Architectural and slow-growing, this small columnar cactus stacks up like a fairy-tale tower with cream-striped stems that catch the eye even in a small space. The variegation stays sharp indoors near a sunny window, where the plant's modest water needs make it one of the easiest succulents to keep alive.

Pot it in cactus soil and water sparingly—every three weeks or so during the growing season, even less in winter. A windowsill in a warm room is all it asks.