Who's asking: Matt Prager, Brooklyn, NY
Let us discuss, for a moment, this notion of "edible." My American Heritage Dictionary defines "edible" as "fit to be eaten," thus making the term more a matter of opinion than of fact. Things I don't consider edible include mushrooms, hearts of palm, and most forms of seafood. I once dated a man who believed that celery was a practical joke.
So let's break this question down into component parts, the first being, "Will it kill you?" and the second being, "Can you stand the taste?"
The leaves of pepper plants are not poisonous. I found a Thai recipe that used them as a base for something made of shaved coconut, sugar syrup and nuts; I'd eat almost anything as a base for shaved coconut, sugar syrup and nuts, but Anna would not consider that edible.
On the second question, I happen to have three small capiscum plants on my deck, so I tried one of the leaves this morning. It tasted like a leaf. Kind of like grass, really, or like anything you'd pull off a bush (if childhood memories serve). Not something I'd put in a salad, unless I was starving. An interesting, kind of nutty aftertaste, but downright nasty while I was chewing it.
Tomorrow's question: how did curiosity kill the cat, anyway?