Polygonella robusta (largeflower jointweed)

Plate 1 figs. a–h · 8 separate observations

Polygonella robusta, photographed by Stan Shebs — fig. a Stan Shebs, CC BY-SA 4.0 / 2021-10-10 / obs. 170062016

Polygonella robusta, photographed by Athena Philips — fig. b Athena Philips, CC BY 4.0 / obs. 135194827

Polygonella robusta, photographed by Valerie Anderson — fig. c Valerie Anderson, CC BY 4.0 / obs. 102393187

Polygonella robusta, photographed by Daniel Estabrooks — fig. d Daniel Estabrooks, CC0 1.0 / obs. 98914330

Polygonella robusta, photographed by natalie — fig. e natalie, CC0 1.0 / obs. 111631181

Polygonella robusta, photographed by Claire Herzog — fig. g Claire Herzog, CC BY 4.0 / obs. 204896630

Polygonella robusta, photographed by Brandon Corder — fig. h Brandon Corder, CC BY 4.0 / obs. 201108868

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 108 in flower of 122 examined

88%

71%

38%

83%

92%

89%

100%

96%

Proportion of examined Polygonella robusta in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	7	8	88%	53% to 98%
Feb	4	4	too few examined
Mar	5	7	71%	36% to 92%
Apr	3	3	too few examined
May	3	8	38%	14% to 69%
Jun	3	4	too few examined
Jul	5	6	83%	44% to 97%
Aug	12	13	92%	67% to 99%
Sep	17	19	89%	69% to 97%
Oct	17	17	100%	82% to 100%
Nov	10	10	100%	72% to 100%
Dec	22	23	96%	79% to 99%

Peak flowering in Oct. Each bar is the share of Polygonella robusta 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. 108 of 122 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 3 months have fewer than 5 examined observations, so no proportion is drawn for them. 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 2 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.

Polygonella fimbriata var. robusta (Small) Horton
Thysanella robusta Small

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.

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. It has no native range either: Kew's checklist does not cover this taxon.