Say it: ass-troh-FY-tum cap-rih-COR-nee. Common names: goat's horn cactus.
Where it grows
The Chihuahuan Desert of northern Mexico, mostly in Coahuila, on limestone slopes.
Size and growth
A ribbed, white-flecked body like the Bishop's Cap, but armed with long, flattened, papery spines that twist and curl like a goat's horns. Reaches 10 inches tall over many years. The variety senilis (“old man”) carries so many spines the body almost disappears. Moderate growth, flowering in 3–5 years from seed.
Flowers
Large yellow flowers with a red throat, 2–3 inches across, from the crown through spring and summer. Many consider them the best flowers in the genus.
Care
- Light: full sun to bright light; strong light keeps the spines dense.
- Water: when dry in warm months, dry in winter.
- Soil: gritty mineral mix, ideally with some limestone or crushed shell.
- Cold: tolerates brief drops to around 20°F if dry.
From seed
Easy, with germination in 7–21 days. Seedlings show their first curled spines within the first year.