Opuntia basilaris Engelm. & J.M.Bigelow

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

The rain rule reads a winter growing season: 70% of the year's rain (129 mm of 176 mm) falls in November to March and August, cooler than the year (wet-season mean 13.5 °C against a yearly mean of 18.5 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: February and May to September.

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.

This species’ habitat figures, with their source.

176 mm a year at the habitat, 129 mm of it November to March and August. Wettest month February at 30 mm, driest June at 2 mm; 1 month under 5 mm. Across the envelope cells the year's total runs 112 mm to 375 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.

This species’ habitat figures, with their source.

Open sky over the habitat: 19 to 55 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 17, the highest 90th-percentile month 55).

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.

This species’ habitat figures, with their source.

Coldest: the 1st-percentile night over 44 years at the typical cell is -4.1 °C, the absolute minimum -9.7 °C, about 34 frost nights a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 43.8 °C. Monthly means: coldest night 3.0 °C in January (across the envelope cells -1.2 °C to 7.2 °C), warmest day 36.4 °C in July (median year across the envelope cells, CHELSA). Cold floor: -4.1 °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.

Relative humidity at the habitat: 36 to 48% 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.