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Micranthes mertensiana; photograph armeria, CC BY, iNaturalist via GBIF CC BYarmeria, CC BY, iNaturalist via GBIF

Micranthes mertensiana (Bong.) Rosend.

Saxifragaceae · Alaska, Alberta +6

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Micranthes mertensiana, photograph armeria, CC BY, iNaturalist via GBIFMicranthes mertensiana, photograph armeria, CC BY, iNaturalist via GBIFMicranthes mertensiana, photograph armeria, CC BY, iNaturalist via GBIFMicranthes mertensiana, photograph Spencer Quayle, CC0, iNaturalist via GBIFMicranthes mertensiana, photograph Spencer Quayle, CC0, iNaturalist via GBIFMicranthes mertensiana, photograph Spencer Quayle, CC0, iNaturalist via GBIF 24 photographs ›
Habitat figures
Cold floor (1 night in 100)
-17.4°C
Record low -26.8 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
22°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,928mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
7–45DLI
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 winters: the rain comes October to March, with nights below freezing; no growing season read. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Micranthes mertensiana, the wood saxifrage or Mertens' saxifrage, is a species of flowering plant in the Saxifragaceae family. It is a subshrub native to western North America, which ranges from Alaska to Montana and California. It grows on mossy rocks and cliffs in subalpine areas. In California it grows in the Klamath Ranges, outer North Coast Ranges, and northern and central Sierra Nevada generally above 2,500 metres elevation.

Quoted from Wikipedia, "Micranthes mertensiana", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a rainy season and no growing season: 70% of the median year's rain (1,483 mm of 1,978 mm) falls in October to March, the cooler part of the year, but the mean nightly low is below freezing in February, March, April and January, so the rule reads no growing season from it. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: April to September.

Rain

1,978 mm in the median year at the habitat, 1,483 mm of it October to March. Wettest month December at 323 mm, driest month July at 37 mm. Across the grid cells of the range the year's total runs 1,103 mm to 3,697 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,928 mm, is the year's rain at the top of the page; the 1,978 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: 7 to 45 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 4, the highest 90th-percentile month 51).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -17.4 °C, the absolute minimum -26.8 °C, 4,051 frost nights in 44 years, 92.1 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 31.1 °C. Monthly means: the coldest month's mean nightly low -2.5 °C in December (across the grid cells of the range -12.9 °C to 2.7 °C), the warmest month's mean daily high 22.2 °C in August (median year across the grid cells of the range, CHELSA). Cold floor: -17.4 °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 66% 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 -347 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 Micranthes mertensiana through the yearWarmest months July and August, mean daily high 22 °C; coldest month December, mean nightly low -2.5 °C; 1,978 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°40°frost31.1° 99th-percentile day, NASA POWER-26.8° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400500600mm rainDLI 7–45RH 56–66%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 643 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 °C3 / -6–105 / -3–127 / 0–1310 / 3–1614 / 8–2018 / 13–2422 / 16–2822 / 16–2919 / 12–2513 / 6–196 / -2–133 / -7–10
Night °C-2 / -12–3-2 / -11–3-1 / -8–41 / -6–54 / -2–88 / 3–1111 / 6–1411 / 6–149 / 2–125 / -3–90 / -9–5-3 / -13–3
Rain mm284 / 126–491219 / 95–353203 / 95–344139 / 72–245115 / 52–17890 / 23–15737 / 6–10739 / 9–12875 / 20–199161 / 72–463293 / 137–545323 / 133–513
DLI8 / 5–1314 / 10–1822 / 18–2731 / 27–3737 / 34–4441 / 36–4945 / 36–5139 / 31–4529 / 22–3617 / 11–259 / 5–147 / 4–11
RH %65 / 61–6863 / 60–6663 / 59–6561 / 57–6461 / 56–6460 / 54–6557 / 49–6656 / 48–6657 / 51–6461 / 55–6666 / 60–6965 / 61–69
How this section is made
Each figure is the median across the 643 grid cells holding the 1063 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 809:1148 (49.525, -122.575). Over 44 years there: absolute minimum -26.8 °C, 1st-percentile night -17.4 °C, 99th-percentile day 31.1 °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 643 distinct grid cells holding 1063 of the 1063 in-range records; extremes and elevation at the typical cell 809:1148 (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 49.50_-122.500, lapse-corrected -347 m at 6.5 °C/km. Elevation: ETOPO 2022, 393 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.
NativeAlaska, Alberta, British Columbia, Idaho, Montana, Oregon, Washington, California · 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 marker45.586, -122.155 · in the densest population, 633 records (46% of those in range)
Kew's description“subshrub” · “subalpine or subarctic” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1383 georeferenced records inside the native range; the climate across the range on the 1063 of them placed to within 10 km; the map shows only the 563 openly licensed ones, which alone would put the marker 11 km away. 2 records outside the WCVP native range not used. 320 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 1383 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Micranthes mertensiana, photograph 1did not loadMicranthes mertensiana, photograph 2did not loadMicranthes mertensiana, photograph 3did not loadMicranthes mertensiana, photograph 4did not loadMicranthes mertensiana, photograph 5did not loadMicranthes mertensiana, photograph 6did not load

Photographs: armeria, CC BY, iNaturalist via GBIF (3); Spencer Quayle, CC0, iNaturalist via GBIF (3).

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

Erythranthe decora Erythranthe decora Northwestern monkeyflower Photo: CC BY, Bruce BaileyAllotropa virgata Allotropa virgata Candy-striped allotropa Photo: CC BY, Steven BodzinTiarella trifoliata Tiarella trifoliata Sugar-scoop Photo: CC BY, Daughter DadLilium columbianum Lilium columbianum Columbia lily Photo: CC BY, rosaceae_robertsHemitomes congestum Hemitomes congestum Gnome plant Photo: CC BY, Todd HuangSaxifraga vespertina Saxifraga vespertina Yellowdot saxifrage Photo: CC0, Drew Meyer

Other Micranthes 20 in the reference

Micranthes californica Micranthes californica California saxifrage Photo: CC0, author not statedMicranthes ferruginea Micranthes ferruginea Rusty saxifrage Photo: CC BY-SA, Nick T.Micranthes fusca Micranthes fusca Saxifragaceae Photo: CC BY, Yoshimasa UchiyamaMicranthes hieraciifolia Micranthes hieraciifolia Hawkweed-leaved saxifrage Photo: CC0, author not statedMicranthes integrifolia Micranthes integrifolia Whole-leaved saxifrage Photo: CC BY, J StrakaMicranthes lyallii Micranthes lyallii Lyall's saxifrage Photo: CC BY, scottj800Micranthes manchuriensis Micranthes manchuriensis Manchurian rockfoil Photo: CC BY, Elena_SherehoraMicranthes micranthidifolia Micranthes micranthidifolia Branch lettuce Photo: CC BY, botanygirlMicranthes nelsoniana Micranthes nelsoniana Nelson's saxifrage Photo: CC BY, ivansemenkovMicranthes nivalis Micranthes nivalis Alpine saxifrage Photo: CC BY, Ingvild RiskaMicranthes occidentalis Micranthes occidentalis Western saxifrage Photo: CC BY, Kerstin ReifenrathMicranthes odontoloma Micranthes odontoloma Brook saxifrage Photo: CC BY, Daughter Dad all 21 ›

Names & registers

Also known as Heterisia eastwoodiae; Heterisia mertensiana; Saxifraga eastwoodiae; Saxifraga heterantha; Saxifraga mertensiana and 7 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipedia

The record

Family
Saxifragaceae
Described by
(Bong.) Rosend.
Native to
Alaska, Alberta, British Columbia +5
Wild records
1383 in range · 563 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; 7 records within 1 km of a botanic garden, herbarium or zoo left out (7 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 49.50_-122.500, lapse-corrected -347 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22
Wikipedia wikipedia answeredasked 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 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 63 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…