Ageratina adenophora(Spreng.) R.M.King & H.Rob.

Crofton Weed

WFO wfo-0000022875 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h

Ageratina adenophora, photographed by Greg Tasney
fig. a Greg Tasney, CC BY-SA 4.0 / 2022-06-05 / obs. 203442846

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 = 1,300 observations

Flowering observations of Ageratina adenophora by month
MonthObservations
Jan22
Feb68
Mar269
Apr308
May209
Jun101
Jul39
Aug24
Sep59
Oct124
Nov49
Dec28

Peak flowering in Apr, from 1,300 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 4 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.

  • Eupatorium adenophorum Spreng.
  • Eupatorium adenophorum var. adenophorum
  • Eupatorium adenophorum var. peruvianum Hieron.
  • Eupatorium pasadenense Parish

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.