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Eryngium yuccifolium; photograph (c) carter, some rights reserved (CC BY) CC BY(c) carter, some rights reserved (CC BY) · observed growing wild · 2026-09-19

Eryngium yuccifolium Michx.

Button eryngo; Button snakeroot; Rattlesnake-master

Apiaceae · Illinois, Iowa +22

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Eryngium yuccifolium, photograph author not stated, no rights reservedEryngium yuccifolium, photograph (c) carter, some rights reserved (CC BY)Eryngium yuccifolium, photograph (c) carter, some rights reserved (CC BY)Eryngium yuccifolium, photograph (c) Michael, Antoni and Nihat Hinczewski, some rights reserved (CC BY)Eryngium yuccifolium, photograph (c) Bria Abeles-Allison, some rights reserved (CC BY)Eryngium yuccifolium, photograph (c) carter, some rights reserved (CC BY) 89 photographs ›
Habitat figures
Cold floor (1 night in 100)
-15.7°C
Record low -28.0 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
30°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,102mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
12–41DLI
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

Eryngium yuccifolium, known as rattlesnake master, button eryngo, and button snake-root, is a perennial herb of the parsley family native to the tallgrass prairies of central and eastern North America. It grows from Minnesota east to Ohio and south to Texas and Florida, including a few spots in Connecticut, New Jersey, Maryland, and Delaware. There are two varieties found in the wild, the northern rattlesnake master (Eryngium yuccifolium var. yuccifolium) and the southern rattlesnake master (Eryngium yuccifolium var. synchaetum).

Quoted from Wikipedia, "Eryngium yuccifolium", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (812 mm of 1,092 mm) takes 8 months, March to October. Mean temperature moves 25.8 °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

1,092 mm in the median year at the habitat, 812 mm of it March to October. Wettest month June at 119 mm, driest months (2 at 62 mm). Across the grid cells of the range the year's total runs 901 mm to 1,493 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,102 mm, is the year's rain at the top of the page; the 1,092 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: 12 to 41 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 10, the highest 90th-percentile month 42).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -15.7 °C, the absolute minimum -28.0 °C, 4,608 frost nights in 44 years, 104.7 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 38.1 °C. Monthly means: the coldest month's mean nightly low -3.9 °C in January (across the grid cells of the range -10.8 °C to 7.2 °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: -15.7 °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 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 -25 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 Eryngium yuccifolium through the yearWarmest months July and August, mean daily high 30 °C; coldest month January, mean nightly low -3.9 °C; 1,092 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°frost38.1° 99th-percentile day, NASA POWER-28.0° lowest night in 44 years, NASA POWER°C · day and nightcold quarter050100150200mm rainDLI 12–41RH 55–60%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 1050 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 / -2–168 / 0–1813 / 6–2119 / 14–2524 / 20–2928 / 25–3230 / 28–3330 / 26–3326 / 22–3019 / 15–2613 / 7–216 / -1–17
Night °C-4 / -11–7-2 / -8–93 / -3–128 / 4–1514 / 10–2019 / 15–2321 / 18–2421 / 17–2416 / 13–2210 / 7–174 / 0–12-2 / -8–9
Rain mm62 / 26–12662 / 32–13384 / 51–13295 / 77–122116 / 90–146119 / 103–170112 / 94–165107 / 78–16193 / 79–13686 / 69–12584 / 53–12272 / 38–133
DLI15 / 12–1920 / 18–2327 / 26–3034 / 32–3737 / 37–4041 / 39–4140 / 38–4236 / 34–3830 / 27–3222 / 19–2715 / 12–2112 / 10–17
RH %59 / 58–6459 / 57–6157 / 55–5955 / 54–5857 / 55–6058 / 56–6258 / 57–6359 / 57–6358 / 56–6157 / 56–5959 / 57–6060 / 58–63
How this section is made
Each figure is the median across the 1050 grid cells on land that hold in-range records (1464 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 1027:1793 (38.625, -90.325). Over 44 years there: absolute minimum -28.0 °C, 1st-percentile night -15.7 °C, 99th-percentile day 38.1 °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 1050 distinct grid cells holding 1464 of the 1465 in-range records (1 further cell with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 1027:1793 (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 38.50_-90.625, lapse-corrected -25 m at 6.5 °C/km. Elevation: ETOPO 2022, 157 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.
NativeIllinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, Wisconsin, Indiana, Michigan, Ohio, Texas, Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia · introduced: Connecticut · 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 marker42.197, -88.328 · in the densest population, 397 records (23% of those in range)
Extinct inNew Jersey · recorded as extinct by WCVP: history, not habitat; no records are tested against these regions
Kew's description“perennial” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 1701 georeferenced records inside the native range; the climate across the range on the 1464 of them in the land cells it reads, of 1465 placed to within 10 km; the map shows only the 313 openly licensed ones, which alone would put the marker 71 km away. 28 records outside the WCVP native range not used. 236 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 1701 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Eryngium yuccifolium, photograph 1did not loadEryngium yuccifolium, photograph 2did not loadEryngium yuccifolium, photograph 3did not loadEryngium yuccifolium, photograph 4did not loadEryngium yuccifolium, photograph 5did not loadEryngium yuccifolium, photograph 6did not load

Photographs: author not stated, no rights reserved · CC0; (c) carter, some rights reserved (CC BY) (3); (c) Michael, Antoni and Nihat Hinczewski, some rights reserved (CC BY); (c) Bria Abeles-Allison, some rights reserved (CC BY).

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

Baptisia australis Baptisia australis Blue wild indigo Photo: CC BY, Andrew ConboyScutellaria parvula Scutellaria parvula Small skullcap Photo: CC BY, Patrick JacksonElymus macgregorii Elymus macgregorii Early wildrye Photo: CC BY, Bryan ConnollySisyrinchium albidum Sisyrinchium albidum White blue-eyed grass Photo: CC0, author not statedAmbrosia trifida Ambrosia trifida Giant ragweed Photo: CC BY, Michael A. ThaibinhGleditsia triacanthos Gleditsia triacanthos Honey locust Photo: CC BY, Lisa Bennett

Other Eryngium 46 in the reference

Eryngium agavifolium Eryngium agavifolium Agave-leaved sea holly Photo: CC BY, Lucas CarboneEryngium alpinum Eryngium alpinum Alpine Sea Holly Photo: CC BY, Katrin SimonEryngium amethystinum Eryngium amethystinum Italian Eryngo Photo: CC0, author not statedEryngium aquaticum Eryngium aquaticum Rattlesnake-master Photo: CC0, author not statedEryngium aristulatum Eryngium aristulatum California eryngo Photo: CC BY, jayjt Eryngium billardierei Apiaceae Eryngium bourgatii Eryngium bourgatii Amethyst Eryngo Photo: CC BY-SA, Benoit NABHOLZEryngium caeruleum Eryngium caeruleum Apiaceae Photo: CC0, author not statedEryngium campestre Eryngium campestre Field eryngo Photo: CC BY, Jan ProkešEryngium carlinae Eryngium carlinae Toad's Herb Photo: CC BY, Eduardo CordobaEryngium corniculatum Eryngium corniculatum One-horned eryngium Photo: CC BY, Duarte FradeEryngium coronatum Eryngium coronatum Apiaceae Photo: CC BY, Nico Yak all 47 ›

Names & registers

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Apiaceae
Described by
Michx.
Native to
Illinois, Iowa, Kansas +21
Wild records
1701 in range · 313 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; 93 records within 1 km of a botanic garden, herbarium or zoo left out (79 at a botanic garden or arboretum, 2 at a herbarium, 12 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 38.50_-90.625, lapse-corrected -25 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 56 datasets via GBIF.org; each carries its own licence.

Cultifolio

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