Okay, I know you’d never eat a potato with pink “ears” and a mustache.

But what about one that looks kind of green tinged, either when you cut it open or sometimes just after washing it?

We know right away that it’s bad to eat green meat, green bread or green cheese – and to toss anything that meets that description.

But the green-ish potato is sort of a half-baked confusion. It doesn’t look right, but still, is it bad?

The answer is an unmistakable “yes.”

That’s because a potato that’s gone green can actually be a toxic tuber. Specifically, it contains a kind of poison called solanine, which is a result of improper storage, age and exposure to light (especially fluorescent light).

Also present in leaves and stems (and in those “sprouts” that form on potatoes), solanine, a glycoalkaloid which may also be present in other nightshade plants like tomatoes and peppers, is intended to protect the plant from disease, insects and predators. And it’s something that can make you really, really sick if you eat enough of it – with severe gastrointestinal problems similar to food poisoning.

And consumed in mega amounts, it can cause depression of the nervous system resulting in fever, convulsions, weak pulse, rapid breathing, coma, hallucinations and even death.

Now perhaps you’ve noticed a green tinge or green patches on some potatoes and ignored them or cut them off.  On the skin, that’s chlorophyll – but it should be a warning that solanine is present just under the skin (as should a bitter taste).  If you didn’t get sick after eating them, it’s because your body has some ability to handle very small amounts of this poison (traces of which are apt to be present in perfectly good potatoes). But depending on factors like your body weight and sensitivity, ingesting significant levels can cause you to experience ill effects anywhere from 30 minutes to 8 to 12 hours afterwards.

While large-scale cases of potato poisoning are not something you often hear about, they have occurred – especially in situations where people have eaten rotting potatoes, or where potatoes were left over from the previous year and poorly stored.

The bottom line: keep all potatoes in a cool, relatively dark place.  Never eat a potato once it’s started sprouting — and if a potato appears to be green, it’s a far better idea to discard it than simply cut off the green part.

In other words, go by the old rule: When in doubt, throw it out.