CASTROVILLE >> Quietly, over the past two decades, the beloved California artichoke has undergone a radical transformation.

It’s not always easy to see from the outside — a studied eye can spot it — but an ambitious program to produce high-yielding, year-round artichokes has altered the flavor, color, texture and even the shape of them.

This revolution has uprooted thousands of acres of heirloom artichokes across Castroville — the “Artichoke Center of the World” — and replaced them with hybrids. Now, it’s pitting technology against tradition and playing out at farm stands and on dinner tables across the country.

The new varieties are cheaper to grow, have a longer shelf life and resist diseases, said Steven Fennimore, a UC Davis plant science professor.

But what about flavor?

“You can argue about taste all day,” he said, “but I won’t get into that.”

In many ways, the artichoke is no different than countless other fruits and vegetables bred to increase production and extend their seasons and shelf life. But to Californians who grew up eating artichokes on Easter — the dark green water could dye an egg! — there’s something extra special about them.

The artichoke is the state vegetable. It’s a thistle. It’s fun to eat. Out-of-state guests often don’t know which side of the leaf to bite and scrape. Aha! Marilyn Monroe, as a 22-year-old starlet in 1948, was named the very first Castroville Artichoke Queen. A bar on Main Street, just down from the landmark Giant Artichoke, is named the Norma Jean. And nearly every family growing them here — from the Pezzinis to the Scattinis and Tottinos — has been doing it for four and five generations.

The artichoke is ours.

Next month, at the Castroville Artichoke Festival, some of the newer varieties will be on full display.

But, alas, the original Castroville artichoke revered for its umami nuttiness and big tender heart — the Green Globe heirloom — is a vanishing breed, raised now on just a few hundred acres here. Grown from the same root stock imported by Italian immigrants a century ago, this heirloom once dominated tens of thousands of acres in Monterey County.

Now some of the best of the new varieties are grown not in the coastal mist of a Castroville spring, but during the fall and winter, in — of all places — the desert of Southern California’s Coachella Valley.

Some of the new varieties are quite tasty: Spring is the natural harvest season, but artichoke lovers can enjoy the meaty and flavorful Desert Globe in the winter. Sometimes in the summer, however, shoppers can be stuck with rock-hard, softball-shaped hybrids with tight leaves that couldn’t boil their way to tenderness. Choosing an off-season artichoke can require the same scrutiny and finesse as detecting the perfect avocado.

It’s a chore that Phil DiGirolamo, who owns the renowned Phil’s Fish Market that recently moved from Moss Landing to Castroville, isn’t interested in tackling.

“We use heirlooms, and if we can’t get them, we don’t do them,” he said. He tried a hybrid variety years ago. “They were a little hard. Customers complained. They said we didn’t know how to cook an artichoke.”

In Carmel-By-The-Sea, the tony tourist town down Highway 1, chef Jonny Black at Chez Noir won’t serve anything but heirlooms. His sous-chefs pick them up from Pezzini Farms roadside market on their way to the restaurant. On a recent menu, he listed “Spring Lamb Tartare” with “Pezzini Artichoke.”

“They’re just so full of flavor,” he said as he used a paring knife to get to the hearts of baby artichokes he fried Roman-style with Meyer lemon.

Mimicking that flavor is the goal for artichoke giant Ocean Mist, the Castroville-based company that produces more than 70% of California’s $45 million annual artichoke crop. The company packs more than 68 million artichokes each year — overwhelmingly the new varieties — and has been leading the desert artichoke program that, after a rocky start, is producing some of its best results in recent years.

“We recognize that there’s no point in breeding an artichoke if it doesn’t deliver on that really delicious consumer experience,” said Mark Munger, Ocean Mist’s marketing director.

For a vegetable that rarely gets a second chance to make a first impression — Midwesterners are the least likely to have tried one — the company’s in-house, blind-tasting trials have become more important than ever.

On a cool morning recently, Kevin Brink, Ocean Mist’s chief plant breeder, steps into his transplanted test plot in Castroville so close to the ocean you can smell the saltwater.

He is hoping the winter variety he cultivated in the desert — the patented desert globe — will thrive in the summer in Monterey County and replace the tougher and stringier hybrids grown there now.

“The heirlooms are what we benchmark against,” said Brink, who compares the new varieties to a small crop of heirlooms the company still grows here on 40 acres.

In essence, an artichoke is a flower bud, picked before it blooms. The fundamental difference between the heirlooms and the newer varieties is how they are grown. Heirlooms are perennials that sprout from the same root stock each spring that remains in the ground year round and farmers divide over time. They require intensive labor and constant vigilance against rodents that burrow through the fields, chomp on the roots and can kill whole plants. The artichokes are rounded with a slightly tapered top.

The newer varieties, some of which still are called Globes or less glamorous names like F1, are annuals, produced from seeds that start in greenhouses before transplantation to the fields.

Planted in staggered windows of time and place, the seedlings produce fresh artichokes year-round that are bred to be more disease-resistant. They tend to be paler green and sometimes elongated.

At Pezzini Farms just off Highway 1 in Castroville, Sean Pezzini is sticking with the heirlooms, which have become a special niche market for his family.

“It’s kind of like an old vine grape — that rooting system has been in the ground for years and years,” said Pezzini, 34, a fourth-generation farmer. “It just feels good for me that my great-grandfather was farming the same variety and I’ve stuck to it knowing that it is the best.”

He doesn’t fault other farmers growing the hybrids — he’s related to some of the families who have been running Ocean Mist for 100 years. He has seen a clear improvement in some of the new varieties over the past five years, and when his heirloom crop is picked over by early June, he sells in his farm store on Nashua Road some of the best summer hybrids or winter Desert Globes.

Ocean Mist — whose slogan is “Eat Your Heart Out” — is confident that with its newer varieties, including robust purple ones, the artichoke industry is on the “bleeding edge of a renaissance.”

To California artichoke connoisseurs, nothing matters more than taste.

If the new breeds of hybrids don’t catch up in flavor, the artichoke industry runs the risk of suffering a similar fate that befell California cantaloupes a decade ago. The industry focused on shelf life and “the flavor was basically left behind,” said UC Davis professor emeritus Trevor Suslow.

“They’ve worked hard over the last five or six years to get a lot of that back.”