteraceae:
Members of Silphium with account distribution info or public map:
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Section 6 » Family Asteraceae
AuthorElliott
DistributionMostly Piedmont, scattered in a few montane counties.

NC to TN, south to FL and AL.
AbundanceUncommon in most of the range in the Piedmont, and rare in the Mountains.
HabitatDry to mesic woodlands and forest openings, clearings, clearcuts, roadside banks, fields, pastures
PhenologyFlowering and fruiting late June-September.
IdentificationPlants grow mostly 3-5 feet tall, with lance-shaped to ovate leaves and a rather small inflorescence of nearly erect branches terminating in yellow heads. Basal leaves are absent at flowering time. The involucral bracts (surrounding each head) are broad, rounded, and thick-textured; thus they differ strongly from bracts of sunflowers (Helianthus).S. asteriscus and S. dentatum have rough surfaces to leaves (vs. smooth in S. asteriscus var. latifolium). Variety asteriscus has tiny hairs on the pales (tiny bracts at the base of each disk floret), but these lack glands (vs. glandular-hairy in S. dentatum).
Taxonomic CommentsMost NC specimens were annotated by J.A. Clevinger in 1999, who studied this species complex. Weakley (2020) pulled this taxon back out of the S. asteriscus complex. Note that in most of the 20th Century, this taxon -- S. dentatum -- had been considered as a good species.

Other Common Name(s)None?
State RankS3
Global RankGNR
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BA SorriePiedmont of Moore, area of Iredell Soil E of Carbonton Road MoorePhoto_natural
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