Plate No. 07
Bishop's Cap
Astrophytum myriostigma
"A spineless mitre, flecked with starlight"
Native to
Limestone hills of north-eastern Mexico

History
A brief account
Named for its resemblance to a bishop's mitre, this cactus carries no spines — only a dusting of tiny white scales that catch the sun like frost. Described by Charles Lemaire in 1839 and a centrepiece of European collections ever since.
How to care for
Bishop's Cap (Astrophytum myriostigma) grows best when its natural cycle of strong light, freely draining soil and measured watering is respected. Give it bright filtered light to gentle direct sun. burns easily under harsh midday rays. Water it according to its seasonal needs: once every two weeks in summer; entirely dry from november to march. Plant it in very mineral, with crushed limestone or oyster shell. A container with an unobstructed drainage hole is essential, because moisture lingering around cactus roots can quickly lead to rot.
Keep its temperature needs in mind: 10–30°c. cool, dry winter rest below 12°c. During active growth, check the compost before watering rather than following a rigid calendar, since heat, light and pot size all change how quickly it dries. Reduce watering during cool or dormant periods, keep the plant well ventilated, and wait until the growing medium is dry before watering again.
How to propagate
From seed only — slow but reliable. Sow fresh seed on the surface of a fine, sterile cactus mix and keep it warm, lightly humid and out of harsh direct sun until germination. Once seedlings are established, increase ventilation gradually and allow longer intervals between watering to reduce the risk of damping off.
Young cacti are especially vulnerable to excess moisture. Use a small pot with excellent drainage, provide bright filtered light while roots establish, and move the new plant gradually into the light, temperature and watering conditions preferred by a mature Bishop's Cap.
Cultivation
Quick tips for care & planting
- Light
- Bright filtered light to gentle direct sun. Burns easily under harsh midday rays.
- Water
- Once every two weeks in summer; entirely dry from November to March.
- Soil
- Very mineral, with crushed limestone or oyster shell.
- Temperature
- 10–30°C. Cool, dry winter rest below 12°C.
- Propagation
- From seed only — slow but reliable.