T he Astrophytum myriostigma Fukuryu Type A Nudum is a distinctive cultivated form of Bishop’s Cap Cactus, prized for its unusual rib development and smooth green body. Unlike the typical Astrophytum myriostigma, the nudum form has little to no white flecking, allowing its green, blue-green, or gray-green epidermis to remain clearly visible. Type A Fukuryu is recognized by its additional, partially developed ribs, which give the cactus a distinctive layered appearance as it matures.
This rare collector’s cactus is especially appealing because of its unusual structure and relatively slow growth.
The additional ribs usually develop between the main ribs and do not extend completely to the crown or form their own areoles.
These irregular growth patterns make each plant somewhat different, so it works particularly well as a specimen cactus for a sunny windowsill, greenhouse, decorative container, or dry succulent collection.
The plant has a rounded to somewhat columnar, spineless body and typically remains solitary. Mature specimens can eventually reach around 24 inches tall, although cultivated plants often remain much smaller for many years because of their slow growth.
The flowers appear from the crown once the cactus reaches maturity and are generally yellow to creamy yellow, sometimes with orange or reddish coloring toward the center. Bees and other flower visitors can pollinate Astrophytum flowers, helping the plant produce seeds.
For growing indoors, use a porous, well-drained cactus mix soil containing plenty of pumice, perlite, lava rock, or coarse grit. Water thoroughly, then allow the soil to dry completely before watering again.
Place the plant beside a south- or west-facing window where it receives several hours of bright direct sunlight, or provide a suitable grow light when natural light is insufficient. Keep temperatures around 65–85°F during active growth, with cooler winter temperatures acceptable as long as the plant remains dry and protected from frost. Low humidity and good air circulation are preferable.
Outdoors, this cactus is best suited to USDA Zones 9–11 and should be protected from frost, prolonged cold, and excessive rain.
Give it full sun or very bright light, gradually acclimating indoor-grown plants before exposing them to strong outdoor sunlight.
Water deeply but infrequently during the growing season, allowing the soil to dry completely between waterings, and reduce watering considerably during winter dormancy.
Feed with a diluted, low-nitrogen NPK fertilizer during spring and summer. Pruning is generally unnecessary; simply remove damaged or diseased growth when needed.
One of the most interesting features of this cultivar is how its extra ribs change the appearance of the cactus without creating the heavily textured surface seen in some other Fukuryu forms. Type A is primarily recognized by its partially developed additional ribs, while Type B develops more pronounced irregular wart-like structures. This distinction makes Type A Nudum particularly useful for collectors who appreciate unusual Astrophytum forms. The plant itself is not known for attracting large numbers of pollinators, but its seasonal flowers can provide nectar and pollen for visiting insects.
The Bottom Line
Overall, the Astrophytum myriostigma var. Nudum (Type A) is a slow-growing collector cactus valued for its smooth green body and unusual partially developed ribs. Its distinctive form, yellow flowers, and compact growth make it an excellent specimen for cactus collections, sunny windowsills, and greenhouses. Provide strong light, gritty, fast-draining soil, careful watering, low humidity, light fertilization, and protection from frost and prolonged moisture to keep this unusual cactus healthy.
Growers Quick Reference Guide - Key Features
- Description
- Key Plant Features
T he Astrophytum myriostigma Fukuryu Type A Nudum is a distinctive cultivated form of Bishop’s Cap Cactus, prized for its unusual rib development and smooth green body. Unlike the typical Astrophytum myriostigma, the nudum form has little to no white flecking, allowing its green, blue-green, or gray-green epidermis to remain clearly visible. Type A Fukuryu is recognized by its additional, partially developed ribs, which give the cactus a distinctive layered appearance as it matures.
This rare collector’s cactus is especially appealing because of its unusual structure and relatively slow growth.
The additional ribs usually develop between the main ribs and do not extend completely to the crown or form their own areoles.
These irregular growth patterns make each plant somewhat different, so it works particularly well as a specimen cactus for a sunny windowsill, greenhouse, decorative container, or dry succulent collection.
The plant has a rounded to somewhat columnar, spineless body and typically remains solitary. Mature specimens can eventually reach around 24 inches tall, although cultivated plants often remain much smaller for many years because of their slow growth.
The flowers appear from the crown once the cactus reaches maturity and are generally yellow to creamy yellow, sometimes with orange or reddish coloring toward the center. Bees and other flower visitors can pollinate Astrophytum flowers, helping the plant produce seeds.
For growing indoors, use a porous, well-drained cactus mix soil containing plenty of pumice, perlite, lava rock, or coarse grit. Water thoroughly, then allow the soil to dry completely before watering again.
Place the plant beside a south- or west-facing window where it receives several hours of bright direct sunlight, or provide a suitable grow light when natural light is insufficient. Keep temperatures around 65–85°F during active growth, with cooler winter temperatures acceptable as long as the plant remains dry and protected from frost. Low humidity and good air circulation are preferable.
Outdoors, this cactus is best suited to USDA Zones 9–11 and should be protected from frost, prolonged cold, and excessive rain.
Give it full sun or very bright light, gradually acclimating indoor-grown plants before exposing them to strong outdoor sunlight.
Water deeply but infrequently during the growing season, allowing the soil to dry completely between waterings, and reduce watering considerably during winter dormancy.
Feed with a diluted, low-nitrogen NPK fertilizer during spring and summer. Pruning is generally unnecessary; simply remove damaged or diseased growth when needed.
One of the most interesting features of this cultivar is how its extra ribs change the appearance of the cactus without creating the heavily textured surface seen in some other Fukuryu forms. Type A is primarily recognized by its partially developed additional ribs, while Type B develops more pronounced irregular wart-like structures. This distinction makes Type A Nudum particularly useful for collectors who appreciate unusual Astrophytum forms. The plant itself is not known for attracting large numbers of pollinators, but its seasonal flowers can provide nectar and pollen for visiting insects.
The Bottom Line
Overall, the Astrophytum myriostigma var. Nudum (Type A) is a slow-growing collector cactus valued for its smooth green body and unusual partially developed ribs. Its distinctive form, yellow flowers, and compact growth make it an excellent specimen for cactus collections, sunny windowsills, and greenhouses. Provide strong light, gritty, fast-draining soil, careful watering, low humidity, light fertilization, and protection from frost and prolonged moisture to keep this unusual cactus healthy.
