Guy Clark's "Homegrown Tomatoes" was first released in 1983, but as of a Saturday morning earlier this month, only one member of the Sugarloaf Mountain Boys had ever heard the song. Based on his recollection of the John Denver cover, he was certain the chords were G-C-D.

"I hear the chords, but what's the melody?" fiddler John Barkley, who had been given a printed sheet of lyrics and lead vocal duties, carped good-naturedly. (It's hard to get too grumpy when you're standing in a garden shed, wearing an old-timey string tie.) He gamely made his way through the upbeat salute to the season's marquee vegetable, putting extra heart into lines like "all winter without 'em's a culinary bummer."

"It may sound nothing like it's supposed to, but that's how the Sugarloaf Mountain Boys do it," Barkley told his fellow bluegrass bandmates after the final chord was strummed. "I like it. That's a good song. We may have to incorporate that one."

The Midlands pickers were in a rush to master the song because they were set to perform at Rodger's Heirlooms' annual tomato tasting about 20 minutes hence. The Little Mountain event, now in its ninth year, is an opportunity for growers from across the state to compare their bounty and swap heirloom seeds. The band had no choice but to stoke the non-hybridized tomato excitement.

Among food-centric happenings, the tasting, officially known as the South Carolina Piedmont Lycopersicum Annual Tasting, or SPLAT, is unrivaled for pleasantness. Dozens of guests, mostly heirlooms enthusiasts and Rodger Winn's neighbors, poke around the Winns' substantial organic garden, where the commercial plantings include Carolina gold rice, cotton, okra, black-eyed peas, Moon & Stars watermelons, peanuts and 83 kinds of tomatoes. They rock on the front porch swing, snacking on thick slices of German Johnson tomatoes, pressed between white bread primed with mayonnaise.

Some of the attendees are as particular about their sandwiches as their seeds' pedigrees: Master gardeners Diana and James Glaser of Union bring their own wheat bread and bacon. But so long as the tomato is heirloom, Diana Glaser says she's inclined to like it: "I really think the taste is much better."

Heirloom history

At the turn of this century, very few eaters were aware of the heirloom category. Although gardeners had been clued into heirlooms since the 1980s - the 1984 publication of Carolyn Jabs' "The Heirloom Gardener" is often cited as a turning point in the pro-heirloom movement - it wasn't until 2001 that Nation's Restaurant News' noted heirlooms' menu appearances.

"Many chefs around the country (are) turning to heirloom varieties - produce grown from seeds passed down from generations - because of the promise of more intense flavor and character," the trade publication reported.

Winn's wife, Karen, says their garden supplied all of the heirlooms served at the first edition of the tomato party, held at a nearby park. "People didn't really know about the different varieties," she recalls.

Now, heirlooms are so ubiquitous that P.F. Chang's 200-plus locations this summer are serving a $7.95 Heirloom Tomato Salad, made with avocado and Thai basil. It appears that "heirloom," along with the "market-fresh" and "vine-ripened" tags that the Chinese-American chain assigns to the seasonal dish, may no longer mean as much as consumers wish it did. Like "natural," "organic" and other food words with a patina of goodness, "heirloom" isn't a guarantee of deliciousness.

That's what Cambridge food blogger Jennifer Che discovered when P.F. Chang's recruited her to sample its summer menu, including the tomato salad.

"The tomatoes were just not that flavorful and had the texture of refrigerated tomatoes," she wrote on tinyurbankitchen.com. "Perhaps they weren't vine ripened? ... Overall, we did not love this dish."

There's wide disagreement over how exactly to define an heirloom plant. The most concrete interpretation of the term is a variety that's been handed down from one generation to the next. But it's commonly understood to mean an open-pollinated plant that dates back at least 50 years. The appeal of heirlooms is they were bred for flavor, not uniform shape, disease-resistance, shipping durability or the ability to get ripe quick.

Of course, not every breeder was equally adept at isolating exquisite flavors, so some heirlooms are tastier than others. And because the heirloom designation doesn't have anything to do with growing methods, at least one tomato connoisseur has publicly suggested that heirlooms often disappoint.

Pruning heirloom field

Scientific American a few years ago published "The Case Against Heirloom Tomatoes," which asserted inbreeding made the prized tomatoes "weak and wimpy." But the Washington Post's Jane Black penned her 2009 argument on flavor, or the conspicuous lack of it. "As farmers and supermarkets realized they could extract high prices for heirlooms, they increased production," she wrote. "And, in some cases, quality fell; hence the gorgeous but mealy and bland heirloom I bought last week."

According to Black, heirlooms emerged as "a kind of mascot for the good-food movement," even if they didn't taste better than hybrids (which, unlike GMOs, are the result of longstanding agricultural practices.)

Many eaters are apparently equally willing to overlook whether a funny-looking tomato represents a real link to the past. In 2002, before heirlooms were grown commercially, Florida tomato producer Joe Procacci developed the UglyRipe, a bulging, asymmetrical "heirloom-style" tomato with shrugged shoulders. "These tomatoes can boast a significant return for retailers," current marketing materials claim, citing the "greater sense of authenticity."

So how can tomato lovers overcome heirloom hype? Buying locally grown tomatoes is one way to avoid an underwhelming heirloom.

"Water, temperature, even pressure from insects can make plants create different compounds that go into the taste or lack of it," explains Sumter County Extension Agent Amanda McNulty, host of "Making It Grow" and a SPLAT attendee. "I think that some tomatoes that aren't classified as heirlooms can be delicious, but you won't get those in the grocery store."

It's also worth learning to distinguish between heirlooms. Tomatoes are typically grouped by color - pink, black, green, red, orange, yellow and striped - and it's the black tomatoes that tend to make the strongest flavor statement.

"They kind of bite you back," says Karen Winn, who calls the blacks a "personal favorite." Popular black varieties include the Paul Robeson, Carbon, Vorlon, Black Prince and Black Cherry; the latter two appeared on TomatoFest Heirloom Tomato Seeds' 2014 "Top 10 Heirloom Tomatoes" list.

"Some people think if it's not red, it's not a tomato," Winn says, recalling when her husband brought Cherokee Purples to work. "He sliced them on a platter, and put them in the break room. The secretary went in and threw them out. When Rodger asked her about it, she said, 'Those rotten things?' "

Now, Winn adds with a smile, "All she asks for is Cherokee Purples."

Reach Hanna Raskin at 937-5560 or hraskin@postandcourier.com.