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Tolmiea menziesii; photograph Lorax55, CC BY, iNaturalist via GBIF CC BYLorax55, CC BY, iNaturalist via GBIF

Tolmiea menziesii (Pursh) Torr. & A.Gray

Pick-a-back-plant; Youth-on-age; Piggyback plant; Pig-a-back plant

Saxifragaceae · Alaska, British Columbia +2

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Tolmiea menziesii, photograph Harry Podschwit, CC BY, iNaturalist via GBIFTolmiea menziesii, photograph Harry Podschwit, CC BY, iNaturalist via GBIFTolmiea menziesii, photograph William Kimzey, CC BY, iNaturalist via GBIFTolmiea menziesii, photograph William Kimzey, CC BY, iNaturalist via GBIFTolmiea menziesii, photograph William Kimzey, CC BY, iNaturalist via GBIFTolmiea menziesii, photograph James H. Thomas, CC BY, iNaturalist via GBIF 24 photographs ›
Habitat figures
Cold floor (1 night in 100)
-9.5°C
Record low -22.4 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
24°C
Aug at the habitat CHELSA
Rain a year (median across the range)
2,008mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
6–40DLI
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, read as a winter growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Tolmiea menziesii is a species of flowering plant in the family Saxifragaceae. It is known by the common names youth on age, pick-a-back-plant, piggyback plant, and thousand mothers.

Quoted from Wikipedia, "Tolmiea menziesii", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a winter growing season: 70% of the median year's rain (1,469 mm of 1,994 mm) falls in October to March, cooler than the year (wet-season mean 5.8 °C against a yearly mean of 9.9 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: April to September.

Rain

1,994 mm in the median year at the habitat, 1,469 mm of it October to March. Wettest month November at 318 mm, driest month July at 40 mm. Across the grid cells of the range the year's total runs 1,143 mm to 3,429 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 2,008 mm, is the year's rain at the top of the page; the 1,994 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: 6 to 40 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 5, the highest 90th-percentile month 45).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -9.5 °C, the absolute minimum -22.4 °C, 1,894 frost nights in 44 years, 43.0 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 31.4 °C. Monthly means: the coldest month's mean nightly low 0.5 °C in December (across the grid cells of the range -3.5 °C to 3.2 °C), the warmest month's mean daily high 23.8 °C in August (median year across the grid cells of the range, CHELSA). Cold floor: -9.5 °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: 59 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 -137 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 Tolmiea menziesii through the yearWarmest month August, mean daily high 24 °C; coldest month December, mean nightly low 0.5 °C; 1,994 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°frost31.4° 99th-percentile day, NASA POWER-22.4° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400500600mm rainDLI 6–40RH 59–66%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 510 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 / 3–88 / 4–1010 / 6–1213 / 9–1517 / 13–1920 / 15–2223 / 18–2624 / 19–2721 / 17–2314 / 11–179 / 5–115 / 2–7
Night °C1 / -3–41 / -3–33 / -1–54 / 0–67 / 3–910 / 7–1213 / 10–1413 / 10–1411 / 8–137 / 4–93 / -1–61 / -4–3
Rain mm281 / 157–492197 / 107–342197 / 113–335152 / 81–248115 / 66–17491 / 50–14040 / 19–7943 / 22–9284 / 45–152190 / 109–373318 / 184–537286 / 169–475
DLI7 / 6–813 / 11–1420 / 18–2229 / 27–3035 / 33–3737 / 36–4040 / 39–4535 / 34–4027 / 24–3015 / 13–188 / 6–96 / 5–7
RH %65 / 63–6963 / 61–6663 / 61–6561 / 60–6461 / 59–6461 / 58–6559 / 56–6459 / 56–6561 / 57–6463 / 61–6666 / 64–6965 / 62–69
How this section is made
Each figure is the median across the 510 grid cells holding the 861 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 817:1144 (49.125, -122.775). Over 44 years there: absolute minimum -22.4 °C, 1st-percentile night -9.5 °C, 99th-percentile day 31.4 °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 510 distinct grid cells holding 861 of the 861 in-range records; extremes and elevation at the typical cell 817:1144 (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 49.00_-122.500, lapse-corrected -137 m at 6.5 °C/km. Elevation: ETOPO 2022, 12 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, British Columbia, Oregon, Washington · introduced: Føroyar, Great Britain, Ireland, Austria, Netherlands · 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 marker49.208, -122.617 · in the densest population, 596 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 928 georeferenced records inside the native range; the climate across the range on the 861 of them placed to within 10 km; the map shows only the 291 openly licensed ones, which alone would put the marker 14 km away. 506 records outside the WCVP native range not used. 67 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 928 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Tolmiea menziesii, photograph 1did not loadTolmiea menziesii, photograph 2did not loadTolmiea menziesii, photograph 3did not loadTolmiea menziesii, photograph 4did not loadTolmiea menziesii, photograph 5did not loadTolmiea menziesii, photograph 6did not load

Photographs: Harry Podschwit, CC BY, iNaturalist via GBIF (2); William Kimzey, CC BY, iNaturalist via GBIF (3); James H. Thomas, CC BY, iNaturalist via GBIF.

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

Acer circinatum Acer circinatum Vine maple Photo: CC BY, Gavin SlaterDicentra formosa Dicentra formosa Bleeding-heart Photo: CC BY, giantcicadaMahonia nervosa Mahonia nervosa Cascade barberry Photo: CC BY, Alina FisherPolypodium glycyrrhiza Polypodium glycyrrhiza Licorice fern Photo: CC BY, John BrewFrangula purshiana Frangula purshiana Cascara buckthorn Photo: CC BY, Annie KreagerTrillium ovatum Trillium ovatum Pacific trillium Photo: CC BY, Emerson

Other Tolmiea 1 in the reference

Tolmiea diplomenziesii Tolmiea diplomenziesii Piggyback Plant Photo: CC BY, Amelia Tauber

Names & registers

Also known as Heuchera menziesii; Leptaxis menziesii; Ribes hysterix; Tiarella mensiesii; Tiarella menziesii and 1 more. (GBIF Backbone)

Registers not checked Wikidata did not answer when this page was built, so the links it gives (POWO, IPNI, World Flora Online, Wikipedia) were not checked; any shown here are kept from an earlier build. Not asked, or not answered, is not "none": nothing here claims there is none. Why the site says it this way.
GBIFWikipedia

The record

Family
Saxifragaceae
Described by
(Pursh) Torr. & A.Gray
Native to
Alaska, British Columbia, Oregon +1
Wild records
928 in range · 291 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; 23 records within 1 km of a botanic garden, herbarium or zoo left out (15 at a botanic garden or arboretum, 1 at a herbarium, 7 at a zoo; 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 49.00_-122.500, lapse-corrected -137 m at 6.5 °C/km
Wikidata wikidata failedasked 2026-10-22query.wikidata.org 502 (batched: Wikidata's query service, 100 GBIF keys)
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 51 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…