Astrophytum

Astrophytum asterias

Sand Dollar Cactus

Astrophytum asterias is a small, spineless succulent cactus from the arid scrublands of northeastern Mexico and southern Texas, where it sits flush with gritty, fast-draining soil under strong sun. Grow it in a sharply draining mineral mix and water deeply only when the soil has gone completely dry to the bottom of the pot, erring on the dry side since it stores water and rots when kept moist. Give it the brightest, sunniest spot you have, and water sparingly or not at all through winter dormancy.

Astrophytum myriostigma

Bishop's-cap

Astrophytum myriostigma is a spineless, water-storing cactus from the arid highlands of northeastern Mexico, so it wants bright sun and a gritty, fast-draining mineral mix. Water deeply only when the soil has gone completely dry through to the bottom of the pot, then let it dry out fully again before the next watering. Sitting in damp soil is the main way this plant dies; in winter it rests and needs far less water.

Astrophytum ornatum

Monk's-hood

Astrophytum ornatum is a slow-growing succulent cactus from the arid scrublands of northeastern and Gulf Mexico, built to store water and endure drought. Give it a gritty, sharply draining mineral mix and the brightest spot you have, ideally direct sun. Water deeply only once the mix has dried out completely, roughly every 14 to 28 days in active growth, and far less in winter — let it stay nearly dry when cool and dormant, as it rots easily if kept wet.