Astrophytum ornatum is the largest and tallest species of Astrophytum. Solitary and cylindrical in form it may grow up to 6.6 feet in height and up to 30 cm in width. It develops numerous white woolly flakes for protection from the sun. It flowers throughout the summer. Flowers are canary yellow and up to 7.5 cm long.
Astrophytum ornatum Nudum distinguishes for its stout almost naked dark green stem without (or with very few) white hair-tufts, on the contrary the white hair-tufts in typical plants are in broad bands, seeming to be hanging from opposing areoles and take a long time in the transition to the adult form. Up to date many botanists don't recognize the variety rank to this taxon which does not differ conspicuously from the other forms of the species
Like most cacti they're drought tolerant and need very little care and attention to grow well. Not enough sunlight and over-watering are common mistakes.
Plenty of sunshine will keep this cacti more than happy. In a glass room you may have to provide some shade during a hot summers day to prevent sunburn
Feed every 4 weeks with a Nitrogen-poor and Potassium & Phosphorus-rich fertilizer during summer
It is an excellent plant for garden rockery settings, desert type landscapes, patios and botanical gardens