Hypericum ascyronL.

great St. Johnswort

WFO wfo-0000727365 Accepted WFO 2026-06 8 photographs CC BY

Plate 1 figs. a–h · 8 separate observations

Hypericum ascyron, photographed by Ryan Sorrells
fig. a Ryan Sorrells, CC BY 4.0 / 2021-09-12 / obs. 156994551

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.

The specimen a real sheet, in a real collection

Herbarium
Smithsonian, US National Herbarium
Accession
US 3079930
Filed as
Hypericum ascyron subsp. pyramidatum (Dryand. ex Aiton) N.Robson
Det. by
Strong, Mark T., (BOT), Smithsonian Institution - National Museum of Natural History (UNITED STATES)
Collected
L. E. Hicks
Origin
US
The sheet
View the digitised specimen (CC0 1.0)

A real pressed plant, in a real collection, under the accession number above. Not an illustration of one. The holding institution does not serve this sheet’s image to third parties, so there is no photograph here. The record is real and the link goes to it. Where we hold no openly licensed sheet for a species this section is simply absent, and where a sheet never recorded who determined it, that field stays empty rather than being filled in. Roughly half of all herbarium sheets never recorded a determiner, which is ordinary.

Native range 47 botanical countries

Regions where Hypericum ascyron is native: Altay, Amur, Buryatiya, China North-Central, China South-Central, China Southeast, Chita, Hainan, Inner Mongolia, Irkutsk, Japan, Kamchatka, Kazakhstan, Khabarovsk, Korea, Krasnoyarsk, Kuril Is., Manchuria, Mongolia, Primorye, Qinghai, Sakhalin, Taiwan, Tuva, West Siberia, Xinjiang, Yakutiya, Vietnam, Connecticut, Illinois, Indiana, Iowa, Kansas, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New York, Ohio, Ontario, Pennsylvania, Québec, Vermont, Wisconsin AltayAmurBuryatiyaChina North-CentralChina South-CentralChina SoutheastChitaHainanInner MongoliaIrkutskJapanKamchatkaKazakhstanKhabarovskKrasnoyarskManchuriaMongoliaPrimoryeQinghaiSakhalinTaiwanTuvaWest SiberiaXinjiangYakutiyaVietnamConnecticutIllinoisIndianaIowaKansasMaineMarylandMassachusettsMichiganMinnesotaMissouriNew HampshireNew YorkOhioOntarioPennsylvaniaQuébecVermontWisconsin Korea
Native distribution of Hypericum ascyron, 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
Altay ALT ASIA-TEMPERATE
Amur AMU
Buryatiya BRY
China North-Central CHN
China South-Central CHC
China Southeast CHS
Chita CTA
Hainan CHH
Inner Mongolia CHI
Irkutsk IRK
Japan JAP
Kamchatka KAM
Kazakhstan KAZ
Khabarovsk KHA
Korea KOR
Krasnoyarsk KRA
Kuril Is. KUR
Manchuria CHM
Mongolia MON
Primorye PRM
Qinghai CHQ
Sakhalin SAK
Taiwan TAI
Tuva TVA
West Siberia WSB
Xinjiang CHX
Yakutiya YAK
Connecticut CNT NORTHERN AMERICA
Illinois ILL
Indiana INI
Iowa IOW
Kansas KAN
Maine MAI
Maryland MRY
Massachusetts MAS
Michigan MIC
Minnesota MIN
Missouri MSO
New Hampshire NWH
New York NWY
Ohio OHI
Ontario ONT
Pennsylvania PEN
Québec QUE
Vermont VER
Wisconsin WIS
Vietnam VIE ASIA-TROPICAL

Not drawn on the map: Kuril Is.. We hold no public-domain boundary for this region, so it is 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 160 in flower of 265 examined

Proportion of examined Hypericum ascyron in flower, by month
Month In flower Examined Share 95% interval
Jan 0 2 too few examined
Feb 0 2 too few examined
Mar 0 5 0% 0% to 43%
Apr 0 3 too few examined
May 0 5 0% 0% to 43%
Jun 9 11 82% 52% to 95%
Jul 139 157 89% 83% to 93%
Aug 12 50 24% 14% to 37%
Sep 0 12 0% 0% to 24%
Oct 0 16 0% 0% to 19%
Nov 0 1 too few examined
Dec 0 1 too few examined

Peak flowering in Jul. Each bar is the share of Hypericum ascyron 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. 160 of 265 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 5 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 1,638 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -25.5 °C -13.0 °C -6.7 °C
Warmest month, mean daily high 21.6 °C 26.9 °C 28.4 °C
Annual rainfall 454 mm 873 mm 1,193 mm
Rainfall in the driest quarter 27 mm 88 mm 213 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 1,638 research-grade observations of Hypericum ascyron 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 38 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.

  • Ascyrum sibiricum Poir.
  • Ascyrum tetragonum Moench
  • Hypericum amplexicaule Lam.
  • Hypericum ascyroides Willd.
  • Hypericum ascyron f. angustifolium Y.Kimura
  • Hypericum ascyron f. vilmorinii (Rehder) Rehder
  • Hypericum ascyron var. adamii R.Keller
  • Hypericum ascyron var. americanum Y.Kimura
  • Hypericum ascyron var. brevistylum Maxim.
  • Hypericum ascyron var. genuinum Maxim.
  • Hypericum ascyron var. giraldii R.Keller
  • Hypericum ascyron var. hupehense Pamp.
  • Hypericum ascyron var. longistylum Maxim.
  • Hypericum ascyron var. macrosepalum Ledeb.
  • Hypericum ascyron var. micropetalum R.Keller
  • Hypericum ascyron var. umbellatum R.Keller
  • Hypericum ascyron var. vilmorinii Rehder
  • Hypericum bartramianum Pursh
  • Hypericum bartramium Mill.
  • Hypericum gebleri Ledeb.
  • Hypericum hemsleyanum H.Lév. & Vaniot
  • Hypericum kelleri H.Lév.
  • Hypericum longifolium H.Lév.
  • Hypericum macrocarpum Michx.

and 14 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.
  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.