Example ⟳ +
An example collection, so you can see what this page does. Nothing added here is kept: leaving deletes it.
Cryptogramma acrostichoides; photograph (c) Stevie Steele, some rights reserved (CC BY) CC BY(c) Stevie Steele, some rights reserved (CC BY) · observed growing wild · 2026-09-20

Cryptogramma acrostichoides R.Br.

American parsley fern; American rock-brake; Mountain parsley fern; Parsley rockbrake

Pteridaceae · Kamchatka, Magadan +21

Cited as Kew's World Checklist cites it, Cryptogramma acrostichoides R.Br.: GBIF's backbone key for this page carries the name with another author, R.Br. ex Richards.

Add one to my plants
Sow seed
Cryptogramma acrostichoides, photograph (c) Stevie Steele, some rights reserved (CC BY)Cryptogramma acrostichoides, photograph (c) Stevie Steele, some rights reserved (CC BY)Cryptogramma acrostichoides, photograph (c) Alexis Tinker-Tsavalas, some rights reserved (CC BY)Cryptogramma acrostichoides, photograph author not stated, no rights reservedCryptogramma acrostichoides, photograph author not stated, no rights reservedCryptogramma acrostichoides, photograph author not stated, no rights reserved 82 photographs ›
Habitat figures
Cold floor (1 night in 100)
-14.7°C
Record low -28.0 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
21°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
1,528mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
7–43DLI
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 October to April, with nights below freezing; no growing season read. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

Summary

Cryptogramma acrostichoides is a fern species in the Cryptogrammoideae subfamily of the Pteridaceae. It is known by the common names American parsley fern and American rockbrake and is native to most of western North America, where it grows in the cracks of rocks in many types of sunny mountainous habitat.

Quoted from Wikipedia, "Cryptogramma acrostichoides", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a rainy season and no growing season: 70% of the median year's rain (1,196 mm of 1,565 mm) falls in October to April, the cooler part of the year, but the mean nightly low is below freezing in February, March, April, May, December and January, so the rule reads no growing season from it. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: April to October.

Rain

1,565 mm in the median year at the habitat, 1,196 mm of it October to April. Wettest month January at 220 mm, driest month July at 55 mm. Across the grid cells of the range the year's total runs 773 mm to 3,112 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,528 mm, is the year's rain at the top of the page; the 1,565 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: 7 to 43 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 52).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -14.7 °C, the absolute minimum -28.0 °C, 7,511 frost nights in 44 years, 170.7 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 34.2 °C. Monthly means: the coldest month's mean nightly low -7.8 °C in December (across the grid cells of the range -16.6 °C to 0.1 °C), the warmest month's mean daily high 20.9 °C in July and August (median year across the grid cells of the range, CHELSA). Cold floor: -14.7 °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 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 -39 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 Cryptogramma acrostichoides through the yearWarmest months July and August, mean daily high 21 °C; coldest month December, mean nightly low -7.8 °C; 1,565 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°frost34.2° 99th-percentile day, NASA POWER-28.0° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400500mm rainDLI 7–43RH 55–65%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 961 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 / -7–51 / -6–74 / -2–97 / 2–1212 / 7–1717 / 13–2121 / 16–2521 / 16–2517 / 12–2110 / 4–143 / -3–8-1 / -8–5
Night °C-7 / -16–0-7 / -15–1-5 / -12–2-3 / -9–41 / -4–75 / 1–119 / 5–149 / 5–146 / 1–111 / -5–7-4 / -12–3-8 / -17–0
Rain mm220 / 54–444161 / 46–314147 / 54–295107 / 55–21993 / 51–16185 / 33–14555 / 18–10856 / 20–11780 / 36–151131 / 60–342211 / 60–482219 / 60–445
DLI8 / 5–1814 / 11–2523 / 18–3433 / 28–4339 / 34–4941 / 36–5243 / 37–5238 / 31–4728 / 22–3817 / 12–289 / 6–207 / 4–16
RH %65 / 54–6962 / 56–6661 / 55–6559 / 54–6459 / 51–6358 / 46–6356 / 44–6155 / 44–6156 / 46–6361 / 50–6665 / 53–6965 / 55–70
How this section is made
Each figure is the median across the 961 grid cells on land that hold in-range records (1515 records in those cells; 2 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 920:1200 (43.975, -119.975). Over 44 years there: absolute minimum -28.0 °C, 1st-percentile night -14.7 °C, 99th-percentile day 34.2 °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 961 distinct grid cells holding 1515 of the 1517 in-range records (2 further cells with records at sea, by the elevation layer, left out); extremes and elevation at the typical cell 920:1200 (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 44.00_-120.000, lapse-corrected -39 m at 6.5 °C/km. Elevation: ETOPO 2022, 1402 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.
NativeKamchatka, Magadan, Alaska, Northwest Territories, Yukon, Alberta, British Columbia, Manitoba, Saskatchewan, Ontario, Colorado, Idaho, Montana, Oregon, Washington, Wyoming, South Dakota, Michigan, Arizona, California, Nevada, Utah, New Mexico · 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 marker49.39, -123.332 · in the densest population, 769 records (43% 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 1798 georeferenced records inside the native range; the climate across the range on the 1515 of them in the land cells it reads, of 1517 placed to within 10 km; the map shows only the 780 openly licensed ones, which alone would put the marker 28 km away. 2 records outside the WCVP native range not used. 281 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 1798 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Cryptogramma acrostichoides, photograph 1did not loadCryptogramma acrostichoides, photograph 2did not loadCryptogramma acrostichoides, photograph 3did not loadCryptogramma acrostichoides, photograph 4did not loadCryptogramma acrostichoides, photograph 5did not loadCryptogramma acrostichoides, photograph 6did not load

Photographs: (c) Stevie Steele, some rights reserved (CC BY) (2); (c) Alexis Tinker-Tsavalas, some rights reserved (CC BY); author not stated, no rights reserved · CC0 (3).

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

Primula jeffreyi Primula jeffreyi Primulaceae Photo: CC BY, Walter SiegmundLewisia columbiana Lewisia columbiana Columbia lewisia Photo: CC0, author not statedVaccinium membranaceum Vaccinium membranaceum Montana huckleberry Photo: CC BY, Jake AndersonBrewerimitella breweri Brewerimitella breweri Brewer's mitrewort Photo: CC0, author not statedTsuga mertensiana Tsuga mertensiana Mountain hemlock Photo: CC0, author not statedDelphinium glareosum Delphinium glareosum Rockslide larkspur Photo: CC BY, John A Haskins

Other Cryptogramma 3 in the reference

Cryptogramma crispa Cryptogramma crispa Parsley fern Photo: CC0, author not statedCryptogramma fumariifolia Cryptogramma fumariifolia Pteridaceae Photo: CC BY, Matt BergerCryptogramma stelleri Cryptogramma stelleri Fragile rockbrake Photo: CC BY, crothfels

Names & registers

Also known as Allosorus acrostichoides; Allosorus crispus var. acrostichoides; Allosorus foveolatus; Cryptogramma crispa subsp. acrostichoides; Cryptogramma crispa var. acrostichoides and 3 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Pteridaceae
Described by
R.Br.
Native to
Kamchatka, Magadan, Alaska +20
Wild records
1798 in range · 780 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 2026-10-22GBIF's key 5275452 is Cryptogramma acrostichoides R.Br. ex Richards.; the page links Kew's Cryptogramma acrostichoides R.Br., and the name is cited as Kew cites it
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; 1 record within 1 km of a botanic garden, herbarium or zoo left out (1 at a botanic garden or arboretum; 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 44.00_-120.000, lapse-corrected -39 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 98 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…