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Mertensia pterocarpa; photograph KENPEI, CC BY-SA 4.0, via Wikimedia Commons CC BY-SAKENPEI, CC BY-SA 4.0, via Wikimedia Commons

Mertensia pterocarpa (Turcz.) Tatew. & Ohwi

Boraginaceae · Kuril Is., Japan

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Mertensia pterocarpa, photograph peganum from Henfield, England, CC BY-SA 2.0, via Wikimedia CommonsMertensia pterocarpa, photograph peganum from Henfield, England, CC BY-SA 2.0, via Wikimedia CommonsMertensia pterocarpa, photograph peganum from Henfield, England, CC BY-SA 2.0, via Wikimedia CommonsMertensia pterocarpa, photograph peganum from Henfield, England, CC BY-SA 2.0, via Wikimedia CommonsMertensia pterocarpa, photograph sunoochi, CC BY 2.0, via Wikimedia CommonsMertensia pterocarpa, photograph sunoochi, CC BY 2.0, via Wikimedia Commons 10 photographs ›
Habitat figures
Cold floor (1 night in 100)
-20.8°C
Record low -27.7 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
18°C
Aug at the habitat CHELSA
Rain a year (median across the range)
2,133mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
11–34DLI
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
Wet summers: the rain comes May and July to December, read as a summer growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

About the genus · Mertensia

Mertensia is a genus of flowering plants in the borage family Boraginaceae. They are perennial herbaceous plants with blue or sometimes white flowers that open from pink-tinged buds. Such a change in flower color is common in Boraginaceae and is caused by changes in soil pH. More on Wikipedia ›

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

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (1,464 mm of 2,076 mm) falls in May and July to December, warmer than the year (wet-season mean 5.8 °C against a yearly mean of 1.9 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: January to June and November.

Rain

2,076 mm in the median year at the habitat, 1,464 mm of it May and July to December. Wettest month August at 283 mm, driest month February at 105 mm. Across the grid cells of the range the year's total runs 1,671 mm to 2,346 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 2,133 mm, is the year's rain at the top of the page; the 2,076 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: 11 to 34 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 34).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -20.8 °C, the absolute minimum -27.7 °C, 8,483 frost nights in 44 years, 192.8 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 27.0 °C. Monthly means: the coldest month's mean nightly low -15.2 °C in January (across the grid cells of the range -20.2 °C to -4.2 °C), the warmest month's mean daily high 18.4 °C in August (median year across the grid cells of the range, CHELSA). Cold floor: -20.8 °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: 61 to 70% 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 +150 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 Mertensia pterocarpa through the yearWarmest month August, mean daily high 18 °C; coldest month January, mean nightly low -15.2 °C; 2,076 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.-30°-20°-10°0°10°20°30°frost27.0° 99th-percentile day, NASA POWER-27.7° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400mm rainDLI 11–34RH 61–70%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 19 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-9 / -14–-2-8 / -13–-3-3 / -8–-12 / -1–59 / 4–1214 / 7–1717 / 11–2118 / 14–2214 / 10–177 / 4–110 / -5–4-7 / -12–0
Night °C-15 / -20–-4-14 / -19–-5-10 / -15–-3-4 / -8–02 / -2–46 / 4–911 / 7–1412 / 9–159 / 4–112 / -3–7-7 / -12–1-13 / -18–-2
Rain mm142 / 97–172105 / 69–128116 / 98–127112 / 103–132150 / 114–173137 / 94–159218 / 142–258283 / 168–330246 / 181–299199 / 173–228196 / 150–224172 / 120–196
DLI13 / 9–1419 / 14–2027 / 23–2833 / 30–3434 / 32–3432 / 31–3329 / 27–3026 / 25–2722 / 22–2419 / 16–1912 / 10–1311 / 7–12
RH %70 / 59–7467 / 60–7265 / 63–6861 / 60–6762 / 61–7165 / 63–7869 / 66–8169 / 65–7866 / 63–7064 / 62–6667 / 62–7069 / 60–74
How this section is made
Each figure is the median across the 19 grid cells holding the 21 in-range records, 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 938:6446 (43.075, 142.325). Over 44 years there: absolute minimum -27.7 °C, 1st-percentile night -20.8 °C, 99th-percentile day 27.0 °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 19 distinct grid cells holding 21 of the 21 in-range records; extremes and elevation at the typical cell 938:6446 (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 43.00_142.500, lapse-corrected +150 m at 6.5 °C/km. Elevation: ETOPO 2022, 694 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.
NativeKuril Is., Japan · 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 marker43.5, 142.8 · in the densest population, 36 records (64% 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 56 georeferenced records inside the native range; the climate across the range on the 21 of them placed to within 10 km; the map shows only the 51 openly licensed ones, which alone would put the marker 41 km away. 1 record outside the WCVP native range not used. 35 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.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population inside the densest 2° block of the 56 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Mertensia pterocarpa, photograph 1did not loadMertensia pterocarpa, photograph 2did not loadMertensia pterocarpa, photograph 3did not loadMertensia pterocarpa, photograph 4did not loadMertensia pterocarpa, photograph 5did not loadMertensia pterocarpa, photograph 6did not load

Photographs: peganum from Henfield, England, CC BY-SA 2.0, via Wikimedia Commons (4); sunoochi, CC BY 2.0, via Wikimedia Commons (2).

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

Sieversia pentapetala Sieversia pentapetala Rosaceae Photo: CC BY-SA, Miya.mKoenigia weyrichii Koenigia weyrichii Chinese knotweed Photo: CC BY, Saryu Mae 前 朝琉Betula × minor Betula × minor Dwarf white birch Photo: CC0, author not statedAllium ochotense Allium ochotense Far Eastern broad-leaf allium Photo: CC0, author not statedWeigela middendorffiana Weigela middendorffiana Caprifoliaceae Photo: CC BY, turtlecrabLilium debile Lilium debile Slender lily Photo: CC0, author not stated

Other Mertensia 13 in the reference

Mertensia cana Canescent bluebells Mertensia ciliata Mertensia ciliata Mountain bluebells Photo: CC BY, Daughter DadMertensia lanceolata Mertensia lanceolata Lance-leaved bluebells Photo: CC BY, James (Jim) DugganMertensia maritima Mertensia maritima Oysterleaf Photo: CC BY, lengthofcordageMertensia oblongifolia Mertensia oblongifolia Sagebrush bluebells Photo: CC0, author not statedMertensia paniculata Mertensia paniculata Tall bluebells Photo: CC BY, Allison GrayMertensia platyphylla Mertensia platyphylla Broadleaf bluebells Photo: CC0, author not statedMertensia sibirica Mertensia sibirica Siberian bluebells Photo: CC BY-SA, Anneli SaloMertensia simplicissima Mertensia simplicissima Boraginaceae Photo: CC BY, Violetta DzizyurovaMertensia subcordata Mertensia subcordata Boraginaceae Photo: CC BY, Matt BenotschMertensia tweedyi Mertensia tweedyi Boraginaceae Photo: CC BY, Jason GrantMertensia virginica Mertensia virginica Virginia bluebells Photo: CC0, author not stated all 14 ›

Names & registers

Also known as Mertensia pterocarpa f. yoshimurae; Mertensia pterocarpa var. yezoensis; Steenhammera pterocarpa. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidata

The record

Family
Boraginaceae
Described by
(Turcz.) Tatew. & Ohwi
Native to
Kuril Is., Japan
Wild records
56 in range · 51 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
GBIF species record gbif.species answeredasked 2026-10-22
GBIF synonyms gbif.synonyms answeredasked 2026-10-22
GBIF common names gbif.vernacular answeredasked 2026-10-22names fetched 2026-10-22
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21
Habitat climate climate answeredasked 2026-10-22
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 43.00_142.500, lapse-corrected +150 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22
Wikipedia wikipedia nothing to reportasked 2026-10-22
iNaturalist taxon inat.taxon not asked
iNaturalist photographs, wild inat.photos.wild not asked
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media nothing to reportasked 2026-10-22
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 10 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…