Flower heads Stephen M. Young

Flower heads
Stephen M. Young

Dicotyledoneae (Dicots)
Asteraceae (Aster Family)
State Protection
Federal Protection
Not Listed
State Conservation Status Rank
Global Conservation Status Rank


Did you know?

Even though the species name is aromatica, the leaves and flowers do not have much of a fragrance. The genus name comes from the Greek word "Agera" which means not growing old and refers to the long-lasting flowers and leaves (Tenaglia 2007).

State Ranking Justification

There are four existing occurrences but two of them have not been found again after one survey. There are 29 historical occurrences beginning in 1868 on Staten Island. Almost all of the historical collections occur between 1868 and 1929 with none later than 1936. Plants were rediscovered in 1991.

Short-term Trends

Short term trends are unknown. Two of the four existing occurrences could not be found a second time but they may still be present.

Long-term Trends

There has been a large decline in populations from historical times. There were many occurrences in the late 1800s and early 1900s but today only a small number of populations can be found.

Conservation and Management


All of the occurrences occur in areas with a lot of human activity and natural succession that might affect the plants.

Conservation Strategies and Management Practices

This species grows in early successional habitats and management strategies should include methods to prevent natural succession from eliminating plants while preventing direct impacts from human activity such as improper road and trail maintenance.

Research Needs

Research is needed to assess the best way to manage for protection of this species.



More information is needed on the habitat preferences of Small White Snakeroot in New York. It has been found growing on mowed roadsides, old railroad corridors that are now trails, and in dry woods (New York Natural Heritage Program 2012). Sandy soils, burned pinelands, turkey oak sand ridges, pine-oak and oak-hickory upland woods, old fields, roadsides, fencerows, moist sites (FNA 2006). Dry woods, especially in sandy soil (Gleason and Cronquist 2001).

Associated Ecological Communities

  • Coastal oak-heath forest* (guide)
  • Coastal oak-hickory forest (guide)
  • Maritime pitch pine dune woodland* (guide)
  • Maritime post oak forest* (guide)
  • Pine barrens shrub swamp* (guide)
  • Pitch pine-scrub oak barrens* (guide)


New York State Distribution

This species is currently known only from Suffolk County on eastern Long island, but it was historically known west to New York City and Staten Island with a report from Westchester County.

Global Distribution

Ageratina aromatica var. aromatica occurs from eastern Massachusetts and southeastern New York south to Florida and west to a line from Ohio to Louisiana.

Best Places to See

  • Long Pond Greenbelt Preserve (Suffolk County)

Identification Comments

General Description

Small White Snakeroot was previously included in the genus Eupatorium. It is an erect perennial herb from about 12 to 28 inches tall. It has opposite, triangular leaves on short petioles, with crenate (wavy) to dentate (toothed) margins. The flower heads occur in clusters of 5 to 10, and have discoid flowers with white corollas about 0.2 inches long. The stems and petioles are covered with fine hairs.

Best Life Stage for Proper Identification

Small White Snakeroot is best identified in flower.

Similar Species

Ageratina altissima (the most similar species) is taller (up to 60 inches), its flowering heads have more flowers (10 to 34), and has longer petioles (up to 1/3 the length of the leaf blade) than Ageratina aromatica var. aromatica. A. altissima also has shorter corollas (about 1/8 to 3/16 of an inch) than those of A. aromatica var. aromatica (3/16 to 1/4 of an inch). Variety aromatica is the only variety of A. ageratina found in New York. Variety incisa is found in Virginia and Florida.

Best Time to See

Surveys for small white snakeroot should be conducted in August or September.

  • Flowering
  • Fruiting

The time of year you would expect to find Small White Snakeroot flowering and fruiting in New York.

Small White Snakeroot Images


Small White Snakeroot
Ageratina aromatica var. aromatica None

  • Kingdom Plantae
    • Phylum Anthophyta
      • Class Dicotyledoneae (Dicots)
        • Order Asterales
          • Family Asteraceae (Aster Family)


  • Eupatorium aromaticum L.

Comments on the Classification

All of our Ageratina aromatica are variety aromatica.

Additional Resources

Best Identification Reference

Flora of North America Editorial Committee. 2006. Flora of North America North of Mexico. Vol. 21. Magnoliophyta: Asteridae, Part 8: Asteraceae, part 3. Oxford Univ. Press, New York. xxii + 616 pp.

Other References

Craine, S. I. 2003. Ageratina aromatica (L.) Spach (Lesser Snakeroot) Conservation and Research Plan for New England. New England Wild Flower Society, Framingham, Massachusetts, USA.

Fernald, M. L. 1950. Gray's manual of botany. 8th edition. Corrected printing (1970). D. Van Nostrand Company, New York. 1632 pp.

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.

Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.

Mitchell, Richard S. 1986. A checklist of New York State plants. Bulletin No. 458. New York State Museum. 272 pp.

Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.

New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.

Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York


About This Guide

This guide was authored by: Stephen M. Young

Information for this guide was last updated on: September 6, 2012

Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Ageratina aromatica var. aromatica. Available from: https://guides.nynhp.org/small-white-snakeroot/. Accessed March 25, 2019.

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