Um, is it supposed to work this way?

I recently read that sweet potatoes grow great here in Arizona because of the heat. Sweet potatoes apparently love heat. When I saw pictures of a sweet potato plant online, I was hooked. These babies are gorgeous. So I got a couple of organic sweet potatoes at Whole Foods, stuck 'em in some water, and waited.

The first one is doing exactly what I would have expected. White roots that look a little like dental floss are growing out of the bottom into the water. All's well. The second one looks like this:

Green leaves are growing out of the bottom and into the water. Not what I expected at all! But pretty interesting. I guess I'll get some popcorn, sit back, and watch the show. Let's see what happens!