A sweet potato is not a yam, and a yam is not a sweet potato. Except when a sweet potato is called a yam, which is not because that sweet potato is an actual yam, but because it is a variety with softer flesh, like an actual yam. It's purely a marketing appellation, which the U.S. Department of Agriculture polices by requiring that all sweet potatoes that are called "yams" are also called sweet potatoes. I'm guessing not much money is allotted to enforcing that, because I've never seen a produce display identifying something as both a yam and a sweet potato. But to be fair, most people don't know the difference, or care to.

The sweet potato, indigenous to the Americas, is related to the morning glory and hundreds of other viney plants. It's also yet another product that we've successfully outsourced to China, which currently produces upwards of 80 percent of the world's supply. It's a bit ironic, because the yam, or at least one of its main cultivars, is native to China. (Other yam varieties come from Africa and elsewhere in Asia.)

Many American recipes using the sweet potato - like sweet potato pie - can be traced back to African slaves who incorporated the yam-like sweet potato into their traditional recipes. As the conflation of sweet potatoes and yams suggests, the two tubers have become largely interchangeable in most cuisines. Still, when you order a sweet potato pie, you'd like to think that you're getting a pie made with sweet potatoes, not yams. Unless the yams are really sweet potatoes, of course.

For this Food Fight, I intended to pit House of Pies (on Kirby) against one of the most underrated dessert shops in Houston, the Third Ward's outstanding Not Jus' Donuts. Unfortunately, Not Jus' Donuts was out of sweet potato pie yesterday and wasn't going to have any more until Saturday. "You got me wishing we did have some," commiserated the genial counterman. "It's really good. And now I want a piece too." Did someone say followup story? In the meantime, I went with the Midtown upstart Natachee's Supper 'n Punch.

To the judging!

House of Pies (7 3/8 oz for $3.25)

The sweet potato pie at House of Pies is proudly made with Louisiana yams which, it will probably not surprise you to learn, are "an exceptional type of sweet potato bred to have a soft, moist flesh, to be sweet and flavorful and very high in beta-carotene." Sure enough, the pie is bright orange. It's sweet, but not overpoweringly so, and is nicely spiked with nutmeg. The filling has a slightly nubby mouthfeel, because the sweet potatoes haven't been pureed smooth. It's a great aesthetic decision, a visual/textural cue that brings out the pie's already-strong sweet potato flavor. I had a mediocre experience at House of Pies a few years ago and haven't been back, but this pie makes me want to pre-order my Thanksgiving desserts. Tomorrow.

Natachee's Supper 'n Punch (9 oz. for $3.50)

I had high hopes for Natachee's. In the space of a few months, it's been hyped, taken to the woodshed and praised for having come into its own. I like a place that can learn from its mistakes. Also, The Beverly Hillbillies was on the TV over the bar (the episode where the Clampetts try to help Mrs. Drysdale win an art contest), and, well, they had me at "Texas tea." So I was ready to enjoy a big ol' slice of pie. Natachee's sweet potato pie is smooth and sleek and looks exactly like pumpkin pie made with canned pumpkin. Which would be fine if it still tasted like sweet potatoes, but it tasted like ... they left out an ingredient or two. Sugar, for instance. And salt. If you're in the market for a mild custardy dessert with a hint of sweet potato, look no further. It actually reminded me a lot of the alleged desserts I ate when I lived in Shanghai. It's not bad, but like most baked Chinese desserts, not very sweet and not very flavorful. More of a palate cleanser.

The Winner: House of Pies, going away. I've read enough good things about Natachee's to think this was an aberration, but there are no mulligans in Food Fight. And even if Natachee's pie was at full strength (to the extent I can imagine the Platonic ideal) they still probably would have lost. House of Pies does a fantastic sweet potato pie. Still, I have to wonder how Not Jus' Donuts would have fared.