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Hypericum fraseri; photograph Michael Wolf, CC BY-SA 3.0, via Wikimedia Commons CC BY-SAMichael Wolf, CC BY-SA 3.0, via Wikimedia Commons

Hypericum fraseri (Spach) Steud.

Hypericaceae · British Columbia, Manitoba +33

English names not checked: Wikidata's common names were not read for this page.

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Hypericum fraseri, photograph Charles de Mille-Isles from Mille-Isles, Canada, CC BY 2.0, via Wikimedia CommonsHypericum fraseri, photograph Joshua Mayer, CC BY-SA 2.0, via Wikimedia CommonsHypericum fraseri, photograph Joshua Mayer from Madison, WI, USA, CC BY-SA 2.0, via Wikimedia CommonsHypericum fraseri, photograph Charles de Mille-Isles from Mille-Isles, Canada, CC BY 2.0, via Wikimedia Commons 5 photographs ›
Habitat figures
Cold floor (1 night in 100)
-27.8°C
Record low -42.4 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
24°C
Jul at the habitat CHELSA
Rain a year (median across the range)
969mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
8–39DLI
Lowest to highest month (DLI) CHELSA
The year in your months, northern hemisphere
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
Rain spread: 70% of the median year's rain takes 8 months, so no short rainy season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Triadenum fraseri, commonly known as bog St. John's wort, Fraser's St. John's wort, and Fraser's marsh St. John's wort, is a perennial flowering plant in the family Hypericaceae that grows in wetlands of Canada and the northern United States. It is named after John Fraser (1750–1811), a Scottish botanist and widely travelled plant collector.

Quoted from Wikipedia, "Hypericum fraseri", CC BY-SA 4.0.

About the genus · Hypericum

Hypericum is a genus of flowering plants in the family Hypericaceae. The genus has a nearly worldwide distribution, missing only from tropical lowlands, deserts and polar regions. Many Hypericum species are regarded as invasive species and noxious weeds. More on Wikipedia ›

Quoted from Wikipedia, "Hypericum", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (746 mm of 1,004 mm) takes 8 months, May to December. Mean temperature moves 29.0 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to June.

Rain

1,004 mm in the median year at the habitat, 746 mm of it May to December. Wettest month June at 105 mm, driest month February at 56 mm. Across the grid cells of the range the year's total runs 764 mm to 1,362 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 969 mm, is the year's rain at the top of the page; the 1,004 mm here is the median year's, the twelve monthly medians added, which the rain rule reads. Habitat calendar, northern hemisphere; median year across the grid cells of the range, CHELSA.

Light

Open sky over the habitat: 8 to 39 mol/m²/day across the year (daily light integral, median year across the grid cells of the range, CHELSA; the lowest 10th-percentile month across the cells is 7, the highest 90th-percentile month 42).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -27.8 °C, the absolute minimum -42.4 °C, 7,518 frost nights in 44 years, 170.9 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 32.5 °C. Monthly means: the coldest month's mean nightly low -13.5 °C in January (across the grid cells of the range -17.4 °C to -7.8 °C), the warmest month's mean daily high 24.1 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -27.8 °C, which is the 1st-percentile night over 44 years at a typical spot in the range (NASA POWER).

Humidity

Relative humidity at the habitat: 56 to 65% across the year (monthly means, median year across the grid cells of the range, CHELSA). A figure about the air, saying nothing about how the plant takes water.

How this section is made

Each card states this species' habitat figures with their sources, and what two fixed rules read from them; nothing here says what the plant does, wants or tolerates. The rules · the terms.

Seasons. Read from the median year of CHELSA monthly rainfall and mean temperature across the grid cells of the range: the rain rule takes the smallest set of months carrying 70% of the rain and calls it winter when its mean is more than half a degree below the year's, summer when more than that above, and neither in between; the temperature rule, used only under 120 mm, names the cooler six months when they are at least a degree cooler than the other six. Months are shifted for the other hemisphere only where the temperature curve moves 4 °C or more and the habitat lies 10° or more from the equator. A reading of the curves, not an observation of the plant.

Rain. CHELSA monthly precipitation, median year across the grid cells of the range. The rain that falls where the species is recorded; nothing about how the plant takes water.

Light. CHELSA shortwave radiation at each envelope cell, a daily-mean flux taken to a daily total and converted at 2.07 mol of PAR per MJ. The sky over the habitat, measured; what reaches a plant under a rock, a shrub or a shade cloth is not.

Temperature. NASA POWER daily minima and maxima over 44 years at a typical spot in the range, lapse-corrected -3 m to its elevation; CHELSA monthly means, median year across the grid cells of the range. The cold floor is the 1st-percentile night named in its sentence. Not a measured survival limit for any plant in a pot.

Humidity. CHELSA relative humidity, median year across the grid cells of the range.

Climate across the habitat

Habitat months, northern hemisphere

Habitat climate of Hypericum fraseri through the yearWarmest month July, mean daily high 24 °C; coldest month January, mean nightly low -13.5 °C; 1,004 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA; the extremes at the edge from NASA POWER. Habitat months, northern hemisphere.-60°-40°-20°0°20°40°frost32.5° 99th-percentile day, NASA POWER-42.4° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0255075100125150mm rainDLI 8–39RH 56–65%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 1094 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low extremes over 44 years at a typical spot in the range, from NASA POWER, marked at the edge, in no month DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C-5 / -9–0-3 / -7–22 / -1–710 / 6–1417 / 12–2022 / 18–2524 / 21–2723 / 21–2619 / 17–2212 / 10–155 / 1–8-2 / -6–2
Night °C-14 / -17–-8-12 / -15–-7-7 / -9–-30 / -2–47 / 5–1013 / 10–1516 / 14–1816 / 14–1812 / 10–145 / 3–8-1 / -4–2-9 / -14–-4
Rain mm67 / 23–10456 / 21–9160 / 32–10775 / 55–11291 / 76–116105 / 82–128101 / 80–12494 / 81–119101 / 87–12092 / 68–12786 / 45–12376 / 29–121
DLI11 / 9–1217 / 16–1825 / 24–2632 / 30–3437 / 35–3939 / 37–4238 / 36–4133 / 31–3525 / 23–2716 / 14–1910 / 8–128 / 7–10
RH %65 / 61–6863 / 59–6559 / 57–6156 / 54–5956 / 55–6058 / 57–6159 / 58–6260 / 59–6361 / 58–6361 / 58–6362 / 59–6564 / 61–69
How this section is made
Each figure is the median across the 1094 grid cells on land that hold in-range records (1319 records in those cells; 5 more cells hold records but no land by the elevation layer, so those records sit at sea and the cells are left out), with the 10th–90th percentile span across those cells after the slash where it differs. A dash is a month one or more of those cells has no figure for in the grid (a variable CHELSA does not carry there), so no median is taken rather than one over fewer cells. Extremes and elevation were read at a typical spot in the range, cell 899:2021 (45.025, -78.925). Over 44 years there: absolute minimum -42.4 °C, 1st-percentile night -27.8 °C, 99th-percentile day 32.5 °C. Normals: CHELSA V2.1 1981–2010 climatology, 0.05° cells (each the mean of ~36 1 km pixels). Across the range: median and 10th–90th percentile of each month across the 1094 distinct grid cells holding 1319 of the 1326 in-range records (5 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 899:2021 (its coldest month's mean nightly low nearest the median across cells); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 45.00_-78.750, lapse-corrected -3 m at 6.5 °C/km. Elevation: ETOPO 2022, 341 m (cell mean).

Natural habitat

Native range as published by WCVP; the marker is where the records are densest and decides nothing: the climate was read across the cells of the in-range records placed well enough to read one, not at the marker.
Openly licensed records inside the range, framed on where they fall.

This species has no GBIF key of its own. Its records are GBIF's under the key of the name Kew's World Checklist holds as this plant: 3189588 (Triadenum fraseri (Spach) Gleason, 2000 records). No name was matched to GBIF; the keys are read from Kew's synonymy. How.

NativeBritish Columbia, Manitoba, Saskatchewan, Labrador, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward I., Québec, Montana, Washington, Illinois, Iowa, Minnesota, Nebraska, Wisconsin, Connecticut, Indiana, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode I., Vermont, West Virginia, Delaware, Maryland, North Carolina, Tennessee, Virginia · introduced: Germany · regions are the level-3 units of the World Geographical Scheme for Recording Plant Distributions, as Kew's World Checklist records ranges, some under historical names such as Yugoslavia or Czechoslovakia (how).
Map marker47.651, -91.608 · in the densest population, 721 records (39% of those in range)
Kew's description“perennial” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1828 georeferenced records inside the native range; the climate across the range on the 1319 of them in the land cells it reads, of 1326 placed to within 10 km; the map shows only the 720 openly licensed ones, which alone would put the marker 1252 km away. 13 records outside the WCVP native range not used. 502 in-range records are placed to worse than 10 km, or with no stated accuracy (admitted only as a person's observation to three decimals), and stay on the map but off the climate.
Other GBIF keysRecords also from GBIF's key 3189588 (Triadenum fraseri (Spach) Gleason): Kew's file holds it as Triadenum fraseri (Spach) Gleason (synonym under Hypericum fraseri (Spach) Steud.); 2,000 records, from GBIF's download.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population inside the densest 4° block of the 1828 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Hypericum fraseri, photograph 1did not loadHypericum fraseri, photograph 2did not loadHypericum fraseri, photograph 3did not loadHypericum fraseri, photograph 4did not load

Photographs: Charles de Mille-Isles from Mille-Isles, Canada, CC BY 2.0, via Wikimedia Commons (2); Joshua Mayer, CC BY-SA 2.0, via Wikimedia Commons; Joshua Mayer from Madison, WI, USA, CC BY-SA 2.0, via Wikimedia Commons.

Similar habitat climate The 6 nearest by mean daily high, mean nightly low and rain, month by month. How.

Nuphar variegata Nuphar variegata Variegated yellow pond-lily Photo: CC0, author not statedParogonum ciliinode Parogonum ciliinode Black-fringed knotweed Photo: CC BY, Abby CionaCarex arctata Carex arctata Drooping woodland sedge Photo: CC0, author not statedLarix laricina Larix laricina American larch Photo: CC BY, Charlie PavlisichSpiranthes casei Spiranthes casei Case's ladies'-tresses Photo: CC BY, Dan RileySolidago hispida Solidago hispida Hairy goldenrod Photo: CC BY, Jenn (McPhee) Dyson

Other Hypericum 106 in the reference

Hypericum acmosepalum Hypericaceae Hypericum adpressum Hypericum adpressum Creeping St. Johnswort Photo: CC BY, Ryan SorrellsHypericum aegypticum Hypericum aegypticum Egyptian St John's wort Photo: CC BY, Milan ChytrýHypericum aethiopicum Hypericum aethiopicum African St Johns Wort Photo: CC BY, Dr. Alexey YakovlevHypericum anagalloides Hypericum anagalloides Tinker's-penny Photo: CC BY, Alexis Tinker-TsavalasHypericum androsaemum Hypericum androsaemum Tutsan Photo: CC BY, Kieran Roy PowellHypericum annulatum Hypericum annulatum Hypericaceae Photo: CC BY-SA, susan brownHypericum ascyron Hypericum ascyron Great St. John's-wort Photo: CC BY, Oleg KosterinHypericum athoum Hypericum athoum Hypericaceae Photo: CC BY-SA, peganum from Henfield, EnglandHypericum balearicum Hypericum balearicum Majorca St John's wort Photo: CC BY, Sheelagh Halsey Hypericum beanii St. Johnswort Hypericum bellum Hypericum bellum Hypericaceae Photo: CC BY-SA, Nick all 107 ›

Names & registers

Also known as Triadenum virginicum var. fraseri; Triadenum virginicum subsp. fraseri; Elodes fraseri; Hypericum virginicum var. fraseri; Triadenum fraseri. (WCVP, RBG Kew)

IPNIPOWOWikidataWFOWikipedia

The record

Family
Hypericaceae
Described by
(Spach) Steud.
Native to
British Columbia, Manitoba, Saskatchewan +32
Wild records
1828 in range · 720 open

Every figure here is derived from public data by a stated rule and names its source; nothing about this species is written for its page by a person or by AI, apart from the marked, credited quotations. How →

Where this page came from built 2026-10-22
Kew's names (WCVP) kew.names answeredas of 2026-06-04Kew's entry Hypericum fraseri (Spach) Steud. (plant_name_id 515505), read from Kew's names file
GBIF species record gbif.species not askedGBIF's backbone holds no one accepted species of this name, and a name it holds only as another species' synonym is not taken for this one, so GBIF's records were not asked
GBIF synonyms gbif.synonyms not askedGBIF's backbone holds no one accepted species of this name, and a name it holds only as another species' synonym is not taken for this one, so GBIF's records were not asked
GBIF common names gbif.vernacular not askedGBIF's backbone holds no one accepted species of this name, and a name it holds only as another species' synonym is not taken for this one, so GBIF's records were not asked
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21this species has no GBIF key of its own; its records are read under GBIF's keys for the names Kew's file holds as this plant, never by a name matched; GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 2000 records of GBIF's key 3189588, Triadenum fraseri (Spach) Gleason (Kew's file holds it as Triadenum fraseri (Spach) Gleason (synonym under Hypericum fraseri (Spach) Steud.)): the GBIF download; 1 record within 1 km of a botanic garden, herbarium or zoo left out (1 at a botanic garden or arboretum; Wikidata's list)
Habitat climate climate answeredasked 2026-10-22
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 45.00_-78.750, lapse-corrected -3 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22found by Kew's IPNI identifier 433442-1, POWO 433442-1
Wikipedia wikipedia answeredasked 2026-10-22
iNaturalist photographs, wild inat.photos.wild not asked
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media not askedGBIF's backbone holds no one accepted species of this name, and a name it holds only as another species' synonym is not taken for this one, so GBIF's records were not asked
Wikimedia Commons commons answeredasked 2026-10-22
OpenAlex papers openalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshot

Every source is recorded as having answered, reported nothing, refused, failed, not been asked, or answered twice where one answer is taken (“not taken: two items answered”), and, for a source asked when this page was built, when: the figures are as the source held them that day; a source read from a file (Kew's World Checklist, a GBIF download) says "as of" the file's day instead; a row carried from an earlier build of the page names that build instead. Only “nothing to report” is ever shown as an absence. Records came from 61 datasets via GBIF.org; each carries its own licence.

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