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Quercus john-tuckeri; photograph (c) Adam J. Searcy, some rights reserved (CC BY) CC BY(c) Adam J. Searcy, some rights reserved (CC BY) · observed growing wild · 2026-06-29

Quercus john-tuckeri Nixon & C.H.Mull.

Tucker's oak

Fagaceae · California

Cited as Kew's World Checklist cites it, Quercus john-tuckeri Nixon & C.H.Mull.: GBIF's backbone key for this page carries the name with another author, Nixon & C.H.Müll.

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Quercus john-tuckeri, photograph (c) Trevor Van Loon, some rights reserved (CC BY)Quercus john-tuckeri, photograph (c) Trevor Van Loon, some rights reserved (CC BY)Quercus john-tuckeri, photograph (c) Trevor Van Loon, some rights reserved (CC BY)Quercus john-tuckeri, photograph (c) Trevor Van Loon, some rights reserved (CC BY)Quercus john-tuckeri, photograph (c) Trevor Van Loon, some rights reserved (CC BY)Quercus john-tuckeri, photograph (c) Adam J. Searcy, some rights reserved (CC BY) 148 photographs ›
Habitat figures
Cold floor (1 night in 100)
-4.9°C
Record low -10.3 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
31°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
406mm
6 months of 25 mm or more in the median year CHELSA
Open-sky light
18–55DLI
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 December 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

Quercus john-tuckeri is a North American species of oak known by the common name Tucker oak, or Tucker's oak. It is endemic to California, where it grows in the chaparral and oak woodlands of mountain slopes in the western Transverse Ranges, the southernmost Central Coast Ranges, and the margins of the Mojave Desert. The species is named after John M. Tucker, professor of botany (1947–1986) at the University of California, Davis, specialist in Quercus.

Quoted from Wikipedia, "Quercus john-tuckeri", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a winter growing season: 70% of the median year's rain (292 mm of 402 mm) falls in December to March, cooler than the year (wet-season mean 7.7 °C against a yearly mean of 14.3 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: June to September.

Rain

402 mm in the median year at the habitat, 292 mm of it December to March. Wettest month February at 88 mm, driest months (2 at 2 mm); 3 months under 5 mm. Across the grid cells of the range the year's total runs 275 mm to 507 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 406 mm, is the year's rain at the top of the page; the 402 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: 18 to 55 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 16, the highest 90th-percentile month 55).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -4.9 °C, the absolute minimum -10.3 °C, 2,337 frost nights in 44 years, 53.1 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 38.6 °C. Monthly means: the coldest month's mean nightly low 2.0 °C in January and December (across the grid cells of the range -1.7 °C to 4.1 °C), the warmest month's mean daily high 31.3 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -4.9 °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: 44 to 54% 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 +345 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 Quercus john-tuckeri through the yearWarmest months July and August, mean daily high 31 °C; coldest months January and December, mean nightly low 2.0 °C; 402 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.-20°-10°0°10°20°30°40°frost38.6° 99th-percentile day, NASA POWER-10.3° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0255075100125mm rainDLI 18–55RH 44–54%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 197 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 °C13 / 9–1513 / 10–1616 / 13–1820 / 16–2224 / 20–2628 / 25–3031 / 28–3331 / 27–3328 / 24–3023 / 19–2517 / 13–1912 / 9–15
Night °C2 / -2–42 / -1–54 / 0–66 / 2–89 / 6–1213 / 10–1516 / 13–1916 / 13–1914 / 10–1610 / 6–125 / 1–72 / -2–4
Rain mm81 / 52–10888 / 54–10864 / 45–8129 / 20–3610 / 7–122 / 2–42 / 1–53 / 1–66 / 5–920 / 14–2538 / 25–4859 / 40–80
DLI20 / 18–2225 / 23–2735 / 33–3745 / 43–4651 / 50–5255 / 54–5553 / 52–5348 / 47–4941 / 39–4231 / 29–3322 / 20–2418 / 16–20
RH %52 / 47–5754 / 50–5754 / 50–5651 / 48–5348 / 45–5345 / 42–5144 / 41–5044 / 41–5045 / 42–5147 / 44–5149 / 45–5351 / 47–56
How this section is made
Each figure is the median across the 197 grid cells holding the 632 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 1101:1211 (34.925, -119.425). Over 44 years there: absolute minimum -10.3 °C, 1st-percentile night -4.9 °C, 99th-percentile day 38.6 °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 197 distinct grid cells holding 632 of the 632 in-range records; extremes and elevation at the typical cell 1101:1211 (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 35.00_-119.375, lapse-corrected +345 m at 6.5 °C/km. Elevation: ETOPO 2022, 1129 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.
NativeCalifornia · 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 marker34.711, -118.797 · in the densest population, 721 records (89% of those in range)
Kew's description“shrub” · “subtropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 814 georeferenced records inside the native range; the climate across the range on the 632 of them placed to within 10 km; the map shows only the 169 openly licensed ones, which alone would put the marker 2 km away. 182 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 814 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Quercus john-tuckeri, photograph 1did not loadQuercus john-tuckeri, photograph 2did not loadQuercus john-tuckeri, photograph 3did not loadQuercus john-tuckeri, photograph 4did not loadQuercus john-tuckeri, photograph 5did not loadQuercus john-tuckeri, photograph 6did not load

Photographs: (c) Trevor Van Loon, some rights reserved (CC BY) (5); (c) Adam J. Searcy, some rights reserved (CC BY).

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

Malacothamnus fremontii Malacothamnus fremontii Fremon's bushmallow Photo: CC0, author not statedAsclepias californica Asclepias californica California milkweed Photo: CC BY, klickloLessingia glandulifera Lessingia glandulifera Valley lessingia Photo: CC BY, Spencer HurtDiplacus calycinus Diplacus calycinus Kaweah River bush monkeyflower Photo: CC BY, SergeyGalium andrewsii Galium andrewsii Phloxleaf bedstraw Photo: CC BY, klickloEhrendorferia chrysantha Ehrendorferia chrysantha Golden eardrops Photo: CC BY, klicklo

Other Quercus 220 in the reference

Quercus acerifolia Quercus acerifolia Fagaceae Photo: CC BY, Laurel MeredykQuercus acuta Quercus acuta Red-wood evergreen oak Photo: CC BY, Marco MussitaQuercus × acutidens Quercus × acutidens Fagaceae Photo: CC BY, Eric Alan IsaacsonQuercus acutifolia Quercus acutifolia Fagaceae Photo: CC BY, Neptalí Ramírez MarcialQuercus acutissima Quercus acutissima Sawtooth oak Photo: CC BY, Will BurnsideQuercus afares Quercus afares African Oak Photo: CC BY, Mehdi ChetibiQuercus affinis Quercus affinis Fagaceae Photo: CC BY, Neptalí Ramírez MarcialQuercus agrifolia Quercus agrifolia Coast live oak Photo: CC BY, Gregory WadaQuercus alba Quercus alba White oak Photo: CC BY, Jeff ClarkQuercus aliena Quercus aliena Oriental white oak Photo: CC BY, plant 0302Quercus alnifolia Quercus alnifolia Golden Oak Photo: CC BY, Aurelijus Narbutas Quercus × andegavensis Fagaceae all 221 ›

Names & registers

Also known as Quercus turbinella subsp. californica; Quercus turbinella var. californica. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Fagaceae
Described by
Nixon & C.H.Mull.
Native to
California
Wild records
814 in range · 169 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 2880404 is Quercus john-tuckeri Nixon & C.H.Müll.; the page links Kew's Quercus john-tuckeri Nixon & C.H.Mull., 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; 2 records within 1 km of a botanic garden, herbarium or zoo left out (2 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 35.00_-119.375, lapse-corrected +345 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22
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 33 datasets via GBIF.org; each carries its own licence.

Cultifolio

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