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Eriogonum arborescens; photograph (c) Brian Finzel, some rights reserved (CC BY-SA) CC BY-SA(c) Brian Finzel, some rights reserved (CC BY-SA) · observed growing wild · 2026-05-27

Eriogonum arborescens Greene

Island buckwheat; Santa Cruz Island buckwheat; Santa Cruz Island wild buckwheat

Polygonaceae · California

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Eriogonum arborescens, photograph (c) Matt Berger, some rights reserved (CC BY)Eriogonum arborescens, photograph (c) Rachel Allingham, some rights reserved (CC BY)Eriogonum arborescens, photograph (c) Rachel Allingham, some rights reserved (CC BY)Eriogonum arborescens, photograph (c) Brian Finzel, some rights reserved (CC BY-SA)Eriogonum arborescens, photograph (c) Brian Finzel, some rights reserved (CC BY-SA)Eriogonum arborescens, photograph (c) Brian Finzel, some rights reserved (CC BY-SA) 64 photographs ›
Habitat figures
Coldest month, mean nightly low
11.6°C
Feb and Mar at the habitat, not a floor; extremes not used (sea cell) CHELSA
Warmest month, mean daily high
18°C
Jul, Aug, Sep and Oct at the habitat CHELSA
Rain a year (median across the range)
520mm
6 months of 25 mm or more in the median year CHELSA
Open-sky light
18–52DLI
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

Eriogonum arborescens is a species of wild buckwheat known by the common name Santa Cruz Island buckwheat.

Quoted from Wikipedia, "Eriogonum arborescens", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a winter growing season: 70% of the median year's rain (399 mm of 516 mm) falls in December to March, cooler than the year (wet-season mean 13.0 °C against a yearly mean of 14.8 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: June to September.

Rain

516 mm in the median year at the habitat, 399 mm of it December to March. Wettest month February at 118 mm, driest month July at 1 mm; 4 months under 5 mm. Across the grid cells of the range the year's total runs 413 mm to 620 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 520 mm, is the year's rain at the top of the page; the 516 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 52 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 17, the highest 90th-percentile month 53).

Warmth and air
Temperature

Monthly means: the coldest month's mean nightly low 11.6 °C in February and March (across the grid cells of the range 6.6 °C to 12.5 °C), the warmest month's mean daily high 18.2 °C in September (median year across the grid cells of the range, CHELSA). Cold floor: none read. The nearest figure is 11.6 °C, the coldest month's mean nightly low, February and March, in the median year (CHELSA); a month's mean of its nightly lows is warmer than the nights a floor is read from. The daily extremes were read at a weather cell that is mostly sea and are not used.

Humidity

Relative humidity at the habitat: 56 to 68% 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. CHELSA monthly means, median year across the grid cells of the range. No cold floor is read without a daily extremes series; the coldest month's mean nightly low named in its sentence is not one. 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 Eriogonum arborescens through the yearWarmest months July, August, September and October, mean daily high 18 °C; coldest months February and March, mean nightly low 11.6 °C; 516 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA. Habitat months, northern hemisphere.0°5°10°15°20°25°30°°C · day and nightcold quarter0255075100125150mm rainDLI 18–52RH 56–68%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 46 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C14 / 13–1714 / 13–1714 / 13–1814 / 13–2115 / 14–2316 / 15–2518 / 16–2718 / 17–2818 / 17–2718 / 17–2316 / 15–2014 / 13–17
Night °C12 / 6–1312 / 7–1312 / 8–1312 / 9–1313 / 11–1414 / 13–1516 / 15–1717 / 16–1816 / 15–1716 / 12–1614 / 8–1512 / 6–13
Rain mm115 / 82–140118 / 94–14081 / 69–9932 / 27–409 / 8–122 / 1–31 / 0–12 / 1–24 / 3–520 / 15–2747 / 37–5685 / 64–103
DLI20 / 19–2226 / 24–2735 / 34–3745 / 43–4650 / 48–5052 / 51–5350 / 50–5147 / 46–4739 / 38–4130 / 29–3223 / 21–2418 / 17–20
RH %57 / 54–6158 / 56–6261 / 57–6461 / 55–6665 / 57–7267 / 56–7868 / 56–8466 / 55–8464 / 54–7761 / 53–6657 / 52–6156 / 52–60

The daily extremes were read at a NASA POWER cell that is 24% land: neither it nor the next candidates whose coldest month's mean nightly low is within 2 °C of the median across cells sit in a POWER cell that is mostly land, and the rule reads a cold floor only from a cell that is mostly land, so none is read for this species. Nor is the coldest month's mean nightly low taken as one: it is a mean of a month's lows, not its coldest night. What that cell gave over 44 years: absolute minimum 4.5 °C, 1st-percentile night 8.8 °C, 99th-percentile day 23.7 °C.

How this section is made
Each figure is the median across the 46 grid cells on land that hold in-range records (437 records in those cells; 3 more cells hold records but no land by the elevation layer, so those records sit at sea and the cells are left out), 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 1120:1196 (33.975, -120.175). 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 46 distinct grid cells holding 437 of the 459 in-range records (3 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 1120:1196 (its coldest month's mean nightly low nearest the median across cells, though its NASA POWER cell is only 24% land and none of the 11 next candidates within 2 °C of the median was mostly land); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 34.00_-120.000, lapse-corrected +106 m at 6.5 °C/km. Elevation: ETOPO 2022, 152 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 marker34.017, -119.717 · in the densest population, 505 records (97% 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 519 georeferenced records inside the native range; the climate across the range on the 437 of them in the land cells it reads, of 459 placed to within 10 km; the map shows only the 147 openly licensed ones, which alone would put the marker 1 km away. 1 record outside the WCVP native range not used. 60 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 519 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Eriogonum arborescens, photograph 1did not loadEriogonum arborescens, photograph 2did not loadEriogonum arborescens, photograph 3did not loadEriogonum arborescens, photograph 4did not loadEriogonum arborescens, photograph 5did not loadEriogonum arborescens, photograph 6did not load

Photographs: (c) Matt Berger, some rights reserved (CC BY); (c) Rachel Allingham, some rights reserved (CC BY) (2); (c) Brian Finzel, some rights reserved (CC BY-SA) (3).

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

Heuchera maxima Heuchera maxima Island alumroot Photo: CC BY, Trevor Van LoonDiplacus parviflorus Diplacus parviflorus Island bush monkeyflower Photo: CC BY, Matt BergerHazardia detonsa Hazardia detonsa Island hazardia Photo: CC BY-SA, Brian FinzelArctostaphylos insularis Arctostaphylos insularis Island manzanita Photo: CC BY, Rachel AllinghamDudleya candelabrum Dudleya candelabrum Candleholder dudleya Photo: CC BY, Casey H. RichartCastilleja hololeuca Castilleja hololeuca Island paintbrush Photo: CC BY, Devon Bradley

Other Eriogonum 56 in the reference

Eriogonum abertianum Eriogonum abertianum Abert's wild buckwheat Photo: CC0, author not statedEriogonum alatum Eriogonum alatum Winged eriogonum Photo: CC BY-SA, lejones417Eriogonum allenii Eriogonum allenii Shale barren buckwheat Photo: CC BY, Harold SmithEriogonum annuum Eriogonum annuum Annual wild buckwheat Photo: CC0, author not statedEriogonum arcuatum Eriogonum arcuatum Curved Buckwheat Photo: CC BY, Anders HastingsEriogonum brevicaule Eriogonum brevicaule Shortstem buckwheat Photo: CC0, author not statedEriogonum caespitosum Eriogonum caespitosum Matted wild buckwheat Photo: CC BY, htasoffEriogonum cinereum Eriogonum cinereum Ashy buckwheat Photo: CC0, author not statedEriogonum compositum Eriogonum compositum Arrow-leaf Wild Buckwheat Photo: CC0, author not statedEriogonum corymbosum Eriogonum corymbosum Corymbed buckwheat Photo: CC BY, Anders HastingsEriogonum crocatum Eriogonum crocatum Saffron wild buckwheat Photo: CC0, author not statedEriogonum deflexum Eriogonum deflexum Skeleton-weed Photo: CC BY, CK2AZ all 57 ›

Names & registers

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Polygonaceae
Described by
Greene
Native to
California
Wild records
519 in range · 147 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 34.00_-120.000, lapse-corrected +106 m at 6.5 °C/km; read, and set aside: NASA POWER's cell is mostly sea (24% land), so no cold floor is shown
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 24 datasets via GBIF.org; each carries its own licence.

Cultifolio

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