Ambrosia chamissonisGreene

silver beachweed

WFO wfo-0000000787 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h

Ambrosia chamissonis, photographed by James H. Thomas
fig. a James H. Thomas, CC BY 4.0 / 2022-06-12 / obs. 205678097
Ambrosia chamissonis, photographed by Millie Basden
fig. b Millie Basden, CC BY 4.0 / obs. 189136376
Ambrosia chamissonis, photographed by Madeleine Claire
fig. c Madeleine Claire, CC BY 4.0 / obs. 190251036
Ambrosia chamissonis, photographed by Ellyne Geurts
fig. d Ellyne Geurts, CC0 1.0 / obs. 195424178
Ambrosia chamissonis, photographed by Drew Meyer
fig. e Drew Meyer, CC0 1.0 / obs. 188694088
Ambrosia chamissonis, photographed by Millie Basden
fig. f Millie Basden, CC BY 4.0 / obs. 187114521
Ambrosia chamissonis, photographed by James C. Davis
fig. g James C. Davis, CC BY-SA 4.0 / obs. 186480298
Ambrosia chamissonis, photographed by James C. Davis
fig. h James C. Davis, CC BY-SA 4.0 / obs. 186487318

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 = 371 observations

Peak flowering in Jul, from 371 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 26 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.

  • Ambrosia bipinnatifida (Nutt.) Greene
  • Ambrosia chamissonis f. bipinnatisecta (Less.) W.W.Payne
  • Ambrosia chamissonis f. chamissonis
  • Ambrosia chamissonis var. bipinnatisecta (Less.) J.T.Howell
  • Ambrosia chamissonis var. chamissonis
  • Ambrosia chamissonis var. cuneifolia (Nutt.) W.W.Payne
  • Franseria bipinnatifida var. bipinnatifida
  • Franseria bipinnatifida var. insularis Reiche
  • Franseria chamissonis Less.
  • Franseria chamissonis f. bipinnatisecta (Less.) Calder & Roy L.Taylor
  • Franseria chamissonis f. chamissonis
  • Franseria chamissonis subsp. bipinnatisecta (Less.) Wiggins & Stockw.
  • Franseria chamissonis subsp. chamissonis
  • Franseria chamissonis subsp. typica Wiggins & Stockw.
  • Franseria chamissonis var. bipinnatisecta Less.
  • Franseria chamissonis var. chamissonis
  • Franseria chamissonis var. cuneifolia (Nutt.) Torr. & A.Gray
  • Franseria cuneifolia Nutt.
  • Franseria lessingii Meyen & Walp.
  • Franseria villosa Rydb.
  • Gaertneria bipinnatifida (Nutt.) Kuntze
  • Gaertneria bipinnatifida var. bipinnatifida
  • Gaertneria bipinnatifida var. dubia (Eastw.) A.Heller
  • Gaertneria chamissonis (Less.) Kuntze

and 2 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.