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Dioon rzedowskii; photograph C T Johansson, CC BY-SA 4.0, via Wikimedia Commons CC BY-SAC T Johansson, CC BY-SA 4.0, via Wikimedia Commons

Dioon rzedowskii De Luca, A.Moretti, Sabato & Vázq.Torres

Zamiaceae · Mexico Southwest

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Dioon rzedowskii, photograph User:Carstor, CC BY-SA 3.0, via Wikimedia CommonsDioon rzedowskii, photograph C T Johansson, CC BY-SA 4.0, via Wikimedia CommonsDioon rzedowskii, photograph andy_king50, CC BY-SA 3.0, via Wikimedia CommonsDioon rzedowskii, photograph David J. Stang, CC BY-SA 4.0, via Wikimedia CommonsDioon rzedowskii, photograph David J. Stang, CC BY-SA 4.0, via Wikimedia CommonsDioon rzedowskii, photograph David J. Stang, CC BY-SA 4.0, via Wikimedia Commons 10 photographs ›
Habitat figuresfrom few records
Cold floor (1 night in 100)
4.3°C
Record low -5.6 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
26°C
Apr and May at the habitat CHELSA
Rain a year (median across the range)
2,493mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
25–41DLI
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 June to October, read as a summer growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

From few records: 6 records in 5 grid cells. The records.

Summary

Dioon rzedowskii is a species of cycad that is endemic to Oaxaca, Mexico. It occurs in the Rio Santo Domingo valley, near the villages of San Bartolomé Ayautla and San Pedro Teutila.

Quoted from Wikipedia, "Dioon rzedowskii", CC BY-SA 4.0.

About the genus · Dioon

Dioon is a genus of cycads in the family Zamiaceae. It is native to Mexico and Central America. Their habitats include tropical forests, pine-oak forest, and dry hillsides, canyons and coastal dunes.

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

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (1,951 mm of 2,493 mm) falls in June to October, warmer than the year (wet-season mean 19.5 °C against a yearly mean of 18.3 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: December to April.

Rain

2,493 mm in the median year at the habitat, 1,951 mm of it June to October. Wettest month July at 488 mm, driest month March at 45 mm. Across the grid cells of the range the year's total runs 850 mm to 3,177 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 2,493 mm, is the year's rain at the top of the page; the 2,493 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: 25 to 41 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 23, 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 4.3 °C, the absolute minimum -5.6 °C, 8 frost nights in 44 years (NASA POWER daily minima). Warmest: the 99th-percentile day is 35.0 °C. Monthly means: the coldest month's mean nightly low 11.1 °C in January (across the grid cells of the range 7.8 °C to 14.9 °C), the warmest month's mean daily high 26.4 °C in April (median year across the grid cells of the range, CHELSA). Cold floor: 4.3 °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 69% 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 +37 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

From few records: this habitat climate is read from 6 records in 5 grid cells; a page says so under 12 records or 5 cells, and shows the figures as read.

Habitat months, northern hemisphere

Habitat climate of Dioon rzedowskii through the yearWarmest months April and May, mean daily high 26 °C; coldest month January, mean nightly low 11.1 °C; 2,493 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.-10°0°10°20°30°40°frost35.0° 99th-percentile day, NASA POWER-5.6° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400500600mm rainDLI 25–41RH 61–69%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 5 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 °C21 / 17–2323 / 18–2525 / 21–2726 / 22–2826 / 22–2823 / 21–2722 / 20–2623 / 20–2622 / 20–2622 / 19–2521 / 18–2421 / 17–23
Night °C11 / 8–1512 / 9–1613 / 10–1715 / 12–1916 / 13–2017 / 13–2016 / 12–2016 / 13–2016 / 13–2015 / 12–1913 / 10–1712 / 9–16
Rain mm58 / 11–8459 / 11–8545 / 10–6673 / 22–98106 / 77–143377 / 170–467488 / 137–599453 / 143–565415 / 165–517218 / 70–281124 / 23–16377 / 11–107
DLI27 / 25–3331 / 29–3837 / 36–4341 / 40–4540 / 39–4335 / 34–3635 / 34–3735 / 35–3732 / 30–3330 / 28–3328 / 26–3325 / 23–31
RH %64 / 59–6962 / 57–6761 / 55–6461 / 56–6464 / 60–6567 / 65–7067 / 65–7067 / 65–7069 / 67–7268 / 65–7066 / 62–6964 / 60–69
How this section is made
Each figure is the median across the 5 grid cells holding the 6 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 1440:1664 (17.975, -96.775). Over 44 years there: absolute minimum -5.6 °C, 1st-percentile night 4.3 °C, 99th-percentile day 35.0 °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 5 distinct grid cells holding 6 of the 6 in-range records; extremes and elevation at the typical cell 1440:1664 (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 18.00_-96.875, lapse-corrected +37 m at 6.5 °C/km. Elevation: ETOPO 2022, 1444 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.
NativeMexico Southwest · 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 marker18.024, -96.668 · in the densest population, 8 records (80% of those in range)
Kew's description“tree” · “wet tropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 10 georeferenced records inside the native range; the climate across the range on the 6 of them placed to within 10 km, all openly licensed and shown on the map. 1 record outside the WCVP native range not used. Under a dozen records behind the map and the climate. 4 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 10 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Dioon rzedowskii, photograph 1did not loadDioon rzedowskii, photograph 2did not loadDioon rzedowskii, photograph 3did not loadDioon rzedowskii, photograph 4did not loadDioon rzedowskii, photograph 5did not loadDioon rzedowskii, photograph 6did not load

Photographs: User:Carstor, CC BY-SA 3.0, via Wikimedia Commons; C T Johansson, CC BY-SA 4.0, via Wikimedia Commons; andy_king50, CC BY-SA 3.0, via Wikimedia Commons; David J. Stang, CC BY-SA 4.0, via Wikimedia Commons (3).

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

Prosthechea pseudopygmaea Prosthechea pseudopygmaea Orchidaceae Photo: CC BY-SA, Jeanette ClarkeStelis immersa Stelis immersa Sunken Pleurothallis Photo: CC BY, Luc WynMaxillaria meleagris Maxillaria meleagris Orchidaceae Photo: CC BY-SA, Matteo CassellaProsthechea rhynchophora Prosthechea rhynchophora Orchidaceae Photo: CC BY, Neptalí Ramírez MarcialUlmus mexicana Ulmus mexicana Mexican Elm Photo: CC BY, Francisco Emilio Roldán VelascoArpophyllum giganteum Arpophyllum giganteum Orchidaceae Photo: CC BY, Erick Vélez Sánchez

Other Dioon 11 in the reference

Dioon angustifolium Dioon angustifolium Zamiaceae Photo: CC BY, Juan Cruzado CortésDioon califanoi Dioon califanoi Cycad Photo: CC BY-SA, andy_king50Dioon caputoi Dioon caputoi Royal Palm Photo: CC BY-SA, Emőke DénesDioon edule Dioon edule Chestnut Dioon Photo: CC BY, Adrianh M. OrozcoDioon holmgrenii Dioon holmgrenii Sun Palm Photo: CC BY, Carlos Domínguez-RodríguezDioon merolae Dioon merolae Cycad Photo: CC BY, Francisco Emilio Roldán Velasco Dioon pectinatum Zamiaceae Dioon purpusii Dioon purpusii Cycad Photo: CC BY-SA, Eugenio PadillaDioon sonorense Dioon sonorense Virgin’s Palm Photo: CC BY-SA, Krzysztof Ziarnek, KenraizDioon spinulosum Dioon spinulosum Giant Dioon Photo: CC BY, Erick Vélez SánchezDioon tomasellii Dioon tomasellii Palmita Photo: CC0, author not stated

Names & registers

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Zamiaceae
Described by
De Luca, A.Moretti, Sabato & Vázq.Torres
Native to
Mexico Southwest
Wild records
10 in range · 10 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; 9 records within 1 km of a botanic garden, herbarium or zoo left out (9 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 18.00_-96.875, lapse-corrected +37 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22
Wikipedia wikipedia answeredasked 2026-10-22
iNaturalist photographs, wild inat.photos.wild nothing to reportasked 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 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 8 datasets via GBIF.org; each carries its own licence.

Cultifolio

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