Miquelopuntia is a monotypic genus, endemic to Chile, distributed from about the 30th latitude south to about the 27th latitude. The plants form thickets, sometimes 2–5 m in diameter, with multiples populations covering whole hillsides. They often grow in association with Echinopsis chiloensis, species of Eriosyce, Copiapoa and Eulychnia.
The plants grow to about 60 cm high, with new growth joints often reaching 8–10 cm in length. The spines are divided into radial and central groups. While the radials are no more than 1cm long, the centrals may reach 4–6 cm.
Growing in colonies 2 to 5 meters broad; stems cylindric, much branched, usually less than 1 meter high, but occasionally 1,5 meters high, with numerous lateral branches; branches rather short, usually only 8 to 20 cm long, thick (5 to 6 cm diam.); old branches bluish green, with low tubercles sometimes 2 cm long; young joints bright green, with high tubercles flattened laterally; spines tardily developing, but formidable on old branches, very unequal, in clusters of 10 or more, the longest ones nearly 10 cm long, whitish in age; glochids numerous, brownish, caducous; leaves minute, 2 to 3 mm long; areolas circular, when young filled with white wool, in age somewhat elevated on the areolas.
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Miquelopuntia miquelii FK 1230 from the Marquesa Canyon, which is also the southern end of the distribution of the genus, has almost white flowers. In some populations, yellow flowers have been observed.
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Miquelopuntia miquelii FK 48-A, near Totoral at 50 m with a more bluish body, which Backeberg described var. jilesii. This population differs also in having reddish flowers.
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Miquelopuntia miquelii FK 1230, fruit from the Marquesa Canyon, ovate in shape with floral remnants firmly attached to the umbilicus; numerous areoles with mostly glochids; thick walled; filled with pulp surrounding the seed. All the populations observed in the southern half of the distribution of Miquelopuntia have these pulp-filled fruit.
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Miquelopuntia miquelii FK 48-A, near Totoral at 50 m. At the northern end of its distribution, the fruit is obovoid in shape. Fruit pulp appears to be absent, while glochids are reddish brown and longer.
Flowers rather variable in length, 4 to 8 cm long including the ovary, rose-colored to nearly white; petals broad, apiculate, 2 to 2.5 cm long; filaments rose-colored; ovary strongly tuberculate; areolas filled with numerous brown glochids and subtended by minute leaves; style white; stigmalobes green.
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Miquelopuntia miquelii FK 48-A, near Totoral at 50 m. The seed is without remnants of pulp, and the funicular girdle is clearly visible.
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Miquelopuntia miquelii FK 1098, showing the seed surface SEM after removal of the funicular envelope. Use of chemical etching reveals elongated cells with a high domed periclinal wall. Seeds from the southern populations have almost identical seed wall cell characteristics.
Fruit ovoid to oblong in outline nearly white; umbilicus truncate.
Seeds small, 4 mm broad.
Type Rocks of Huasco, Chile
Distribution: Chile, from Rio Choros Prov. Elqui, north of Castillo, Vallenar and Rio Huasco Prov. Huasco.
