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Helianthemum oelandicum; photograph author not stated, no rights reserved CC0author not stated, no rights reserved · observed growing wild · 2026-08-19

Helianthemum oelandicum (L.) Dum.Cours.

Cistaceae · Ireland, Sweden +24

Cited as Kew's World Checklist cites it, Helianthemum oelandicum (L.) Dum.Cours.: GBIF's backbone key for this page carries the name with another author, (L.) DC.

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Helianthemum oelandicum, photograph (c) Lídia Carrera, some rights reserved (CC BY)Helianthemum oelandicum, photograph (c) Lídia Carrera, some rights reserved (CC BY)Helianthemum oelandicum, photograph (c) Lídia Carrera, some rights reserved (CC BY)Helianthemum oelandicum, photograph (c) Lídia Carrera, some rights reserved (CC BY)Helianthemum oelandicum, photograph (c) jeanjacquesgodon, some rights reserved (CC BY)Helianthemum oelandicum, photograph author not stated, no rights reserved 91 photographs ›
Habitat figures
Cold floor (1 night in 100)
-9.4°C
Record low -17.4 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
24°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,014mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
10–43DLI
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

Helianthemum oelandicum, commonly called hoary rockrose, is a low-growing plant confined to rocky dry calcareous areas especially close to the sea.

Quoted from Wikipedia, "Helianthemum oelandicum", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (761 mm of 1,002 mm) takes 8 months, September to January and April to June. Mean temperature moves 17.0 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: March to July and October to December.

Rain

1,002 mm in the median year at the habitat, 761 mm of it September to January and April to June. Wettest month October at 118 mm, driest month July at 55 mm. Across the grid cells of the range the year's total runs 594 mm to 1,443 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,014 mm, is the year's rain at the top of the page; the 1,002 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: 10 to 43 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 6, the highest 90th-percentile month 46).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -9.4 °C, the absolute minimum -17.4 °C, 3,564 frost nights in 44 years, 81.0 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 25.4 °C. Monthly means: the coldest month's mean nightly low -1.2 °C in February (across the grid cells of the range -9.3 °C to 2.1 °C), the warmest month's mean daily high 23.9 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -9.4 °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: 57 to 61% 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 -3 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 Helianthemum oelandicum through the yearWarmest months July and August, mean daily high 24 °C; coldest month February, mean nightly low -1.2 °C; 1,002 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°frost25.4° 99th-percentile day, NASA POWER-17.4° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200mm rainDLI 10–43RH 57–61%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 704 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 / -1–107 / 0–1111 / 3–1413 / 5–1717 / 10–2121 / 14–2524 / 18–2924 / 18–2820 / 14–2415 / 9–1910 / 3–137 / -1–10
Night °C-1 / -10–2-1 / -9–21 / -7–53 / -4–77 / 0–1111 / 4–1514 / 7–1814 / 7–1811 / 4–148 / 0–113 / -6–60 / -9–3
Rain mm78 / 39–11758 / 34–9263 / 36–9994 / 54–13296 / 57–14470 / 40–11955 / 22–9465 / 41–107101 / 56–141118 / 71–173107 / 59–15397 / 50–143
DLI12 / 7–1418 / 12–2127 / 20–3033 / 29–3638 / 34–4142 / 38–4543 / 37–4637 / 31–4028 / 23–3019 / 14–2113 / 8–1510 / 6–12
RH %60 / 56–6759 / 56–6558 / 56–6259 / 56–6260 / 56–6258 / 54–6257 / 52–6157 / 54–6260 / 57–6361 / 59–6561 / 58–6761 / 57–67
How this section is made
Each figure is the median across the 704 grid cells on land that hold in-range records (883 records in those cells; 2 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 670:3929 (56.475, 16.475). Over 44 years there: absolute minimum -17.4 °C, 1st-percentile night -9.4 °C, 99th-percentile day 25.4 °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 704 distinct grid cells holding 883 of the 885 in-range records (2 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 670:3929 (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 56.50_16.250, lapse-corrected -3 m at 6.5 °C/km. Elevation: ETOPO 2022, 35 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.
NativeIreland, Sweden, Austria, Czechoslovakia, Germany, Poland, Switzerland, France, Spain, Albania, Bulgaria, Greece, Italy, Romania, Sicilia, Yugoslavia, Belarus, Krym, Central European Russia, East European Russia, North European Russia, South European Russia, Ukraine, North Caucasus, Transcaucasus, Turkey · 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 marker44.258, 5.819 · in the densest population, 544 records (59% of those in range)
Kew's description“subshrub” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 927 georeferenced records inside the native range; the climate across the range on the 883 of them in the land cells it reads, of 885 placed to within 10 km; the map shows only the 737 openly licensed ones, which alone would put the marker 11 km away. 43 records outside the WCVP native range not used. 42 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 inside the densest 2° block of the 927 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Helianthemum oelandicum, photograph 1did not loadHelianthemum oelandicum, photograph 2did not loadHelianthemum oelandicum, photograph 3did not loadHelianthemum oelandicum, photograph 4did not loadHelianthemum oelandicum, photograph 5did not loadHelianthemum oelandicum, photograph 6did not load

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

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

Paeonia officinalis Paeonia officinalis Garden peony Photo: CC BY, Thierry ArbaultArtemisia alba Artemisia alba White Mugwort Photo: CC BY, Matteo MartiniArmeria arenaria Armeria arenaria Plumbaginaceae Photo: CC BY, arocheTrinia glauca Trinia glauca Honewort Photo: CC0, author not statedLactuca perennis Lactuca perennis Mountain lettuce Photo: CC BY-SA, Emanuele SantarelliAnthemis cretica Anthemis cretica Mountain Dog-daisy Photo: CC BY, Eleftherios Katsillis

Other Helianthemum 21 in the reference

Helianthemum almeriense Helianthemum almeriense Jarilla Photo: CC BY, Alejandro Rodríguez ZapataHelianthemum apenninum Helianthemum apenninum White rock-rose Photo: CC BY, Thomas DreuxHelianthemum broussonetii Helianthemum broussonetii Cistaceae Photo: CC0, Ina SiebertHelianthemum canariense Helianthemum canariense Cistaceae Photo: CC BY, Sean HartnettHelianthemum canum Helianthemum canum Cistaceae Photo: CC BY, Barry StewartHelianthemum caput-felis Helianthemum caput-felis Cistaceae Photo: CC BY, fmunozHelianthemum cinereum Helianthemum cinereum Cistaceae Photo: CC BY, Christoph MoningHelianthemum croceum Helianthemum croceum Cistaceae Photo: CC BY, fmunozHelianthemum hirtum Helianthemum hirtum Cistaceae Photo: CC BY, Louis AuregliaHelianthemum juliae Helianthemum juliae Cistaceae Photo: CC BY, Diego González DopicoHelianthemum ledifolium Helianthemum ledifolium Cistaceae Photo: CC BY, Bastien AlegotHelianthemum lunulatum Helianthemum lunulatum Cistaceae Photo: CC BY-SA, Krzysztof Ziarnek, Kenraiz all 22 ›

Names & registers

Also known as Cistus coriaceus; Cistus marifolius; Cistus oelandicus; Cistus oelandicus var. canescens; Cistus oelandicus var. denudatus and 23 more. (GBIF Backbone)

Kew accepts as species of their own Helianthemum canum: older names in GBIF's record of this species that Kew's World Checklist accepts as other species. (WCVP, RBG Kew, file of 2026-06-04)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Cistaceae
Described by
(L.) Dum.Cours.
Native to
Ireland, Sweden, Austria +23
Wild records
927 in range · 737 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 7331276 is Helianthemum oelandicum (L.) DC.; the page links Kew's Helianthemum oelandicum (L.) Dum.Cours., 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 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 56.50_16.250, lapse-corrected -3 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-22IPNI and POWO linked by Kew's number for Helianthemum oelandicum (L.) Dum.Cours. (the item's: IPNI 169050-1, POWO 60461866-2)
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 53 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…