Agave eggersiana, St Croix, Christiansted, VI, US

Agave eggersiana Trel.

Eggers' Century Plant

Climate known 4 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

Agave eggersiana, or Eggers' century plant, is an endangered species of spiky plant which grows in the Virgin Islands, in dry, exposed areas. Agave eggersiana is a perennial herb known in the wild only from the island of St. Croix of the U.S. Virgin Islands. A small number of plants remain on private land and are threatened by tourist development. Other threats include feral pigs and goats on National Park Service land. More on Wikipedia ›

The opening of Wikipedia, “Agave eggersiana”, CC BY-SA 4.0, quoted as written. Kept separate from everything derived here.

About the genus · Agave

Agave is a genus of monocots native to the arid regions of the Americas. The genus is primarily known for its succulent and xerophytic species that typically form large rosettes of strong, fleshy leaves.

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

Family

Asparagaceae

Described by

Trel.

Native to

Leeward Is. AB Ant

Wild records

12 in range· 1 open

At a glance

Warmest month

28°C

Aug, mean day; nights 26 °C (CHELSA)

Rain

1056mm/yr

12 wet months · peak Oct 146 mm (CHELSA)

Light

29–43DLI

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 Agave, which is reliably one kind of plant (archetype table). Rain rule: a sharp rainy season, May and July to December at the habitat (not shifted); the temperature curve is flat (2.6 °C of range), so no growing season is inferred. Habitat rain 1056 mm a year, wettest October at 146 mm, driest March at 38 mm (habitat calendar, northern hemisphere). Open sky over the habitat: 29 to 43 mol/m²/day. Cold floor 23.9 °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.

Cultivation

Grouped as a cactus or succulent by the genus Agave, 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 sharp rainy season, May and July to December at the habitat (not shifted); the temperature curve is flat (2.6 °C of range), so no growing season is inferred.

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

The rain rule reads a sharp season: 70% of the year's rain (788 mm of 1056 mm) falls in May and July to December. The temperature curve is flat, 2.6 °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; with a flat temperature curve there is no season to reverse, so they are not shifted for a collection elsewhere.

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 1056 mm a year, wettest October at 146 mm, driest March at 38 mm (habitat calendar, northern hemisphere).

This species’ habitat figures, with their source.

1056 mm a year at the habitat, 788 mm of it May and July to December. Wettest month October at 146 mm, driest March at 38 mm. Across the envelope cells the year's total runs 985 mm to 1137 mm (10th to 90th percentile of each cell's own year) (median year across the envelope cells, CHELSA; habitat calendar, northern 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: 29 to 43 mol/m²/day.

This species’ habitat figures, with their source.

Open sky over the habitat: 29 to 43 mol/m²/day across the year (daily light integral, median year across the envelope cells, CHELSA).

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 23.9 °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 23.9 °C, the absolute minimum 22.6 °C, no frost in 44 years (NASA POWER daily minima). Warmest: the 99th-percentile day is 29.9 °C. Monthly means: coldest night 24.1 °C in February (across the envelope cells 23.9 °C to 24.1 °C), warmest day 28.1 °C in August (median year across the envelope cells, CHELSA). Cold floor: 23.9 °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: 60 to 64% 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 6 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	26 / 25–26	25 / 25–25	25 / 25–25	26 / 26–26	27 / 27–27	28 / 27–28	28 / 28–28	28 / 28–28	28 / 28–28	28 / 28–28	27 / 27–27	26 / 26–26
Night °C	24 / 24–24	24 / 24–24	24 / 24–24	25 / 25–25	26 / 25–26	26 / 26–26	26 / 26–26	26 / 26–26	26 / 26–26	26 / 26–26	26 / 25–26	25 / 25–25
Rain mm	56 / 53–61	42 / 39–45	38 / 34–42	68 / 63–75	114 / 108–121	64 / 59–71	86 / 82–91	85 / 79–91	129 / 119–141	146 / 138–155	143 / 134–155	85 / 79–92
DLI	31 / 31–31	35 / 35–35	40 / 40–40	43 / 43–43	41 / 41–42	42 / 42–43	42 / 42–42	41 / 41–41	38 / 38–38	34 / 34–34	30 / 30–30	29 / 29–29
RH %	61 / 60–62	60 / 60–61	60 / 60–61	62 / 61–63	63 / 63–65	63 / 63–64	64 / 63–65	64 / 63–65	64 / 63–65	64 / 63–65	63 / 62–64	61 / 61–62

Each figure is the median across the 6 grid cells holding the 11 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 1444:2307 (17.775, -64.625). Over 44 years there: absolute minimum 22.6 °C, 1st-percentile night 23.9 °C, 99th-percentile day 29.9 °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 6 distinct grid cells holding the 11 in-range records; extremes and elevation at the typical cell 1444:2307 (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 18.00_-64.375, lapse-corrected +12 m at 6.5 °C/km. Elevation: ETOPO 2022, 12 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.

NativeLeeward Is. AB Ant

Kew's description“succulent perennial” · “seasonally dry tropical”· quoted from WCVP, RBG Kew (CC BY 4.0); not derived here

Map marker17.747, -64.584 · in the densest population, 12 records (100% of those in range)

Evidence usedThe map marker and the climate envelope rest on all 12 georeferenced records inside the native range; the map shows only the 1 openly licensed one, which alone would put the marker 4 km away. 1 in-range record is placed to worse than 10 km and stays 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 12 in-range records; it decides nothing.

Photographs

Photographs: no rights reserved · CC0; runcator, CC BY, iNaturalist via GBIF; prodewald, CC0, 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 Agave eggersiana, most cited first, from OpenAlex (CC0). A mention, not a cultivation source: nothing on this page is drawn from them.

Scyphophorus acupunctatus (Coleoptera: Dryophthoridae): A Weevil Threatening the Production of Agave in Mexico

Jaime Alioscha Cuervo-Parra, Víctor Hugo Pérez-España, Pablo Antonio López Pérez, Mario Alberto Morales-Ovando (2019) · Florida Entomologist

Molecular and Morphological Tools to Distinguish Scyphophorus acupunctatus Gyllenhal, 1838 (Curculionidae: Dryophthorinae): A New Weevil Pest of the Endangered Century Plant, Agave eggersiana from St. Croix, U.S. Virgin Islands

Maria Lourdes Chamorro, Joshua Persson, Christian W. Torres‐Santana, Jeff Keularts (2016) · Proceedings of the Entomological Society of Washington

Evaluation of 757 species Under U.S. Endangered Species Act review on U.S. Department of Defense lands and their potential impact on Army training

Jinelle H. Sperry, Wade A. Wall, Matthew G. Hohmann (2016) · US Army Corps of Engineers: Engineer Research and Development Center (Knowledge Core)

The flora of the American Virgin Islands / N.L. Britton.

Nathaniel Lord Britton (1918) · New York Botanical Garden eBooks

What is the evidence that invasive species are a significant contributor to the decline or loss of threatened species? A Systematic Map

Philip A. Roberts, Hilda Díaz‐Soltero, David Hemming, Martin Parr (2015)

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