| Author | L. | |
| Distribution | Mostly the Piedmont, and in the central and southern Mountains; disjunct to the outer Coastal Plain: Craven Co., "roadside, US 70, Dover" in 1966; and Pender Co., "causeway across swamp forest, Northeast Cape Fear River near Rocky Point" in 1950.
VA to MO and OK, south to FL and TX. | |
| Abundance | Frequent to common in the eastern and central Piedmont; infrequent to fairly common in the upper Piedmont and the central and southern Mountains. Very rare if still present in the lower Coastal Plain. | |
| Habitat | Dry to mesic woodland edges and forest openings, powerlines, clearcuts, roadside banks, fields, pastures -- favoring somewhat circumneutral or slightly acidic soil. | |
| Phenology | Flowering and fruiting late June-September. | |
| Identification | The Silphium asteriscus complex consists of 5 varieties, according to FNA, 4 of which occur in NC. Plants grow mostly 3-5 feet tall, with lance-shaped to ovate opposite leaves and a rather small inflorescence of nearly erect branches terminating in large yellow heads. Basal leaves are absent at flowering time. The involucral bracts (at the base of each head) are broad, rounded, and thick-textured; thus they differ strongly from bracts of sunflowers (Helianthus). Variety asteriscus and S. dentatum have rough surfaces to the leaves (vs. smooth in var. latifolium). Variety asteriscus may have tiny hairs on the pales (tiny bracts at the base of each disk floret), but these lack glands (vs. glandular-hairy in S. dentatum). Several other Silphium species are similar, with such opposite to whorled leaves and no basal leaves, but this is the only one with scabrous to rough-hairy stems. This can be a reasonably common "sunflower" of powerline clearings in the Piedmont. | |
| Taxonomic Comments | As mentioned above, there are numerous varieties of the species in the state, though exact details of the ranges of each is somewhat uncertain. Weakley (2020) pulled var. dentatum out as a full species -- S. dentatum.
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| Other Common Name(s) | Roughleaf Rosinweed | |
| State Rank | S4? [S5] | |
| Global Rank | G5 | |
| State Status | | |
| US Status | | |
| USACE-agcp | | |
| USACE-emp | | |
