Ageratina altissima(L.) R.M.King & H.Rob.

white snakeroot

WFO wfo-0000080123 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h

Ageratina altissima, photographed by Ira Gershenhorn
fig. a Ira Gershenhorn, CC0 1.0 / 2022-06-05 / obs. 204003620
Ageratina altissima, photographed by KB DiAngelo
fig. b KB DiAngelo, CC BY-SA 4.0 / obs. 205738715
Ageratina altissima, photographed by Nash Turley
fig. c Nash Turley, CC BY 4.0 / obs. 200795362
Ageratina altissima, photographed by Zakqary Roy
fig. d Zakqary Roy, CC BY 4.0 / obs. 200068463
Ageratina altissima, photographed by Cecil Smith
fig. e Cecil Smith, CC BY 4.0 / obs. 170231960
Ageratina altissima, photographed by Bill Keim
fig. f Bill Keim, CC BY 4.0 / obs. 197992889
Ageratina altissima, photographed by Eric Baratta
fig. g Eric Baratta, CC BY 4.0 / obs. 168902878
Ageratina altissima, photographed by Ira Gershenhorn
fig. h Ira Gershenhorn, CC0 1.0 / obs. 167803167

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

Flowering n = 10,151 observations

Peak flowering in Sep, from 10,151 community-annotated observations worldwide. This is a global aggregate, not a forecast for your garden: the same species flowers on different dates in different hemispheres, and citizen-science records cluster near cities, at weekends, and in spring. Where a species has fewer than 30 annotated records we do not draw this chart at all.

Also published as 35 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Ageratina ageratoides Spach
  • Ageratina altissima var. angustata (A.Gray) Clewell & Wooten
  • Ageratum altissimum L.
  • Batschia nivea Moench
  • Eupatorium aboriginum Greene
  • Eupatorium ageratoides var. angustatum A.Gray
  • Eupatorium altissimum (L.) L.
  • Eupatorium boreale Greene
  • Eupatorium cordatum var. fraseri (Poir.) DC.
  • Eupatorium eurybiaefolium Greene
  • Eupatorium frasieri Poir.
  • Eupatorium frasieri Poiret
  • Eupatorium odoratum Walter
  • Eupatorium roanense Small
  • Eupatorium rugosum Houtt.
  • Eupatorium rugosum f. rugosum
  • Eupatorium rugosum f. villicaule (Fernald) Fernald
  • Eupatorium rugosum var. angustatum (A.Gray) S.F.Blake
  • Eupatorium rugosum var. chlorolepis Fernald
  • Eupatorium rugosum var. roanense (Small) Fernald
  • Eupatorium rugosum var. rugosum
  • Eupatorium rugosum var. tomentellum (B.L.Rob.) S.F.Blake
  • Eupatorium rugosum var. villicaule (Fernald) S.F.Blake
  • Eupatorium urticifolium Reichard

and 11 more.

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.

We publish what we can source and we say so when we cannot. This page has no care advice, no toxicity claim and no native range, because we do not yet have those from a source we can cite.