Vascular Plants of North Carolina
Account for Carolina Rosinweed + - Silphium compositum var. compositum   Michaux
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Section 6 » Order Asterales » Family Asteraceae
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AuthorMichaux
DistributionMore-or-less throughout the state, but with some gaps, notably the northeastern Outer Coastal Plain and apparently scattered in the Mountains.

VA to TN, south to FL and AL.
AbundanceUncommon to common.
HabitatDry to xeric soils of Longleaf Pine-Wiregrass communities, savannas, sandhills, oak-hickory woodlands, glades and barrens, rocky slopes, clearings, and roadsides.
PhenologyFlowering and fruiting late May-September.
IdentificationSilphium compositum complex consists of 3 varieties plus S. reniforme, according to Weakley (2018); 2 varieties occur in NC. The growth form of all is very distinctive: a basal rosette of very large (a foot long and 8 inches to a foot wide), stalked, basal leaves that lie on the ground, with a single stem 5-7 feet tall and a widely-branched, open inflorescence of relatively small heads. As in other rosinweeds, the heads are yellow and the involucral bracts are thick-textured and rounded. Var. venosum differs in its broader involucres (1.5-3 cm wide vs. 1-1.5) and longer seeds (8-14 mm vs. 6-9). S. reniforme differs in having unlobed leaves, or with a single lobe on each side.
Taxonomic CommentsSome authors, such as FNA, do not recognize any varieties within S. compositum.

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State RankS5
Global RankG5T5
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