Polymnia canadensisL.

whiteflower leafcup

WFO wfo-0000137491 Accepted WFO 2026-06 8 photographs CC0 / CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Polymnia canadensis, photographed by Brian Finzel
fig. a Brian Finzel, CC BY-SA 4.0 / 2022-05-08 / obs. 196013369
Polymnia canadensis, photographed by Violet T.
fig. b Violet T., CC BY 4.0 / obs. 200295424
Polymnia canadensis, photographed by Bruce Slater
fig. c Bruce Slater, CC BY 4.0 / obs. 194338105
Polymnia canadensis, photographed by Ryan Sorrells
fig. d Ryan Sorrells, CC BY 4.0 / obs. 191164906
Polymnia canadensis, photographed by Yann Kemper
fig. e Yann Kemper, CC0 1.0 / obs. 187773375
Polymnia canadensis, photographed by John Ambler
fig. f John Ambler, CC0 1.0 / obs. 185295231
Polymnia canadensis, photographed by Brian Finzel
fig. g Brian Finzel, CC BY-SA 4.0 / obs. 183794892
Polymnia canadensis, photographed by Harold Smith
fig. h Harold Smith, CC BY 4.0 / obs. 183015789

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 25 botanical countries

Regions where Polymnia canadensis is native: Alabama, Arkansas, Connecticut, District of Columbia, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Michigan, Minnesota, Missouri, New York, North Carolina, Ohio, Oklahoma, Ontario, Pennsylvania, Tennessee, Vermont, Virginia, West Virginia, Wisconsin AlabamaArkansasConnecticutGeorgiaIllinoisIndianaIowaKansasKentuckyMarylandMichiganMinnesotaMissouriNew YorkNorth CarolinaOhioOklahomaOntarioPennsylvaniaTennesseeVermontVirginiaWest VirginiaWisconsin District of Columbia
Native distribution of Polymnia canadensis, 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. Regions too small to draw at this scale are marked with a dot.
RegionTDWG codeContinent
Alabama ALA NORTHERN AMERICA
Arkansas ARK
Connecticut CNT
District of Columbia WDC
Georgia GEO
Illinois ILL
Indiana INI
Iowa IOW
Kansas KAN
Kentucky KTY
Maryland MRY
Michigan MIC
Minnesota MIN
Missouri MSO
New York NWY
North Carolina NCA
Ohio OHI
Oklahoma OKL
Ontario ONT
Pennsylvania PEN
Tennessee TEN
Vermont VER
Virginia VRG
West Virginia WVA
Wisconsin WIS

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 364 in flower of 646 examined

Peak flowering in Jul. Each bar is the share of Polymnia canadensis 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. 364 of 646 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.

Where it actually grows measured, from 2,000 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -11.5 °C -3.8 °C 0.8 °C
Warmest month, mean daily high 25.9 °C 29.5 °C 31.9 °C
Annual rainfall 884 mm 1,124 mm 1,515 mm
Rainfall in the driest quarter 90 mm 221 mm 304 mm

It is found where winters bring hard frost. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 2,000 research-grade observations of Polymnia canadensis that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

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.

  • Polymnia canadensis f. canadensis
  • Polymnia canadensis f. radiata (A.Gray) Fassett
  • Polymnia canadensis f. radiata (A.Gray) Fassett
  • Polymnia canadensis var. canadensis
  • Polymnia canadensis var. radiata A.Gray
  • Polymnia radiata (A.Gray) Small

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.
  3. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
  4. 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.