Lauu, CC BY, iNaturalist via GBIF · observed growing wild

Gymnocalycium reductum (Link) Pfeiff. ex Mittler

Cactaceae

Climate known 17 photographs Cactus or succulent

Every figure on this page is derived from public data by a stated rule and says its source; nothing here is written by a person or a model, except the Wikipedia passage, which is quoted and marked as such. How it is made.

Summary

Gymnocalycium reductum is a species of Gymnocalycium from Uruguay and Argentina.

Text from Wikipedia, “Gymnocalycium reductum”, CC BY-SA 4.0, quoted as written. Kept separate from everything derived here.

About the genus · Gymnocalycium

Gymnocalycium, commonly called chin cactus, is a genus of about 70 South American species of cactus. The genus name Gymnocalycium refers to the flower buds bearing no hair or spines. In a 2023 classification of the tribe Cereeae, it was placed as the only genus in the subtribe Gymnocalyciinae, having formerly been placed in the subtribe Rebutiinae.

Text from Wikipedia, “Gymnocalycium”, CC BY-SA 4.0, quoted as written.

Family

Cactaceae

Described by

(Link) Pfeiff. ex Mittler

Native to

Argentina Northeast, Uruguay

Wild records

67 in range· 14 open

At a glance

Warmest month

27°C

Jan, mean day; nights 16 °C (CHELSA)

Rain

999mm/yr

12 wet months · peak Oct 116 mm (CHELSA)

Light

13–50DLI

mol/m²/day, winter to summer, open sky (CHELSA shortwave)

In short condensed by rule from the cultivation cards · not written by a person

Grouped as a cactus or succulent by the genus Gymnocalycium, which is reliably one kind of plant (archetype table). Rain rule: a summer growing season, April to October in the northern hemisphere (October to April at the habitat, southern). Habitat rain 999 mm a year, wettest October at 116 mm, driest June at 40 mm (habitat calendar, southern hemisphere). Open sky over the habitat: 13 to 50 mol/m²/day. Cold floor -3.6 °C (1st-percentile habitat night, NASA POWER).

Each sentence is one card's own one-line form, written by the same rule as the card (Its year, Rain, Light, Temperature); the note cannot say what a card does not. Months are given for the northern hemisphere (set your site in Settings to change this), and the habitat's own alongside. The cards · the figures.

Also known as Cereus reductus Link.

Cultivation

Grouped as a cactus or succulent by the genus Gymnocalycium, which is reliably one kind of plant (archetype table). The table holds no figure for this group, which spans too much for one minimum; the cold floor is the habitat's alone, and no prose comes from the table.

Its year Rain rule: a summer growing season, April to October in the northern hemisphere (October to April at the habitat, southern).

This species’ habitat figures, and what two fixed rules read from them.

The rain rule reads a summer growing season: 70% of the year's rain (742 mm of 999 mm) falls in October to April, warmer than the year (wet-season mean 17.0 °C against a yearly mean of 13.2 °C). Months are the habitat's, southern hemisphere; shifted six months for a northern-hemisphere collection: April to October.

Read from the median year of CHELSA monthly rainfall and mean temperature across the envelope cells: 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 gives a season to reverse. A reading of the curves, not an observation of the plant.

Rain Habitat rain 999 mm a year, wettest October at 116 mm, driest June at 40 mm (habitat calendar, southern hemisphere).

This species’ habitat figures, with their source.

999 mm a year at the habitat, 742 mm of it October to April. Wettest month October at 116 mm, driest June at 40 mm. Across the envelope cells the year's total runs 916 mm to 1044 mm (10th to 90th percentile of each cell's own year) (median year across the envelope cells, CHELSA; habitat calendar, southern hemisphere).

CHELSA monthly precipitation, median year across the envelope cells. The rain that falls where the species is recorded; nothing about how the plant takes water.

Light Open sky over the habitat: 13 to 50 mol/m²/day.

This species’ habitat figures, with their source.

Open sky over the habitat: 13 to 50 mol/m²/day across the year (daily light integral, median year across the envelope cells, CHELSA; the lowest 10th-percentile month across the cells is 12, the highest 90th-percentile month 50).

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.

Warmth and air Cold floor -3.6 °C (1st-percentile habitat night, NASA POWER).

This species’ habitat figures, with their source.

Temperature

Coldest: the 1st-percentile night over 44 years at the typical cell is -3.6 °C, the absolute minimum -6.0 °C, about 34 frost nights a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 35.9 °C. Monthly means: coldest night 2.7 °C in July (across the envelope cells 1.7 °C to 4.5 °C), warmest day 26.6 °C in January (median year across the envelope cells, CHELSA). Cold floor: -3.6 °C, which is the 1st-percentile night over 44 years at the typical cell (NASA POWER).

NASA POWER daily minima and maxima 1981–2024 at the typical cell, lapse-corrected to its elevation; CHELSA monthly means, median year across the envelope cells, CHELSA. The cold floor is the figure named in its sentence. Not a measured survival limit for any plant in a pot.

Humidity

Relative humidity at the habitat: 52 to 62% across the year (monthly means, median year across the envelope cells, CHELSA). A figure about the air, saying nothing about how the plant takes water.

CHELSA relative humidity, median year across the envelope cells.

The figures the cards read from are in Climate below, and where they came from in Natural habitat.

Climate across the habitat

day night rain 10th–90th percentile across 24 habitat cells cold quarter: the three months around the coldest night extremes over 44 years at the typical cell, marked at the edge: undated DLI, mol/m²/dayRH %each on its own scale

Figures by month

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Day °C	27 / 25–28	25 / 24–26	23 / 21–23	19 / 17–19	15 / 13–16	11 / 10–13	11 / 10–12	13 / 12–14	15 / 14–16	19 / 17–19	22 / 20–23	25 / 24–26
Night °C	16 / 14–17	15 / 13–16	13 / 12–14	10 / 8–11	7 / 5–8	4 / 3–5	3 / 2–5	4 / 3–5	6 / 4–6	9 / 7–9	11 / 9–12	14 / 12–15
Rain mm	112 / 101–116	108 / 93–116	112 / 94–125	87 / 76–92	59 / 53–70	40 / 31–52	42 / 34–53	46 / 40–55	70 / 59–75	116 / 92–126	96 / 86–104	111 / 91–118
DLI	48 / 47–49	42 / 40–42	32 / 30–32	23 / 22–23	16 / 15–16	13 / 12–13	14 / 14–15	20 / 19–21	28 / 27–29	37 / 35–38	45 / 43–46	50 / 48–50
RH %	53 / 52–59	56 / 55–60	58 / 57–61	59 / 57–61	61 / 59–62	62 / 59–63	61 / 59–63	57 / 56–61	56 / 55–61	55 / 54–61	54 / 52–60	52 / 51–59

Each figure is the median across the 24 grid cells holding the 60 in-range records, with the 10th–90th percentile span across those cells after the slash where it differs. Extremes and elevation were read at the typical cell 2558:2354 (-37.925, -62.275). Over 44 years there: absolute minimum -6.0 °C, 1st-percentile night -3.6 °C, 99th-percentile day 35.9 °C. Normals: CHELSA V2.1 1981–2010 climatology, 0.05° cells (each the mean of ~36 1 km pixels). Envelope: median and 10th–90th percentile of each month across the 24 distinct grid cells holding the 60 in-range records; extremes and elevation at the typical cell 2558:2354 (its coldest month's mean night nearest the median across cells); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell -38.00_-62.500, lapse-corrected +64 m at 6.5 °C/km. Elevation: ETOPO 2022, 326 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 every in-range record's cell, not at the marker.

Openly licensed records inside the range, framed on where they fall.

NativeArgentina Northeast, Uruguay

Kew's description“succulent subshrub” · “subtropical”· quoted from WCVP, RBG Kew (CC BY 4.0); not derived here

Map marker-38.055, -62.067 · in the densest population, 36 records (54% of those in range)

Evidence usedThe map marker and the climate envelope rest on all 67 georeferenced records inside the native range; the map shows only the 14 openly licensed ones, which alone would put the marker 3 km away. 7 in-range records are placed to worse than 10 km and stay on the map but off the climate.

The map markerthe map marker: the openly licensed record nearest the middle of the densest 1° population of the 67 in-range records; it decides nothing.

Photographs

Photographs: Romi Galeota Lencina, CC BY, iNaturalist via GBIF (6); Lauu, CC BY, iNaturalist via GBIF; Valentín Alfano, CC BY, iNaturalist via GBIF.

Photographs: iNaturalist did not answer when this page was built; what is shown came from the sources that did.

Papers naming this species

Works whose title or abstract names Gymnocalycium reductum, most cited first, from OpenAlex (CC0). A mention, not a cultivation source: nothing on this page is drawn from them.

Occurrence Download