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Marsilea villosa; photograph (c) Kevin Faccenda, some rights reserved (CC BY) CC BY(c) Kevin Faccenda, some rights reserved (CC BY) · observed growing wild · 2021-12-15

Marsilea villosa Kaulf.

'Ihi'ihi; Villous waterclover

Marsileaceae · Hawaii

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Marsilea villosa, photograph (c) Kevin Faccenda, some rights reserved (CC BY)Marsilea villosa, photograph (c) Kevin Faccenda, some rights reserved (CC BY)Marsilea villosa, photograph (c) Kevin Faccenda, some rights reserved (CC BY)Marsilea villosa, photograph (c) Kevin Faccenda, some rights reserved (CC BY)Marsilea villosa, photograph (c) Kevin Faccenda, some rights reserved (CC BY)Marsilea villosa, photograph (c) Kevin Faccenda, some rights reserved (CC BY) 12 photographs ›
Habitat figuresfrom few records
Coldest month, mean nightly low
19.7°C
Feb at the habitat, not a floor; extremes not used (sea cell) CHELSA
Warmest month, mean daily high
26°C
Jul, Aug, Sep and Oct at the habitat CHELSA
Rain a year (median across the range)
977mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
27–46DLI
Lowest to highest month (DLI) CHELSA
The year in the habitat's months, not shifted
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
A sharp rainy season, October to April (the habitat's months, not shifted), in a year of even temperature. rain rule, CHELSA
Not shifted: the shift rule does not apply to this habitat. The chart is in the habitat's months.

From few records: 6 records in 5 grid cells. The records.

Summary

Marsilea villosa, the ʻihiʻihi (Hawaiian) or villous waterclover (English), is a species of fern that is endemic to the islands of Oʻahu, Molokaʻi and Niʻihau in Hawaii. It is found exclusively in areas that experience periodic flooding and become ephemeral pools within low elevation dry forests and shrublands. Standing water allows the sporocarp to open and release spores. It also enables the resulting sperm to swim toward and fertilize female ova. More on Wikipedia ›

Quoted from Wikipedia, "Marsilea villosa", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a sharp season: 70% of the median year's rain (712 mm of 977 mm) falls in October to April. The temperature curve is flat, 3.8 °C between the warmest and coldest month, so the growing-season rule does not infer a growing season from it. Months are the habitat's, northern hemisphere. The temperature curve moves under 4 °C between the warmest and coldest month, where the shift rule does not apply, so they are not shifted for a collection elsewhere.

Rain

977 mm in the median year at the habitat, 712 mm of it October to April. Wettest month December at 134 mm, driest month June at 46 mm. Across the grid cells of the range the year's total runs 804 mm to 1,144 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 977 mm, is the year's rain at the top of the page; the 977 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: 27 to 46 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 27, the highest 90th-percentile month 47).

Warmth and air
Temperature

Monthly means: the coldest month's mean nightly low 19.7 °C in February (across the grid cells of the range 18.6 °C to 21.6 °C), the warmest month's mean daily high 26.2 °C in September (median year across the grid cells of the range, CHELSA). Cold floor: none read. The nearest figure is 19.7 °C, the coldest month's mean nightly low, February, in the median year (CHELSA); a month's mean of its nightly lows is warmer than the nights a floor is read from. The daily extremes were read at a weather cell that is mostly sea and are not used.

Humidity

Relative humidity at the habitat: 60 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. CHELSA monthly means, median year across the grid cells of the range. No cold floor is read without a daily extremes series; the coldest month's mean nightly low named in its sentence is not one. 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

From few records: this habitat climate is read from 6 records in 5 grid cells; a page says so under 12 records or 5 cells, and shows the figures as read.

Habitat months, northern hemisphere

Habitat climate of Marsilea villosa through the yearWarmest months July, August, September and October, mean daily high 26 °C; coldest month February, mean nightly low 19.7 °C; 977 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA. Habitat months, northern hemisphere.15°20°25°30°°C · day and nightcold quarter050100150200mm rainDLI 27–46RH 60–62%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 5 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C24 / 23–2423 / 22–2423 / 23–2424 / 23–2424 / 24–2625 / 25–2726 / 26–2726 / 26–2826 / 26–2826 / 26–2725 / 25–2624 / 23–24
Night °C20 / 19–2220 / 19–2220 / 19–2220 / 19–2221 / 20–2322 / 21–2423 / 22–2423 / 22–2523 / 22–2523 / 22–2522 / 21–2421 / 20–23
Rain mm112 / 108–13887 / 79–104112 / 104–13470 / 49–8155 / 34–6446 / 22–5158 / 30–6754 / 32–6352 / 33–5986 / 69–99111 / 110–129134 / 132–161
DLI29 / 28–2934 / 33–3439 / 38–3943 / 43–4346 / 45–4646 / 46–4746 / 45–4645 / 45–4542 / 42–4236 / 36–3730 / 29–3027 / 27–28
RH %61 / 60–6560 / 60–6460 / 60–6461 / 60–6461 / 60–6461 / 61–6562 / 61–6662 / 61–6662 / 61–6562 / 61–6562 / 61–6661 / 60–65

The daily extremes were read at a NASA POWER cell that is 48% land: neither it nor the next candidates whose coldest month's mean nightly low is within 2 °C of the median across cells sit in a POWER cell that is mostly land, and the rule reads a cold floor only from a cell that is mostly land, so none is read for this species. Nor is the coldest month's mean nightly low taken as one: it is a mean of a month's lows, not its coldest night. What that cell gave over 44 years: absolute minimum 16.7 °C, 1st-percentile night 18.8 °C, 99th-percentile day 28.8 °C.

How this section is made
Each figure is the median across the 5 grid cells holding the 6 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 1371:440 (21.425, -157.975). 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 5 distinct grid cells holding 6 of the 6 in-range records; extremes and elevation at the typical cell 1371:440 (its coldest month's mean nightly low nearest the median across cells, though its NASA POWER cell is only 48% land and none of the 4 next candidates within 2 °C of the median was mostly land); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 21.50_-158.125, lapse-corrected +54 m at 6.5 °C/km. Elevation: ETOPO 2022, 132 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.
NativeHawaii · 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 marker21.433, -157.967 · in the densest population, 37 records (97% of those in range)
Evidence usedThe map marker rests on all 38 georeferenced records inside the native range; the climate across the range on the 6 of them placed to within 10 km; the map shows only the 26 openly licensed ones, which alone would put the marker 9 km away. Under a dozen records behind the climate. 32 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 38 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Marsilea villosa, photograph 1did not loadMarsilea villosa, photograph 2did not loadMarsilea villosa, photograph 3did not loadMarsilea villosa, photograph 4did not loadMarsilea villosa, photograph 5did not loadMarsilea villosa, photograph 6did not load

Photographs: (c) Kevin Faccenda, some rights reserved (CC BY) (6).

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

Sida fallax Sida fallax Yellow `ilima Photo: CC0, author not statedErythrina sandwicensis Erythrina sandwicensis Hawaiian Coral Tree Photo: CC0, author not statedHibiscus arnottianus Hibiscus arnottianus White Molokai Hibiscus Photo: CC0, author not statedWikstroemia uva-ursi Wikstroemia uva-ursi Hillside false ohelo Photo: CC0, author not statedSapindus oahuensis Sapindus oahuensis Sapindaceae Photo: CC0, author not statedEragrostis variabilis Eragrostis variabilis Poaceae Photo: CC BY, Kevin Faccenda

Other Marsilea 12 in the reference

Marsilea ancylopoda Marsilea ancylopoda Tropical waterclover Photo: CC BY, Franco RichieriMarsilea batardae Marsilea batardae Lusitanian Water Clover Photo: CC BY, zebedeugalinhaMarsilea crenata Marsilea crenata Nardoo Photo: CC BY, Belinda ForbesMarsilea drummondii Marsilea drummondii Nardoo Photo: CC BY, Petra HollandMarsilea hirsuta Marsilea hirsuta Rough waterclover Photo: CC BY-SA, Greg TasneyMarsilea macropoda Marsilea macropoda Bigfoot waterclover Photo: CC BY, Chet BurrierMarsilea minuta Marsilea minuta Dwarf waterclover Photo: CC0, author not statedMarsilea mutica Marsilea mutica Australian water-clover Photo: CC BY, Reid HardinMarsilea quadrifolia Marsilea quadrifolia European water-clover Photo: CC BY, yajapinMarsilea schelpeana Marsilea schelpeana Cutleaf clover Photo: CC BY-SA, Andrew HankeyMarsilea strigosa Marsilea strigosa Marsileaceae Photo: CC BY, Santiago Martín-BravoMarsilea vestita Marsilea vestita Hairy water-clover Photo: CC BY, Sam Kieschnick

Names & registers

Also known as Zaluzianskia villosa; Zaluzianskya villosa. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Marsileaceae
Described by
Kaulf.
Native to
Hawaii
Wild records
38 in range · 26 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
Habitat climate climate answeredasked 2026-10-22
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-22NASA POWER (MERRA-2) daily 1981–2024, cell 21.50_-158.125, lapse-corrected +54 m at 6.5 °C/km; read, and set aside: NASA POWER's cell is mostly sea (48% land), so no cold floor is shown
Wikidata wikidata answeredasked 2026-10-22found by its label; its IPNI identifier 17145570-1 is Kew's for Marsilea villosa Kaulf.
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 2026-10-22none of the photographs on this page is credited to GBIF: those shown are other sources', and GBIF's were the same photographs or were set aside by the photograph rules
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 12 datasets via GBIF.org; each carries its own licence.

Cultifolio

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