Ageratum conyzoides (tropical whiteweed)

Plate 1 figs. a–h · 8 separate observations

Ageratum conyzoides, photographed by Kevin Faccenda — fig. a Kevin Faccenda, CC BY 4.0 / 2022-05-29 / obs. 203954083

Ageratum conyzoides, photographed by Tyler Bishop — fig. b Tyler Bishop, CC BY 4.0 / obs. 199495439

Ageratum conyzoides, photographed by Josiah Londerée — fig. f Josiah Londerée, CC BY 4.0 / obs. 197947969

Ageratum conyzoides, photographed by Dan Schofield — fig. g Dan Schofield, CC BY 4.0 / obs. 186748434

Ageratum conyzoides, photographed by Jacy Chen — fig. h Jacy Chen, CC BY 4.0 / obs. 184156859

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.

Native range 6 botanical countries

Native distribution of Ageratum conyzoides, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows.

Region	TDWG code	Continent
Mexico Central	MXC	NORTHERN AMERICA
Mexico Gulf	MXG
Mexico Northeast	MXE
Mexico Northwest	MXN
Mexico Southwest	MXS
Ecuador	ECU	SOUTHERN AMERICA

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Flowering 744 in flower of 769 examined

95%

97%

100%

97%

99%

98%

96%

91%

100%

97%

95%

96%

Proportion of examined Ageratum conyzoides in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	69	73	95%	87% to 98%
Feb	60	62	97%	89% to 99%
Mar	56	56	100%	94% to 100%
Apr	98	101	97%	92% to 99%
May	82	83	99%	93% to 100%
Jun	59	60	98%	91% to 100%
Jul	47	49	96%	86% to 99%
Aug	49	54	91%	80% to 96%
Sep	59	59	100%	94% to 100%
Oct	63	65	97%	89% to 99%
Nov	57	60	95%	86% to 98%
Dec	45	47	96%	86% to 99%

Peak flowering in Mar. Each bar is the share of Ageratum conyzoides observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 744 of 769 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Also published as 43 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.

Ageratum album Hort.Berol. ex Hornem.
Ageratum album Steud.
Ageratum arsenei B.L.Rob.
Ageratum brachystephanum Regel
Ageratum ciliare Lour.
Ageratum ciliare L.
Ageratum coeruleum Desf.
Ageratum conyzoides f. album (Willd.) B.L.Rob.
Ageratum conyzoides f. conyzoides
Ageratum conyzoides f. obtusifolia (Lam.) Miq.
Ageratum conyzoides subsp. conyzoides
Ageratum conyzoides subsp. latifolium (Cav.) M.F.Johnson
Ageratum conyzoides var. conyzoides
Ageratum conyzoides var. hirtum (Lam.) DC.
Ageratum conyzoides var. inaequipaleaceum Hieron.
Ageratum conyzoides var. obtusifolium (Lam.) DC.
Ageratum conyzoides var. pilosum Blume
Ageratum cordifolium Roxb.
Ageratum hirsutum Poir.
Ageratum hirsutum Lam.
Ageratum hirsutum Poiret
Ageratum hirtum Lam.
Ageratum humile Larrañaga
Ageratum humile Salisb.

and 19 more.

Sourcesevery claim on this page

World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

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