Decodon verticillatus (swamp loosestrife)

Plate 1 figs. a–h

Decodon verticillatus, photographed by Lynn Harper — fig. a Lynn Harper, CC0 1.0 / 2021-12-29 / obs. 174044046

Decodon verticillatus, photographed by Zac Peterson — fig. b Zac Peterson, CC BY 4.0 / obs. 193424413

Decodon verticillatus, photographed by Marilynn Miller — fig. c Marilynn Miller, CC BY 4.0 / obs. 164514040

Decodon verticillatus, photographed by Eric Knight — fig. e Eric Knight, CC BY 4.0 / obs. 170115602

Decodon verticillatus, photographed by Jacob Friend — fig. f Jacob Friend, CC0 1.0 / obs. 154650647

Decodon verticillatus, photographed by Steven Lamonde — fig. g Steven Lamonde, CC BY 4.0 / obs. 155643014

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 = 610 observations

122

403

Flowering observations of Decodon verticillatus by month
Month	Observations
Jan	0
Feb	0
Mar	1
Apr	0
May	0
Jun	3
Jul	122
Aug	403
Sep	78
Oct	3
Nov	0
Dec	0

Peak flowering in Aug, from 610 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 6 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.

Decodon aquaticus J.F.Gmel.
Decodon verticillatus var. laevigatus Torr. & A.Gray
Decodon verticillatus var. pubescens Torr. & A.Gray
Decodon verticillatus var. verticillatus
Lythrum verticillatum L.
Nesaea verticillata Kunth

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.

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.