Poisonous Plants: Dose Makes the Poison

Q. I have a volunteer gopher plant in my front yard that I nurtured into a bush.  I noticed that something is eating its leaves.  We have a great deal of rabbits in our area. Can it be rabbits?  I thought that the Gopher plant was poisonous even to rabbits.

What does gopher plant look like?

A. I assume we are thinking of the same plant. It is a euphorbia with white latex sap coming from a damaged stem, similar to the white sap you see in poinsettia which is also a euphorbia. We tend to react to poisonous plants with fear but there are degrees of toxicity when we call something poisonous.

            I watched a professor of mine in floriculture on television take a poinsettia leaf and eat it. He didn’t die or even get sick. He was demonstrating that the plant is toxic but it is the “dose that makes the poison”. If he had eaten many leaves the story would be different. Even table salt is poisonous if we eat enough of it.

            So it is possible for an animal to eat “poisonous” plants and survive. I have heard that some livestock will eat gopher plant in the range with no ill effects. They just don’t eat a lot of it and only when browsing is poor. Just like us, animals like to eat things that taste good.