A few weeks ago, I was having dinner at a renowned restaurant in San Francisco, when I noticed something a bit troubling on the menu. According to the description, the “Heirloom Tomato Salad” was made with a mix of Sweet 100 and Sungold tomatoes — both of which are hybrid varieties.

OK, big deal, they made a mistake. Well, two weeks later, I stopped at a farm stand advertising heirloom tomatoes, and sure enough, the alleged heirlooms were hybrids.

All this falsity in advertising has me wondering if the term “heirloom” is becoming just another one of those previously meaningful adjectives now relegated to the greenwashed ranks of “natural,” “local,” and “family-farm.” As someone who co-manages a farm, where we grow a number of heirloom varieties, I certainly hope it isn’t.

Heirloom vegetable varieties are open-pollinated, which means that if you save the seed, the next generation will breed “true” (assuming no accidental cross pollination). Additionally, heirlooms are from seed lines usually 50 years-old or older. Granted, this stipulation about age is a somewhat vague marker. Since the term “heirloom” hasn’t been standardized in the same way that the federal organic label has, it’s open to some creative interpretation. Green Zebra tomatoes, for example — often called heirlooms — are open-pollinated, although they were first bred about 25 years ago.

One thing is for sure: heirlooms are not hybrids, which are newer varieties bred for increased production and vigor. Unlike our Brandywine and Garden Peach tomatoes, seeds from hybrid tomatoes will not produce the same fruit from which they were saved.

Furthermore, heirlooms are often more difficult to grow than hybrids. They don’t grow as vigorously or produce as abundantly. In addition to having incredible flavor, it’s important to me and the people with whom I farm to keep these seed lines alive as a matter of principle. Growing heirlooms maintains diversity within the rapidly dwindling gene pool of agricultural crops, and selling them to our delighted CSA members cultivates a demand for them. And although we’re not yet expert seed savers, open-pollinated varieties keep us from being reliant on the seed company every year. Take that, Monsanto.

So, ye tomato marketers, no more cheating. Let’s call an heirloom an heirloom.