About
Mammillaria glassii is a clustering cactus from north-eastern Mexico, prized by growers for its dense white spines and pink flowers. It has two subspecies.
Care at a glance
- Pet safety
- Listed as non-toxic to pets, but the sharp spines can cause injury. General guidance for the genus
- People
- Listed as non-toxic to humans, but the sharp spines can cause injury. General guidance for the genus
- Light
- Ample sunlight.
- Water
- Let the soil dry out completely between waterings; stop watering while dormant in winter. General guidance for the genus
- Temperature
- Grows best at about 21–27 °C (70–80 °F); prefers a cool winter rest at 7–13 °C (45–55 °F). General guidance for the genus
- Soil
- Needs sharp drainage.
- Pot
- Best grown in shallow pots.
- Propagation
- Seed, or by dividing offsets (pups). General guidance for the genus
- Growth rate
- Slow. General guidance for the genus
“General guidance for the genus” marks advice sourced for the genus as a whole rather than this species.
Field notes
Morphology
Clusters of rounded stems entirely hidden by fine white spines and bristly white axillary hairs up to 25 mm long; roots are sparse. In subsp. glassii stems start about 3 cm across and become cylindrical to 10 cm tall, with 50–60 white radial spines and one golden-amber central that may be hooked. Flowers are pale pink; the edible fruits turn from green to pink.
Distribution & habitat
Endemic to Mexico on steep rock, often in shade. Subsp. glassii grows in Coahuila, Nuevo León and Tamaulipas at 1,450–2,250 m; subsp. ascensionis grows at 2,400–2,750 m in Nuevo León in moss and limestone crevices on cliffs that get sun only in late afternoon.
Cultivation notes
All forms are easy to grow if given sharp drainage, shallow pots and plenty of sun. Subsp. ascensionis, with larger, showier flowers, is the more popular of the two.
History & etymology
Described in 1968 by Bob Foster and named after Charlie Glass; its discovery caused a stir among cactus collectors.
Habitat
- Altitude
- Not recorded
- Altitude class
- —
- Native to
- Mexico
- IUCN status
- Least concern
Cultivation
- Difficulty
- easy
- Temperature
- Grows best at about 21–27 °C (70–80 °F); prefers a cool winter rest at 7–13 °C (45–55 °F).
Text adapted from Wikipedia, CC BY-SA 4.0.
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