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Symphyotrichum boreale; photograph (c) Anders Hastings, some rights reserved (CC BY) CC BY(c) Anders Hastings, some rights reserved (CC BY) · observed growing wild · 2026-09-07

Symphyotrichum boreale (Torr. & A.Gray) Á.Löve & D.Löve

Northern bog aster; Rush aster; Rush-like aster; Slender white aster

Asteraceae · Alaska, Nunavut +34

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Symphyotrichum boreale, photograph (c) Alex Baxter, some rights reserved (CC BY)Symphyotrichum boreale, photograph (c) Alex Baxter, some rights reserved (CC BY)Symphyotrichum boreale, photograph (c) Alex Baxter, some rights reserved (CC BY)Symphyotrichum boreale, photograph (c) Alex Baxter, some rights reserved (CC BY)Symphyotrichum boreale, photograph (c) Anders Hastings, some rights reserved (CC BY)Symphyotrichum boreale, photograph (c) Anders Hastings, some rights reserved (CC BY) 99 photographs ›
Habitat figures
Cold floor (1 night in 100)
-30.9°C
Record low -44.2 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
25°C
Jul at the habitat CHELSA
Rain a year (median across the range)
794mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
8–40DLI
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 April 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.

Summary

Symphyotrichum boreale (formerly Aster borealis) is a species of flowering plant of the aster family (Asteraceae) native to North America. Commonly known as rush aster, northern bog aster, and slender white aster, it is a perennial, herbaceous plant that may reach heights of 85 centimetres (2 feet 9 inches).

Quoted from Wikipedia, "Symphyotrichum boreale", CC BY-SA 4.0.

About the genus · Symphyotrichum

Symphyotrichum is a genus of over 100 species and naturally occurring hybrids of herbaceous annual and perennial plants in the composite family, Asteraceae, most which were formerly treated within the genus Aster. The majority are endemic to North America, but several also occur in the West Indies, Central and South America, as well as one species in eastern Eurasia. Several species have been introduced to Europe as garden specimens, most notably New England aster and New York aster.

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

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (576 mm of 760 mm) falls in April to October, warmer than the year (wet-season mean 13.3 °C against a yearly mean of 5.4 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: October to April.

Rain

760 mm in the median year at the habitat, 576 mm of it April to October. Wettest month June at 95 mm, driest month February at 26 mm. Across the grid cells of the range the year's total runs 480 mm to 1,011 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 794 mm, is the year's rain at the top of the page; the 760 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: 8 to 40 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 4, the highest 90th-percentile month 43).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -30.9 °C, the absolute minimum -44.2 °C, 8,573 frost nights in 44 years, 194.8 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 29.8 °C. Monthly means: the coldest month's mean nightly low -13.6 °C in January (across the grid cells of the range -21.7 °C to -8.4 °C), the warmest month's mean daily high 24.8 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -30.9 °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: 55 to 65% 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 -41 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 Symphyotrichum boreale through the yearWarmest month July, mean daily high 25 °C; coldest month January, mean nightly low -13.6 °C; 760 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.-60°-40°-20°0°20°40°frost29.8° 99th-percentile day, NASA POWER-44.2° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0255075100125mm rainDLI 8–40RH 55–65%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 791 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 °C-5 / -15–-1-3 / -11–13 / -3–711 / 5–1417 / 11–2022 / 17–2525 / 21–2824 / 19–2619 / 14–2212 / 6–154 / -3–8-3 / -11–1
Night °C-14 / -22–-8-12 / -18–-8-7 / -13–-30 / -5–37 / 2–1013 / 7–1516 / 10–1816 / 10–1811 / 5–144 / -2–7-3 / -10–1-11 / -17–-5
Rain mm29 / 17–8226 / 14–6742 / 20–6763 / 26–8780 / 43–9995 / 65–12193 / 66–11186 / 57–10988 / 44–10371 / 33–9951 / 22–9536 / 18–91
DLI10 / 6–1217 / 12–1925 / 22–2732 / 31–3537 / 36–4040 / 37–4340 / 35–4334 / 29–3625 / 19–2816 / 11–1910 / 6–128 / 4–10
RH %65 / 62–7063 / 60–6759 / 56–6255 / 53–5955 / 53–5957 / 55–6058 / 54–6159 / 55–6159 / 56–6159 / 57–6262 / 59–6664 / 61–71
How this section is made
Each figure is the median across the 791 grid cells on land that hold in-range records (1029 records in those cells; 1 more cell holds records but no land by the elevation layer, so those records sit at sea and the cell is 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 735:1308 (53.225, -114.575). Over 44 years there: absolute minimum -44.2 °C, 1st-percentile night -30.9 °C, 99th-percentile day 29.8 °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 791 distinct grid cells holding 1029 of the 1030 in-range records (1 further cell with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 735:1308 (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 53.00_-114.375, lapse-corrected -41 m at 6.5 °C/km. Elevation: ETOPO 2022, 828 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.
NativeAlaska, Nunavut, Northwest Territories, Yukon, Alberta, British Columbia, Manitoba, Saskatchewan, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward I., Québec, Colorado, Idaho, Montana, Washington, Wyoming, Illinois, Iowa, Minnesota, North Dakota, Nebraska, South Dakota, Wisconsin, Indiana, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Vermont, West Virginia · 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 marker42.831, -88.457 · in the densest population, 623 records (37% 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 1674 georeferenced records inside the native range; the climate across the range on the 1029 of them in the land cells it reads, of 1030 placed to within 10 km; the map shows only the 1006 openly licensed ones, which alone would put the marker 396 km away. 2 records outside the WCVP native range not used. 644 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.
Other GBIF keysRecords also from GBIF's key 3151492 (Symphyotrichum boreale (Torr. & A.Gray) A.LÃ): Kew's file holds it as Symphyotrichum boreale (Torr. & A.Gray) Á.Löve & D.Löve (accepted); 0 records, from GBIF's search API on the day of the build.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population inside the densest 4° block of the 1674 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Symphyotrichum boreale, photograph 1did not loadSymphyotrichum boreale, photograph 2did not loadSymphyotrichum boreale, photograph 3did not loadSymphyotrichum boreale, photograph 4did not loadSymphyotrichum boreale, photograph 5did not loadSymphyotrichum boreale, photograph 6did not load

Photographs: (c) Alex Baxter, some rights reserved (CC BY) (4); (c) Anders Hastings, some rights reserved (CC BY) (2).

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

Salix serissima Salix serissima Autumn willow Photo: CC BY, Dustin SniderPotamogeton richardsonii Potamogeton richardsonii Richardson's pondweed Photo: CC BY, Robyn PerkinsBetula pumila Betula pumila Bog birch Photo: CC0, author not statedSchizachne purpurascens Schizachne purpurascens Purple false melic Photo: CC0, author not statedLilium philadelphicum Lilium philadelphicum Wood lily Photo: CC0, author not statedZizania palustris Zizania palustris Northern wildrice Photo: CC BY, Lorna Grant

Other Symphyotrichum 56 in the reference

Symphyotrichum adnatum Symphyotrichum adnatum Scale-leaf aster Photo: CC0, author not statedSymphyotrichum anomalum Symphyotrichum anomalum Many-ray aster Photo: CC0, author not statedSymphyotrichum anticostense Symphyotrichum anticostense Anticosti Island aster Photo: CC0, author not statedSymphyotrichum ascendens Symphyotrichum ascendens Western aster Photo: CC BY, Daughter DadSymphyotrichum campestre Symphyotrichum campestre Western meadow aster Photo: CC BY, Anders HastingsSymphyotrichum chilense Symphyotrichum chilense Pacific aster Photo: CC0, author not statedSymphyotrichum ciliolatum Symphyotrichum ciliolatum Lindley's aster Photo: CC BY, Robyn PerkinsSymphyotrichum concolor Symphyotrichum concolor Eastern silver aster Photo: CC BY, carterSymphyotrichum cordifolium Symphyotrichum cordifolium Beeweed Photo: CC BY, Alan RockefellerSymphyotrichum divaricatum Symphyotrichum divaricatum Slimaster Photo: CC BY, Chris StahlSymphyotrichum drummondii Symphyotrichum drummondii Drummond's aster Photo: CC0, author not statedSymphyotrichum dumosum Symphyotrichum dumosum Bushy aster Photo: CC BY, Scott Cave all 57 ›

Names & registers

Also known as Aster aestivus; Aster borealis; Aster eminens; Aster franklinianus; Aster junciformis and 5 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Asteraceae
Described by
(Torr. & A.Gray) Á.Löve & D.Löve
Native to
Alaska, Nunavut, Northwest Territories +33
Wild records
1674 in range · 1006 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 answeredasked 2026-10-22GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 0 records of GBIF's key 3151492, Symphyotrichum boreale (Torr. & A.Gray) A.LÃ (Kew's file holds it as Symphyotrichum boreale (Torr. & A.Gray) Á.Löve & D.Löve (accepted)): GBIF occurrence search API; 8 records within 1 km of a botanic garden, herbarium or zoo left out (5 at a botanic garden or arboretum, 1 at a herbarium, 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 53.00_-114.375, lapse-corrected -41 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 76 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…