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Polygala amarella; photograph (c) Alexis Tinker-Tsavalas, some rights reserved (CC BY) CC BY(c) Alexis Tinker-Tsavalas, some rights reserved (CC BY) · observed growing wild · 2026-06-16

Polygala amarella Crantz

Dwarf Milkwort

Polygalaceae · Denmark, Finland +23

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Polygala amarella, photograph (c) Ljaž, some rights reserved (CC BY)Polygala amarella, photograph (c) Ljaž, some rights reserved (CC BY)Polygala amarella, photograph (c) Ljaž, some rights reserved (CC BY)Polygala amarella, photograph (c) Ljaž, some rights reserved (CC BY)Polygala amarella, photograph (c) Milan Chytrý, some rights reserved (CC BY)Polygala amarella, photograph (c) Alexis Tinker-Tsavalas, some rights reserved (CC BY) 104 photographs ›
Habitat figures
Cold floor (1 night in 100)
-19.0°C
Record low -30.4 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
20°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
909mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
5–36DLI
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

Polygala amarella (or P. amara), commonly known as dwarf milkwort or Kentish milkwort, is a plant of the family Polygalaceae. A European native, it grows on chalky grass land and limestone mountain pastures.

Quoted from Wikipedia, "Polygala amarella", CC BY-SA 4.0.

About the genus · Polygala

Polygala is a large genus of flowering plants belonging to the family Polygalaceae. They are commonly known as milkworts or snakeroots. The genus is distributed widely throughout much of the world in temperate zones and the tropics. More on Wikipedia ›

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

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (673 mm of 920 mm) takes 8 months, May to December. Mean temperature moves 18.6 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to June.

Rain

920 mm in the median year at the habitat, 673 mm of it May to December. Wettest month July at 97 mm, driest month February at 55 mm. Across the grid cells of the range the year's total runs 592 mm to 1,814 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 909 mm, is the year's rain at the top of the page; the 920 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: 5 to 36 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 1, the highest 90th-percentile month 39).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -19.0 °C, the absolute minimum -30.4 °C, 5,971 frost nights in 44 years, 135.7 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 26.3 °C. Monthly means: the coldest month's mean nightly low -5.0 °C in February (across the grid cells of the range -10.7 °C to -0.6 °C), the warmest month's mean daily high 20.4 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -19.0 °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: 60 to 67% 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 +95 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 Polygala amarella through the yearWarmest months July and August, mean daily high 20 °C; coldest month February, mean nightly low -5.0 °C; 920 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.-40°-30°-20°-10°0°10°20°30°frost26.3° 99th-percentile day, NASA POWER-30.4° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200mm rainDLI 5–36RH 60–67%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 1064 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 °C1 / -5–52 / -4–64 / 0–109 / 5–1415 / 10–1818 / 14–2120 / 17–2320 / 16–2315 / 11–1911 / 5–156 / -1–92 / -4–5
Night °C-5 / -11–0-5 / -11–-1-2 / -7–21 / -4–46 / 1–910 / 5–1213 / 8–1513 / 8–159 / 4–125 / 0–80 / -6–4-3 / -10–1
Rain mm68 / 41–13655 / 32–11865 / 33–13859 / 32–12880 / 39–16789 / 55–17897 / 61–19494 / 60–18979 / 54–15681 / 57–15876 / 55–14577 / 48–158
DLI6 / 2–1012 / 6–1619 / 14–2428 / 24–3234 / 32–3736 / 33–3935 / 31–3829 / 23–3321 / 15–2513 / 7–177 / 2–115 / 1–8
RH %66 / 59–7065 / 60–6962 / 59–6560 / 58–6260 / 56–6260 / 57–6360 / 58–6362 / 59–6463 / 61–6565 / 62–6867 / 62–7067 / 60–71
How this section is made
Each figure is the median across the 1064 grid cells on land that hold in-range records (1254 records in those cells; 11 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 633:3875 (58.325, 13.775). Over 44 years there: absolute minimum -30.4 °C, 1st-percentile night -19.0 °C, 99th-percentile day 26.3 °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 1064 distinct grid cells holding 1254 of the 1265 in-range records (11 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 633:3875 (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 58.50_13.750, lapse-corrected +95 m at 6.5 °C/km. Elevation: ETOPO 2022, 217 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.
NativeDenmark, Finland, Great Britain, Norway, Sweden, Austria, Belgium, Czechoslovakia, Germany, Hungary, Poland, Switzerland, France, Bulgaria, Italy, Romania, Yugoslavia, Belarus, Baltic States, Central European Russia, East European Russia, North European Russia, Northwest European Russia, Ukraine, West Siberia · 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 marker47.87, 11.04 · in the densest population, 603 records (36% 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 1693 georeferenced records inside the native range; the climate across the range on the 1254 of them in the land cells it reads, of 1265 placed to within 10 km; the map shows only the 1418 openly licensed ones, which alone would put the marker 27 km away. 1 record outside the WCVP native range not used. 428 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 1693 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Polygala amarella, photograph 1did not loadPolygala amarella, photograph 2did not loadPolygala amarella, photograph 3did not loadPolygala amarella, photograph 4did not loadPolygala amarella, photograph 5did not loadPolygala amarella, photograph 6did not load

Photographs: (c) Ljaž, some rights reserved (CC BY) (4); (c) Milan Chytrý, some rights reserved (CC BY); (c) Alexis Tinker-Tsavalas, some rights reserved (CC BY).

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

Epipactis atrorubens Epipactis atrorubens Dark-red Helleborine Photo: CC BY, Antoine ThivolleCampanula rotundifolia Campanula rotundifolia Harebell Photo: CC0, author not statedSchoenus ferrugineus Schoenus ferrugineus Brown Bog-rush Photo: CC BY-SA, Nicholas WeiVaccinium vitis-idaea Vaccinium vitis-idaea Cowberry Photo: CC BY, Scott ShanksNardus stricta Nardus stricta Mat-grass Photo: CC BY, Andreas SchneiderEriophorum vaginatum Eriophorum vaginatum Tussock cottongrass Photo: CC BY, Matt Berger

Other Polygala 13 in the reference

Polygala amara Polygala amara Milkwort Photo: CC BY-SA, xulescu_gPolygala arillata Polygala arillata Polygalaceae Photo: CC BY, Mitch Van DykePolygala calcarea Polygala calcarea Chalk Milkwort Photo: CC BY, Joan SimonPolygala comosa Polygala comosa Tufted milkwort Photo: CC0, author not stated Polygala fallax Polygalaceae Polygala fruticosa Polygala fruticosa Feather Dusters Photo: CC BY, Adele SLPolygala garcini Polygala garcini Dainty Butterfly Bush Photo: CC BY, Cricket RaspetPolygala gazensis Polygala gazensis Polygalaceae Photo: CC BY-SA, Tony RebeloPolygala major Polygala major Polygalaceae Photo: CC BY, Наталья ПикаловаPolygala myrtifolia Polygala myrtifolia Myrtle-leaf milkwort Photo: CC BY, Sixolile FaithPolygala nicaeensis Polygala nicaeensis Polygalaceae Photo: CC BY, Matteo BellucciPolygala virgata Polygala virgata Purple-broom Photo: CC BY, Eryss all 14 ›

Names & registers

Also known as Polygala amara f. austriaca; Polygala amara f. grenieri; Polygala amara f. laxa; Polygala amara f. minutiflora; Polygala amara f. orbicularis and 42 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Polygalaceae
Described by
Crantz
Native to
Denmark, Finland, Great Britain +22
Wild records
1693 in range · 1418 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; 8 records within 1 km of a botanic garden, herbarium or zoo left out (4 at a botanic garden or arboretum, 4 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 58.50_13.750, lapse-corrected +95 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 101 datasets via GBIF.org; each carries its own licence.

Cultifolio

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