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Allium amplectens; photograph (c) Arvel Hernandez, some rights reserved (CC BY) CC BY(c) Arvel Hernandez, some rights reserved (CC BY) · observed growing wild · 2026-06-29

Allium amplectens Torr.

Slim-leaved onion; Narrow-leaved onion; Narrowleaf onion

Amaryllidaceae · British Columbia, Oregon +2 · listed by its family as a bulb, tuber or caudex

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Allium amplectens, photograph (c) Parker James Lloyd, some rights reserved (CC BY)Allium amplectens, photograph (c) Parker James Lloyd, some rights reserved (CC BY)Allium amplectens, photograph (c) Arvel Hernandez, some rights reserved (CC BY)Allium amplectens, photograph (c) Arvel Hernandez, some rights reserved (CC BY)Allium amplectens, photograph (c) Arvel Hernandez, some rights reserved (CC BY)Allium amplectens, photograph (c) Arvel Hernandez, some rights reserved (CC BY) 75 photographs ›
Habitat figures
Cold floor (1 night in 100)
-5.1°C
Record low -11.5 °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)
1,187mm
8 months of 25 mm or more in the median year CHELSA
Open-sky light
11–52DLI
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 November 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

Allium amplectens, the narrowleaf onion, is a species of flowering plant. It is an onion native to the west coast of the United States, in Oregon, Washington State and California, also British Columbia in Canada. It grows in woods and especially in clay and serpentine soils.

Quoted from Wikipedia, "Allium amplectens", CC BY-SA 4.0.

About the genus · Allium

Allium is a large genus of monocotyledonous flowering plants with 1112 accepted species, making Allium the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, and some have a long history of cultivation and human consumption such as the onion, garlic, scallions, shallots, leeks, and chives.

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

Cultivation

Grouped as a bulb, tuber or caudex, listed under the family Amaryllidaceae in the archetype table, and Kew describes it as “bulbous geophyte”.

Seasons

The rain rule reads a winter growing season: 70% of the median year's rain (889 mm of 1,144 mm) falls in November to March, cooler than the year (wet-season mean 6.6 °C against a yearly mean of 12.4 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: May to September.

Rain

1,144 mm in the median year at the habitat, 889 mm of it November to March. Wettest month December at 219 mm, driest month July at 5 mm. Across the grid cells of the range the year's total runs 608 mm to 1,839 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,187 mm, is the year's rain at the top of the page; the 1,144 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: 11 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 6, the highest 90th-percentile month 53).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -5.1 °C, the absolute minimum -11.5 °C, 1,917 frost nights in 44 years, 43.6 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 38.7 °C. Monthly means: the coldest month's mean nightly low 1.8 °C in December (across the grid cells of the range -3.1 °C to 4.7 °C), the warmest month's mean daily high 30.1 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -5.1 °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: 48 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 +448 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.

Group. Listed under the family Amaryllidaceae in the archetype table, and Kew describes it as “bulbous geophyte”. A group is taken only where Kew's description of the species agrees with the table's listing. The table gives no figure and no prose; the cold floor is the habitat's alone.

Climate across the habitat

Habitat months, northern hemisphere

Habitat climate of Allium amplectens through the yearWarmest month July, mean daily high 30 °C; coldest month December, mean nightly low 1.8 °C; 1,144 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°40°frost38.7° 99th-percentile day, NASA POWER-11.5° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400mm rainDLI 11–52RH 48–61%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 439 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 °C10 / 6–1412 / 7–1514 / 9–1817 / 12–2221 / 16–2725 / 19–3230 / 23–3629 / 23–3527 / 20–3220 / 14–2513 / 8–189 / 5–13
Night °C2 / -3–52 / -3–64 / -1–75 / 1–99 / 5–1312 / 8–1714 / 12–1914 / 11–1912 / 9–169 / 5–125 / 0–82 / -3–5
Rain mm201 / 104–300165 / 94–249141 / 77–22480 / 44–13251 / 25–8424 / 5–545 / 0–207 / 2–2520 / 7–4968 / 35–131163 / 76–279219 / 111–350
DLI13 / 8–1519 / 13–2128 / 21–3038 / 29–4045 / 36–4751 / 40–5252 / 43–5347 / 38–4837 / 29–3926 / 17–2815 / 9–1811 / 6–14
RH %61 / 56–6760 / 57–6559 / 55–6456 / 51–6254 / 48–6151 / 44–5948 / 40–5849 / 41–5949 / 43–5952 / 47–6359 / 54–6760 / 56–68
How this section is made
Each figure is the median across the 439 grid cells on land that hold in-range records (845 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 1015:1178 (39.225, -121.075). Over 44 years there: absolute minimum -11.5 °C, 1st-percentile night -5.1 °C, 99th-percentile day 38.7 °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 439 distinct grid cells holding 845 of the 849 in-range records (3 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 1015:1178 (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 39.00_-121.250, lapse-corrected +448 m at 6.5 °C/km. Elevation: ETOPO 2022, 752 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.
NativeBritish Columbia, Oregon, Washington, California · 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 marker39.729, -121.706 · in the densest population, 636 records (47% of those in range)
Kew's description“bulbous geophyte” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1344 georeferenced records inside the native range; the climate across the range on the 845 of them in the land cells it reads, of 849 placed to within 10 km; the map shows only the 588 openly licensed ones, which alone would put the marker 53 km away. 495 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 1344 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Allium amplectens, photograph 1did not loadAllium amplectens, photograph 2did not loadAllium amplectens, photograph 3did not loadAllium amplectens, photograph 4did not loadAllium amplectens, photograph 5did not loadAllium amplectens, photograph 6did not load

Photographs: (c) Parker James Lloyd, some rights reserved (CC BY) (2); (c) Arvel Hernandez, some rights reserved (CC BY) (4).

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

Carex nudata Carex nudata Naked sedge Photo: CC BY, Elly Poretsky Convolvulus occidentalis Convolvulaceae Calochortus uniflorus Calochortus uniflorus Monterey mariposa lily Photo: CC BY, wildflowerwatchingDichelostemma × venustum Dichelostemma × venustum Asparagaceae Photo: CC BY, Kyle ElshoffDichelostemma congestum Dichelostemma congestum Ookow Photo: CC BY, Parker James LloydErythronium californicum Erythronium californicum California fawn-lily Photo: CC BY, gretchenparadis

Other Allium 241 in the reference

Allium acuminatum Allium acuminatum Tapertip onion Photo: CC BY-SA, Brian FinzelAllium acutiflorum Allium acutiflorum Amaryllidaceae Photo: CC BY, Nicola CrockfordAllium aflatunense Allium aflatunense Amaryllidaceae Photo: CC0, author not statedAllium akaka Allium akaka Amaryllidaceae Photo: CC BY-SA, C T Johansson Allium alexeianum Amaryllidaceae Allium altaicum Allium altaicum Altai onion Photo: CC BY, Urgamal MagsarAllium altissimum Allium altissimum Amaryllidaceae Photo: CC BY, Wolfgang AhlmerAllium altyncolicum Allium altyncolicum Altynkol Chive Photo: CC BY, Oleg KosterinAllium amethystinum Allium amethystinum Amethyst Garlic Photo: CC BY, Eleftherios KatsillisAllium ampeloprasum Allium ampeloprasum Wild Leek Photo: CC BY, Felix Blesch Allium amphibolum Amaryllidaceae Allium angulosum Allium angulosum Mouse garlic Photo: CC BY, Christoph Moning all 242 ›

Names & registers

Also known as Allium acuminatum var. gracile; Allium attenuatum; Allium attenuifolium; Allium attenuifolium var. monospermum; Allium monospermum and 3 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Amaryllidaceae
Described by
Torr.
Native to
British Columbia, Oregon, Washington +1
Wild records
1344 in range · 588 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 2026-10-21
GBIF species record gbif.species answeredasked 2026-10-21
GBIF synonyms gbif.synonyms answeredasked 2026-10-21
GBIF common names gbif.vernacular answeredasked 2026-10-21names fetched 2026-10-21
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; 36 records within 1 km of a botanic garden, herbarium or zoo left out (34 at a botanic garden or arboretum, 2 at a zoo; Wikidata's list)
Habitat climate climate answeredasked 2026-10-21
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-21NASA POWER (MERRA-2) daily 1981–2024, cell 39.00_-121.250, lapse-corrected +448 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-21
Wikipedia wikipedia answeredasked 2026-10-21
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 2026-10-21
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 54 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…