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Micranthes petiolaris; photograph author not stated, no rights reserved CC0author not stated, no rights reserved · observed growing wild · 2026-09-13

Micranthes petiolaris (Raf.) Bush

Cliff Saxifrage

Saxifragaceae · West Virginia, Georgia +6

Cited as Kew's World Checklist cites it, Micranthes petiolaris (Raf.) Bush: GBIF's backbone key for this page carries the name with another author, (Raf.) Brouillet & Gornall.

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Micranthes petiolaris, photograph author not stated, no rights reservedMicranthes petiolaris, photograph author not stated, no rights reservedMicranthes petiolaris, photograph author not stated, no rights reservedMicranthes petiolaris, photograph (c) tzeducation, some rights reserved (CC BY)Micranthes petiolaris, photograph (c) tzeducation, some rights reserved (CC BY)Micranthes petiolaris, photograph author not stated, no rights reserved 73 photographs ›
Habitat figures
Cold floor (1 night in 100)
-13.9°C
Record low -26.5 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
26°C
Jul at the habitat CHELSA
Rain a year (median across the range)
1,631mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
15–39DLI
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

Micranthes petiolaris, commonly known as cliff saxifrage, is a species of flowering plant in the saxifrage family. It is native to the Southern Appalachian Mountains where it is found on exposed boulders and rocky seeps, often at high elevation. It is a perennial that produces small white flowers with yellow spots in the summer.

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

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (1,154 mm of 1,642 mm) takes 8 months, February to March, May to September and December. Mean temperature moves 20.2 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to March, June and August to September.

Rain

1,642 mm in the median year at the habitat, 1,154 mm of it February to March, May to September and December. Wettest month July at 158 mm, driest month October at 102 mm. Across the grid cells of the range the year's total runs 1,294 mm to 1,982 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,631 mm, is the year's rain at the top of the page; the 1,642 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: 15 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 13, the highest 90th-percentile month 39).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -13.9 °C, the absolute minimum -26.5 °C, 5,084 frost nights in 44 years, 115.5 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 32.4 °C. Monthly means: the coldest month's mean nightly low -3.5 °C in January (across the grid cells of the range -5.7 °C to -1.0 °C), the warmest month's mean daily high 25.8 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -13.9 °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 63% 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 +97 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 petiolaris through the yearWarmest month July, mean daily high 26 °C; coldest month January, mean nightly low -3.5 °C; 1,642 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°frost32.4° 99th-percentile day, NASA POWER-26.5° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200mm rainDLI 15–39RH 56–63%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 228 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 °C6 / 4–88 / 5–1012 / 9–1517 / 14–2020 / 18–2424 / 21–2726 / 23–2925 / 22–2822 / 19–2517 / 15–2012 / 10–147 / 5–9
Night °C-4 / -6–-1-2 / -5–11 / -1–45 / 3–810 / 8–1314 / 12–1716 / 14–1916 / 14–1913 / 10–167 / 5–103 / 0–5-2 / -4–1
Rain mm133 / 96–172145 / 92–189147 / 113–177131 / 104–154136 / 113–156147 / 118–174158 / 127–186142 / 114–172135 / 105–163102 / 80–130122 / 95–153144 / 100–194
DLI16 / 15–1821 / 20–2228 / 27–2935 / 34–3638 / 37–3939 / 38–3937 / 37–3834 / 33–3429 / 28–3024 / 23–2517 / 16–1915 / 13–16
RH %58 / 57–6058 / 56–5957 / 55–5956 / 55–5860 / 58–6162 / 59–6363 / 60–6563 / 61–6562 / 60–6459 / 58–6058 / 57–5958 / 57–60
How this section is made
Each figure is the median across the 228 grid cells holding the 874 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 1068:1972 (36.575, -81.375). Over 44 years there: absolute minimum -26.5 °C, 1st-percentile night -13.9 °C, 99th-percentile day 32.4 °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 228 distinct grid cells holding 874 of the 874 in-range records; extremes and elevation at the typical cell 1068:1972 (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 36.50_-81.250, lapse-corrected +97 m at 6.5 °C/km. Elevation: ETOPO 2022, 838 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.
NativeWest Virginia, Georgia, Kentucky, Maryland, North Carolina, South Carolina, Tennessee, Virginia · 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 marker35.658, -82.486 · in the densest population, 998 records (89% 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 1121 georeferenced records inside the native range; the climate across the range on the 874 of them placed to within 10 km; the map shows only the 286 openly licensed ones, which alone would put the marker 27 km away. 1 record outside the WCVP native range not used. 247 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 of the 1121 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 petiolaris, photograph 1did not loadMicranthes petiolaris, photograph 2did not loadMicranthes petiolaris, photograph 3did not loadMicranthes petiolaris, photograph 4did not loadMicranthes petiolaris, photograph 5did not loadMicranthes petiolaris, photograph 6did not load

Photographs: author not stated, no rights reserved · CC0 (4); (c) tzeducation, some rights reserved (CC BY) (2).

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

Melanthium parviflorum Melanthium parviflorum Appalachian bunchflower Photo: CC BY, Scott WardSolidago curtisii Solidago curtisii Mountain decumbent goldenrod Photo: CC0, author not statedHoustonia serpyllifolia Houstonia serpyllifolia Thymeleaf bluet Photo: CC BY, Kristály Cravens-LiszakEubotrys recurvus Eubotrys recurvus Ericaceae Photo: CC BY, Jason HollingerEutrochium steelei Eutrochium steelei Appalachian Joe-Pye weed Photo: CC0, author not statedThalictrum clavatum Thalictrum clavatum Mountain meadow-rue Photo: CC0, author not stated

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 mertensiana Micranthes mertensiana Saxifragaceae Photo: CC BY, armeriaMicranthes 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 Reifenrath all 21 ›

Names & registers

Also known as Hexaphoma petiolaris; Hydatica petiolaris; Micranthes petiolaris var. petiolaris; Saxifraga leucanthemifolia; Saxifraga michauxii and 4 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Saxifragaceae
Described by
(Raf.) Bush
Native to
West Virginia, Georgia, Kentucky +5
Wild records
1121 in range · 286 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 2026-10-22GBIF's key 8183560 is Micranthes petiolaris (Raf.) Brouillet & Gornall; the page links Kew's Micranthes petiolaris (Raf.) Bush, and the name is cited as Kew cites it
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 36.50_-81.250, lapse-corrected +97 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22IPNI and POWO linked by Kew's number for Micranthes petiolaris (Raf.) Bush (the item's: IPNI 791917-1, POWO 160069-2)
Wikipedia wikipedia answeredasked 2026-10-22
iNaturalist photographs, wild inat.photos.wild answeredasked 2026-10-22from iNaturalist's open data of 2026-09-27: research-grade observations with an open-licence photograph, the 24 whose photographs iNaturalist received last (the open data holds no votes); filled 2026-10-22
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 39 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…