Example ⟳ +
An example collection, so you can see what this page does. Nothing added here is kept: leaving deletes it.
Lactuca biennis; photograph (c) Henry "Nick" Robertson, some rights reserved (CC BY-SA) CC BY-SA(c) Henry "Nick" Robertson, some rights reserved (CC BY-SA) · observed growing wild · 2026-09-17

Lactuca biennis (Moench) Fernald

Tall blue lettuce; Blue wood lettuce; Biennial lettuce; Wild blue lettuce

Asteraceae · Alaska, Yukon +46

Add one to my plants
Sow seed
Lactuca biennis, photograph (c) Robert Stegmann, some rights reserved (CC BY)Lactuca biennis, photograph (c) Dustin Snider, some rights reserved (CC BY)Lactuca biennis, photograph (c) Dustin Snider, some rights reserved (CC BY)Lactuca biennis, photograph (c) Chris O'Donoghue, some rights reserved (CC BY)Lactuca biennis, photograph (c) Chris O'Donoghue, some rights reserved (CC BY)Lactuca biennis, photograph (c) Chris O'Donoghue, some rights reserved (CC BY) 84 photographs ›
Habitat figures
Cold floor (1 night in 100)
-11.9°C
Record low -22.2 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
26°C
Jul at the habitat CHELSA
Rain a year (median across the range)
1,138mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
9–39DLI
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

Lactuca biennis is a North American species of wild lettuce known by the common names tall blue lettuce and blue wood lettuce. It is widespread across much of the United States and Canada from Alaska and Yukon south as far as California, New Mexico, and Georgia.

Quoted from Wikipedia, "Lactuca biennis", CC BY-SA 4.0.

About the genus · Lactuca

Lactuca, commonly known as lettuce, is a genus of flowering plants in the family Asteraceae. The genus includes at 117 recognized species, distributed worldwide, but mainly in temperate Eurasia.

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

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (808 mm of 1,136 mm) takes 8 months, April to November. Mean temperature moves 26.3 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: October to May.

Rain

1,136 mm in the median year at the habitat, 808 mm of it April to November. Wettest month June at 109 mm, driest month February at 73 mm. Across the grid cells of the range the year's total runs 843 mm to 1,410 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,138 mm, is the year's rain at the top of the page; the 1,136 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: 9 to 39 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 7, 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 -11.9 °C, the absolute minimum -22.2 °C, 4,629 frost nights in 44 years, 105.2 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 22.9 °C. Monthly means: the coldest month's mean nightly low -9.0 °C in January (across the grid cells of the range -15.1 °C to -3.7 °C), the warmest month's mean daily high 25.9 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -11.9 °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 62% 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 +74 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 Lactuca biennis through the yearWarmest month July, mean daily high 26 °C; coldest month January, mean nightly low -9.0 °C; 1,136 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.-30°-20°-10°0°10°20°30°frost22.9° 99th-percentile day, NASA POWER-22.2° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0255075100125150mm rainDLI 9–39RH 56–62%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 1274 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-1 / -7–41 / -5–66 / 1–1013 / 7–1719 / 14–2224 / 19–2626 / 22–2925 / 22–2821 / 18–2414 / 11–178 / 3–111 / -4–6
Night °C-9 / -15–-4-8 / -13–-3-4 / -8–13 / -1–68 / 5–1114 / 11–1717 / 14–1917 / 14–1913 / 10–157 / 3–91 / -3–4-5 / -11–-1
Rain mm79 / 31–10473 / 29–9985 / 46–11794 / 67–118102 / 79–122109 / 86–130108 / 81–131100 / 80–124101 / 83–12199 / 70–13195 / 57–12991 / 39–123
DLI12 / 10–1418 / 16–2025 / 24–2632 / 30–3336 / 35–3839 / 37–4138 / 37–4133 / 32–3526 / 24–2818 / 15–2112 / 9–149 / 7–12
RH %62 / 57–6660 / 56–6457 / 55–6156 / 55–5857 / 55–6059 / 57–6159 / 57–6260 / 58–6260 / 58–6260 / 57–6260 / 58–6462 / 57–67
How this section is made
Each figure is the median across the 1274 grid cells holding the 1422 in-range records, 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 904:1879 (44.775, -86.025). Over 44 years there: absolute minimum -22.2 °C, 1st-percentile night -11.9 °C, 99th-percentile day 22.9 °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 1274 distinct grid cells holding 1422 of the 1422 in-range records; extremes and elevation at the typical cell 904:1879 (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 45.00_-86.250, lapse-corrected +74 m at 6.5 °C/km. Elevation: ETOPO 2022, 254 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, Yukon, Alberta, British Columbia, Manitoba, Saskatchewan, Labrador, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward I., Québec, Colorado, Idaho, Montana, Oregon, Washington, Wyoming, Illinois, Iowa, Minnesota, North Dakota, South Dakota, Wisconsin, Connecticut, Indiana, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode I., Vermont, West Virginia, California, Utah, New Mexico, Delaware, Kentucky, Maryland, North Carolina, Tennessee, Virginia, District of Columbia · 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 marker43.474, -72.663 · in the densest population, 945 records (53% of those in range)
Kew's description“temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1788 georeferenced records inside the native range; the climate across the range on the 1422 of them placed to within 10 km; the map shows only the 678 openly licensed ones, which alone would put the marker 26 km away. 23 records outside the WCVP native range not used. 366 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 4° block of the 1788 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Lactuca biennis, photograph 1did not loadLactuca biennis, photograph 2did not loadLactuca biennis, photograph 3did not loadLactuca biennis, photograph 4did not loadLactuca biennis, photograph 5did not loadLactuca biennis, photograph 6did not load

Photographs: (c) Robert Stegmann, some rights reserved (CC BY); (c) Dustin Snider, some rights reserved (CC BY) (2); (c) Chris O'Donoghue, some rights reserved (CC BY) (3).

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

Hieracium scabrum Hieracium scabrum Rough hawkweed Photo: CC BY, Sam TurnerAmelanchier laevis Amelanchier laevis Allegheny serviceberry Photo: CC BY, Blake RossPolygonatum pubescens Polygonatum pubescens Hairy Solomon's-seal Photo: CC BY, Tom ScavoAronia melanocarpa Aronia melanocarpa Black chokeberry Photo: CC BY, Lythronax246Chelone glabra Chelone glabra White turtlehead Photo: CC0, author not statedCarex communis Carex communis Fibrous-root sedge Photo: CC0, author not stated

Other Lactuca 16 in the reference

Lactuca canadensis Lactuca canadensis Canada lettuce Photo: CC0, author not statedLactuca floridana Lactuca floridana Woodland lettuce Photo: CC0, author not statedLactuca graminifolia Lactuca graminifolia Grass-leaf lettuce Photo: CC BY, Athena PhilipsLactuca hirsuta Lactuca hirsuta Hairy lettuce Photo: CC BY, Quinten WiegersmaLactuca indica Lactuca indica Indian lettuce Photo: CC0, author not statedLactuca muralis Lactuca muralis Asteraceae Photo: CC BY-SA, Anneli SaloLactuca perennis Lactuca perennis Mountain lettuce Photo: CC BY-SA, Emanuele SantarelliLactuca plumieri Lactuca plumieri Hairless blue-sow-thistle Photo: CC BY-SA, Luc AudrainLactuca quercina Lactuca quercina Wild lettuce Photo: CC BY, Илья РуденкоLactuca saligna Lactuca saligna Least lettuce Photo: CC BY, Duarte FradeLactuca sativa Lactuca sativa Garden lettuce Photo: CC0, author not statedLactuca serriola Lactuca serriola Prickly lettuce Photo: CC BY, Анна Митрошенкова all 17 ›

Names & registers

Also known as Agathyrsus floridanus; Cicerbita canadensis var. integrifolia; Cicerbita spicata; Cicerbita spicata var. integrifolia; Cicerbita spicata var. spicata and 21 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Asteraceae
Described by
(Moench) Fernald
Native to
Alaska, Yukon, Alberta +45
Wild records
1788 in range · 678 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; 33 records within 1 km of a botanic garden, herbarium or zoo left out (26 at a botanic garden or arboretum, 1 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 45.00_-86.250, lapse-corrected +74 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 89 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…