Polemonium villosumRudolph ex Georgi

tall Jacob's-ladder

WFO wfo-0001099825 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Polemonium villosum, photographed by Aleksei Baushev
fig. a Aleksei Baushev, CC BY 4.0 / 2021-09-10 / obs. 158433104

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 23 botanical countries

Regions where Polemonium villosum is native: Buryatiya, Inner Mongolia, Irkutsk, Kamchatka, Khabarovsk, Korea, Krasnoyarsk, Kuril Is., Magadan, Manchuria, Primorye, West Siberia, Yakutiya, Finland, North European Russia, Norway, Sweden, Alaska, Alberta, Aleutian Is., British Columbia, Northwest Territories, Yukon BuryatiyaInner MongoliaIrkutskKamchatkaKhabarovskKrasnoyarskMagadanManchuriaPrimoryeWest SiberiaYakutiyaFinlandNorth European RussiaNorwaySwedenAlaskaAlbertaBritish ColumbiaNorthwest TerritoriesYukon Korea
Native distribution of Polemonium villosum, 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
Buryatiya BRY ASIA-TEMPERATE
Inner Mongolia CHI
Irkutsk IRK
Kamchatka KAM
Khabarovsk KHA
Korea KOR
Krasnoyarsk KRA
Kuril Is. KUR
Magadan MAG
Manchuria CHM
Primorye PRM
West Siberia WSB
Yakutiya YAK
Alaska ASK NORTHERN AMERICA
Alberta ABT
Aleutian Is. ALU
British Columbia BRC
Northwest Territories NWT
Yukon YUK
Finland FIN EUROPE
North European Russia RUN
Norway NOR
Sweden SWE

Not drawn on the map: Kuril Is., Aleutian Is.. We hold no public-domain boundary for these regions, so they are listed rather than guessed at.

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 117 in flower of 120 examined

Proportion of examined Polemonium villosum in flower, by month
Month In flower Examined Share 95% interval
Jan 0 0 too few examined
Feb 0 0 too few examined
Mar 0 0 too few examined
Apr 0 0 too few examined
May 4 4 too few examined
Jun 29 29 100% 88% to 100%
Jul 68 70 97% 90% to 99%
Aug 16 17 94% 73% to 99%
Sep 0 0 too few examined
Oct 0 0 too few examined
Nov 0 0 too few examined
Dec 0 0 too few examined

Peak flowering in Jun. Each bar is the share of Polemonium villosum 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. 117 of 120 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 9 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.

Where it actually grows measured, from 1,448 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -30.7 °C -20.6 °C -7.5 °C
Warmest month, mean daily high 9.0 °C 15.6 °C 22.1 °C
Annual rainfall 380 mm 708 mm 1,840 mm
Rainfall in the driest quarter 38 mm 85 mm 294 mm

It is found where winters are arctic. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,448 research-grade observations of Polemonium villosum 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 18 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.

  • Polemonium acutiflorum Willd.
  • Polemonium acutiflorum f. lacteum Lepage
  • Polemonium acutiflorum subsp. diminutum (Klokov) Kamelin
  • Polemonium caeruleum lus. racemosum Regel
  • Polemonium caeruleum subsp. villosum (Rudolph ex Georgi) Brand
  • Polemonium caeruleum var. acutiflorum (Willd. ex Roem. & Schult.) Ledeb.
  • Polemonium caeruleum var. lofoticum Brand
  • Polemonium caeruleum var. racemosum (Regel) Miyabe & Kudô
  • Polemonium caeruleum var. villosum (Rudolph ex Georgi) Brand
  • Polemonium caeruleum var. vulgare Hook.
  • Polemonium campanulatum H.Lindb. ex Lindm.
  • Polemonium coeruleum var. subalpinum Polozhij
  • Polemonium diminutum Klokov
  • Polemonium foliolatum Klokov
  • Polemonium lofoticum (Brand) Klokov
  • Polemonium racemosum (Regel) Kitam.
  • Polemonium villosum f. glabrum (S.D.Zhao) Y.C.Chu
  • Polemonium villosum var. glabrum S.D.Zhao

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. USDA PLANTS Database. common name, checklist symbol POAC. public domain. 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.