Curiosities: Why do cats seem compelled to eat some plants, like my poor aloe, and ignore others?

Cats may devour some plants but ignore others as a simple matter of taste, says Sandra Sawchuk, a clinical instructor at the School of Veterinary Medicine. “It’s each to his own. I like romaine lettuce over iceberg; cats can have their own desires.” Although cats are carnivores, they may have grown accustomed to eating plant material found in their prey’s intestines, Sawchuk notes.

Some plants, notably catnip, make cats feel good, Sawchuk says. “If I eat this, I am going to get spacy, and I like that feeling.” Some cats also like spider plants, which contain compounds related to opium. “Or cats learn that certain plants will act as a purgative, causing them to vomit if they have an upset stomach,” Sawchuk says.

But plants can also be poisonous. Asiatic lilies, including Easter lilies, are a key cause of concern. “Ingesting even a tiny amount can put a cat into kidney failure,” Sawchuk says.

Owners should separate cats from toxic plants, but also deal with the many cats that like plants. Owners may want to offer their cats edible sprouts, chopped lettuce, or the “kitty grass” sold in pet stores. Sawchuk recommends that cat owners check reputable web sites for lists of toxic and nontoxic plants, and make sure to place any toxic plants well beyond reach.

Reader beware: The ASPCA says aloe vera causes vomiting, depression, diarrhea and other symptoms among cats.