Question
I have a beautiful Peace Lilly and have moved it into our sun room where it get partial morning sun but the problem is I have a cat and I wasn't sure if the plant is posioneous to animals.  My dog doesn't bother it just the cat.

Answer
Interesting question.  Because your Peace Lily -- Spathyphyllum to botanists -- is listed on many "Poisonous Houseplants" lists.  While I am not impressed by other people's lists (they put Poinsettas on these all the time and those are NOT poisonous), this one is worth considering.

Here's why.

Spathyphyllum sap is toxic in large quantities.  In humans it causes immediate discomfort (burning inside the mouth if eaten) before that point is reached.  In pets, especially mammals, the symptoms will be similar.

"Calcium Oxalate" is what makes Spathyphyllums -- and some other houseplants -- poisonous.  Point of information: Sometimes Cats (as well as People and Dogs) develop painful bladder stones.  The stones are actually made of Calcium Oxalate crystals.

Wikipedia says Calcium Oxalate "is a chemical compound that forms needle-shaped crystals."  You will find it, they say, in the stalk of the "painfully poisonous" Dumbcane, aka Dieffenbachia, which produces the "most severe reactions" of these kinds of toxic housepants, causing pain and swelling on lips, tongue, mouth, eyes or skin.  Simply swallowing a small amount of Calcium Oxalate will burn the inside of the mouth and throat, sometimes swelling and choking.  Larger amounts cause abdominal pain and cramps, breathing problems, even convulsions, coma and death.

People and pets usually survive brushes with these plants.  But even with treatment, anyone who survives eating Dieffenbachia for dinner is still looking at permanent liver and kidney damage.  And so, Dee, my friend, it seems to me that if your Cat does not eat enough of your Peace Lily to get stomach cramps or other symptoms, fact is, this chemical is in the Cat's bloodstream and it is going to be destructive.  It's not like, say, you let the Cat out and it wasn't hit by a car, no harm done.  There is harm; you may not see it, but it's there, and you would rather it wasn't.  Kidneys and livers are vital organs, like a heart.  You need them until you die.

Craigslist is great for selling everything, at least in the New York Metropolitan area.  Odds are you are hundreds or even thousands of miles from here so the market might be different.  Sell your Spathyphyllum.  It's tax-time; give it to a nonprofit group and take a deduction.  Get it out of the house.  Play it safe.

There are so many houseplants with no risk.  Why take the risk.

A person like you, with a green thumb, could grow anything.

Thanks for writing.