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Sisyrinchium angustifolium; photograph (c) Matt Pelikan, some rights reserved (CC BY) CC BY(c) Matt Pelikan, some rights reserved (CC BY) · observed growing wild · 2026-08-01

Sisyrinchium angustifolium Mill.

Narrow-leaf blue-eyed-grass; Narrow-leaved blue-eyed-grass; Blue-eyed grass; Pointed blue-eyed-grass

Iridaceae · Labrador, Newfoundland +40

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Sisyrinchium angustifolium, photograph (c) Matt Pelikan, some rights reserved (CC BY)Sisyrinchium angustifolium, photograph (c) Matt Pelikan, some rights reserved (CC BY)Sisyrinchium angustifolium, photograph (c) Matt Pelikan, some rights reserved (CC BY)Sisyrinchium angustifolium, photograph (c) Matt Pelikan, some rights reserved (CC BY)Sisyrinchium angustifolium, photograph (c) Josiah Londerée, some rights reserved (CC BY)Sisyrinchium angustifolium, photograph (c) Josiah Londerée, some rights reserved (CC BY) 102 photographs ›
Habitat figures
Cold floor (1 night in 100)
-13.9°C
Record low -26.2 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
30°C
Jul at the habitat CHELSA
Rain a year (median across the range)
1,231mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
13–40DLI
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
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

Sisyrinchium angustifolium, commonly known as narrow-leaf blue-eyed-grass, is a herbaceous perennial growing from rhizomes, native to the eastern United States, stretching as far west as Texas and Kansas, where it is the most common blue-eyed grass. It is commonly cultivated as an ornamental.

Quoted from Wikipedia, "Sisyrinchium angustifolium", CC BY-SA 4.0.

About the genus · Sisyrinchium

Sisyrinchium is a large genus of annual to perennial flowering plants in the family Iridaceae. Native to the New World, the species are known as blue-eyed grasses. Although they are not true grasses (Poaceae), they are monocots.

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

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (838 mm of 1,188 mm) takes 8 months, March to October. Mean temperature moves 24.0 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: September to April.

Rain

1,188 mm in the median year at the habitat, 838 mm of it March to October. Wettest month July at 117 mm, driest month February at 79 mm. Across the grid cells of the range the year's total runs 1,024 mm to 1,463 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,231 mm, is the year's rain at the top of the page; the 1,188 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: 13 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 9, the highest 90th-percentile month 41).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -13.9 °C, the absolute minimum -26.2 °C, 4,336 frost nights in 44 years, 98.5 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 35.8 °C. Monthly means: the coldest month's mean nightly low -2.8 °C in January (across the grid cells of the range -8.2 °C to 7.0 °C), the warmest month's mean daily high 29.6 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -13.9 °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: 56 to 60% 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 -24 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 Sisyrinchium angustifolium through the yearWarmest month July, mean daily high 30 °C; coldest month January, mean nightly low -2.8 °C; 1,188 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°-20°0°20°40°frost35.8° 99th-percentile day, NASA POWER-26.2° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200mm rainDLI 13–40RH 56–60%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 1025 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 °C5 / -1–168 / 1–1812 / 6–2219 / 13–2523 / 18–2928 / 23–3130 / 25–3229 / 25–3225 / 21–3019 / 14–2613 / 8–217 / 2–17
Night °C-3 / -8–7-2 / -7–92 / -3–118 / 3–1513 / 9–2018 / 14–2321 / 17–2420 / 16–2416 / 12–2210 / 6–175 / 1–12-1 / -5–8
Rain mm84 / 54–12279 / 56–129101 / 69–13298 / 71–121110 / 88–142112 / 98–163117 / 94–164103 / 80–168103 / 84–14594 / 75–12393 / 66–12194 / 61–131
DLI15 / 11–1920 / 18–2427 / 25–3134 / 32–3837 / 36–4040 / 38–4139 / 37–4134 / 33–3829 / 26–3222 / 19–2615 / 12–2113 / 9–18
RH %58 / 56–6257 / 55–6156 / 55–5956 / 55–5858 / 56–6059 / 57–6259 / 57–6360 / 57–6359 / 57–6358 / 56–6158 / 57–6159 / 57–62
How this section is made
Each figure is the median across the 1025 grid cells on land that hold in-range records (1148 records in those cells; 6 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 1038:1887 (38.075, -85.625). Over 44 years there: absolute minimum -26.2 °C, 1st-percentile night -13.9 °C, 99th-percentile day 35.8 °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 1025 distinct grid cells holding 1148 of the 1155 in-range records (6 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 1038:1887 (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 38.00_-85.625, lapse-corrected -24 m at 6.5 °C/km. Elevation: ETOPO 2022, 179 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.
NativeLabrador, Newfoundland, Nova Scotia, Ontario, Québec, Colorado, Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, Wisconsin, Connecticut, Indiana, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode I., Vermont, West Virginia, Texas, Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, District of Columbia · introduced: Ireland, France, Spain, Albania, Bulgaria, Yugoslavia, Turkey, Japan, Korea · 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 marker39.151, -76.777 · in the densest population, 431 records (27% of those in range)
Kew's description“perennial” · “subtropical” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1608 georeferenced records inside the native range; the climate across the range on the 1148 of them in the land cells it reads, of 1155 placed to within 10 km; the map shows only the 754 openly licensed ones, which alone would put the marker 41 km away. 226 records outside the WCVP native range not used. 453 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 1608 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Sisyrinchium angustifolium, photograph 1did not loadSisyrinchium angustifolium, photograph 2did not loadSisyrinchium angustifolium, photograph 3did not loadSisyrinchium angustifolium, photograph 4did not loadSisyrinchium angustifolium, photograph 5did not loadSisyrinchium angustifolium, photograph 6did not load

Photographs: (c) Matt Pelikan, some rights reserved (CC BY) (4); (c) Josiah Londerée, 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.

Cornus florida Cornus florida Flowering dogwood Photo: CC0, author not statedDesmodium paniculatum Desmodium paniculatum Narrow-leaf tick-trefoil Photo: CC BY, 岸本年郎Boehmeria cylindrica Boehmeria cylindrica Small-spike false nettle Photo: CC0, author not statedBetula nigra Betula nigra River birch Photo: CC0, author not statedPlatanus occidentalis Platanus occidentalis American sycamore Photo: CC BY, Michael A. ThaibinhAsimina triloba Asimina triloba Pawpaw Photo: CC0, author not stated

Other Sisyrinchium 25 in the reference

Sisyrinchium albidum Sisyrinchium albidum White blue-eyed grass Photo: CC0, author not statedSisyrinchium arenarium Sisyrinchium arenarium Iridaceae Photo: CC BY-SA, Grzegorz GrzejszczakSisyrinchium atlanticum Sisyrinchium atlanticum Eastern blue-eyed grass Photo: CC0, author not statedSisyrinchium bellum Sisyrinchium bellum Western blue-eyed grass Photo: CC BY-SA, paulexcoffSisyrinchium bermudiana Sisyrinchium bermudiana Blue-eyed-grass Photo: CC0, author not statedSisyrinchium californicum Sisyrinchium californicum Yellow-eyed-grass Photo: CC BY, Alexis Tinker-TsavalasSisyrinchium campestre Sisyrinchium campestre Prairie blue-eyed grass Photo: CC BY, Bria Abeles-AllisonSisyrinchium chilense Sisyrinchium chilense Swordleaf blue-eyed grass Photo: CC BY, Lucas CarboneSisyrinchium convolutum Sisyrinchium convolutum Iridaceae Photo: CC BY, Anders HastingsSisyrinchium demissum Sisyrinchium demissum Stiff blue-eyed grass Photo: CC BY, Abraham Sánchez RomeroSisyrinchium ensigerum Sisyrinchium ensigerum Swordleaf blue-eyed grass Photo: CC BY, IDClaireSisyrinchium graminifolium Sisyrinchium graminifolium Iridaceae Photo: CC BY, Gaston Carvallo B. all 26 ›

Names & registers

Also known as Bermudiana angustifolia; Bermudiana bermudiana f. graminoides; Bermudiana bermudiana var. albida; Bermudiana bermudiana var. angustifolia; Bermudiana bermudiana var. iridioides and 26 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Iridaceae
Described by
Mill.
Native to
Labrador, Newfoundland, Nova Scotia +39
Wild records
1608 in range · 754 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; 50 records within 1 km of a botanic garden, herbarium or zoo left out (37 at a botanic garden or arboretum, 7 at a herbarium, 6 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 38.00_-85.625, lapse-corrected -24 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 199 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…