| Author | Nuttall | |
| Distribution | Nearly throughout the state, but scarce in the Mountains and of spotty presence in the upper Piedmont.
MA to IN, south to FL and TX; Neotropics. | |
| Abundance | Common to locally abundant in the Coastal Plain, where it outnumbers Common Horseweed (E. canadensis). Infrequent in the Mountains and western Piedmont, but common in the lower Piedmont; outnumbered in these provinces by that species. | |
| Habitat | Dry to xeric sandy soils of stable maritime dunes, dry maritime grasslands, openings in maritime forests, barrens, glades, fields, roadsides, scrapes, cropfields, waste lots, yards, etc. Favors sandy soil more so than does the very similar Common Horseweed. | |
| Phenology | Flowering and fruiting July-November. | |
| Identification | In many ways Southern Horseweed is a diminutive form of Common Horseweed, and it seldom exceeds 3 feet tall, most often 1-2 feet. A key feature is the purplish tip to each flowerhead bract, lacking in Common Horseweed. Plants are more or less glabrate, much less hairy than Common Horseweed. The inflorescence branches are more spreading than are those in Common Horseweed, which has ascending to nearly erect branches. | |
| Taxonomic Comments | Some authors have lumped this entirely into E. canadensis, while others have treated it as a variety or a subspecies -- such as var. pusillus in RAB (1968). In some texts it is placed in the genus Conyza. Weakley (2018) splits it out as a valid species.
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| Other Common Name(s) | None | |
| State Rank | S5 | |
| Global Rank | G5T5 [G5] | |
| State Status | | |
| US Status | | |
| USACE-agcp | | |
| USACE-emp | | |
