Growth Habits: Astrophytum myriostigma is in fact a columnar cactus, and can attain anything up to 2 feet high (60 cm) by 8 inches in diameter (20 cm) but a cultivated plant this size is extremely rare and normally it would take a number of years for the plant to even show signs of being columnar. It can normally have anything between 4 to 6 ribs (usually 5) and no spines. Some plants known as ‘nudum’ have a smooth green epidermis but most others have small white markings (commonly called flecking) to a lesser or greater degree, sometimes so heavily marked that they look like a piece of sculpture carved out of a block of chalk. 4 ribbed plants called quadricostatum are much sought after. Those with three ribs, tricostatum even more so. It is a fact however that hobbyists have paid good money for one of the above, only to find in a couple of years time that the plant decides to develop an extra rib. In the main the plant remains as a solitary body, but it will sometimes decide to throw offshoots from the base.
Scientific name: Astrophytum myriostigma
Common names: Bishop’s Cap, Bishop’s Mitre,
Synonym: Astrophytum columnare, Astrophytum tulense, Astrophytum myriostigma var. potosinum, Astrophytum nuda, Astrophytum myriostigma var. viescaensis, Astrophytum coahuilense, Astrophytum prismaticum, Echinocactus myriostigma, Astrophytum myriostigma var. multicostatus, Astrophytum myriostigma var. columnaris
Etymology: The generic name "Astrophytum" derives from the Greek words astron, meaning a "star" and "phyton", meaning plant. ( The Genus name implies: "star plant"). From the Greek adjective myrios meaning “countless; huge, infinite; 10,000”, and the connective vowel “O” used in botanical Latin, usually for Greek words, and the Greek word stigma meaning “point; brand, blemish, thorn” ( The specific name implies: "many points").
Origin: The plant comes from the Highlands of Central and Northern Mexico, mainly in the Chihauhaun desert. It can be found at heights above 2,000 metres.
Light: This species will take full sun to light shade.
Compost: If you do mix your own compost, your own formula should be adequate for this species.
Water: The plant requires moderate watering in summer, but is one of those plants that benefits from a dry winter rest
Flower: The glossy yellow, sweet scented flowers appear from a furry grey bud and appear almost continuously during the summer. C The plants known as A. coahuilense have a reddish orange throat.
Fruit: They are followed by a reddish fruit, 1 inch in diameter (2.5 cm).
Min. temp: Most of the books recommend a minimum temperature of 50°f. (10°C.) but I must admit to keeping mine around 5°f. lower without any ill effects.
Cultivation: The plants are not that difficult to grow. Certainly easier in my long experience than asterias and ornaturm.
Habitat: There are many threats to this species in its native habitat, not least the collection of plants for the cactus trade and conversion of its habitat for urban land use and agriculture. Many exotic grasses have also been introduced for cattle fodder and the plant is in competition with these. The landscape is very diverse and climbs up from the desert to almost alpine proportions. Of course the plant pictured above is a cultivar and its ancestors will have started life on a propagation bench rather than in the desert.
Comments: Astrophytum is my own personal favourite genus and myriostigma is my favourite species. I have searched postal plant lists and travelled some distance to get a particular plant. Some growers specialise in nothing else. There is such a variety of cultivars and hybrids etc. Variations in ribs, variations in markings or lack of them. Different colourings. I suppose the most sought after are the ‘onzuka’ plants, that have fabulous markings much like the ‘kabuto’ asterias. If you are so inclined you can pay large sums of money for some of the Far Eastern imports. A packet of seed is much cheaper and you never know you may get some fabulous plants.