| Author | (L.) Spach | |
| Distribution | Essentially throughout the state, but perhaps absent from northern outer Coastal Plain and northern Mountains.
MA to OH, south to northern FL and southeastern LA. | |
| Abundance | Fairly common to common in most of the state, except rare in the northwestern corner, and also rare in the far eastern counties. | |
| Habitat | Dry to mesic, occasionally xeric, pine-oak-hickory woodlands, Longleaf Pine--Wiregrass woodlands and savannas, rocky slopes, outcrops, glades, barrens. It is fire-tolerant. | |
| Phenology | Flowering and fruiting August-October. | |
| Identification | Our species of Ageratina can be told from the closely related genus Eupatorium by the greater number of florets per head [12-34 vs. 14 or fewer (most species only 5)]. In the field the heads are brighter white in Ageratina than in any Eupatorium species, a very useful clue. White Snakeroot (A. altissima) is robust, 2-4 feet tall (vs. 1-2.5 feet tall in Lesser Snakeroot), and has larger leaves that are sharply toothed (vs. bluntly toothed or crenate in Lesser Snakeroot). | |
| Taxonomic Comments | Formerly known as Eupatorium aromaticum.
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| Other Common Name(s) | Small-leaved White Snakeroot -- a terrible name, as White Snakeroot is typically used for A. altissima. | |
| State Rank | S5 | |
| Global Rank | G5 | |
| State Status | | |
| US Status | | |
| USACE-agcp | | |
| USACE-emp | | |
