• FOOD & DRINK By SARA MURRAY

ARLINGTON, Va.—Wine connoisseurs look for bouquet, clarity and taste. For the Wine Century Club, it’s all about quantity.

The club has only one membership requirement: having tried at least 100 different varieties of grape. Many members have sampled the usual array: Cabernet Sauvignon, Chardonnay, even Sangiovese. Tracking down an Ehrenfelser or Piedirosso is the challenge.

The application form includes a checklist of 185 varieties, based on the Wine Grape Varietal Table. This is a sort of periodic table of the grapes, arranged by body, acidity and color, that club president Steve De Long and his wife, Deborah, sampled and then charted. Of the most common vine species used for wines, there are 10,000 known varieties, and each variety yields a different grape.

Brooks Kraft for the Wall Street Journal

Shana Fulton enjoys a tasting earlier this month. ‘She’s the yin to my yang,’ says her wine-quaffing husband, and, noting her designated-driver status, ‘the driver to my Explorer.’

"It’s a serious hobby that’s gone awry," said member Walter Rachele, sporting a button-down shirt printed with vines, wine glasses and bottles, at a recent tasting in Arlington, Va.

Mr. Rachele, a financial analyst, carries a separate business card for his wine-related activities. It lists his four major affiliations: the American Wine Society (Wine Judge Training Instructor), the International Federation of Wine Brotherhoods, the Brotherhood of the Knights of the Vine (Master Knight) and the Wine Century Club (243rd member).

Becoming a traditional connoisseur of wine by learning to observe fine differences in flavor and aroma "gets to be very, very obnoxious," Mr. De Long said. "This is more like an adventure."

Indeed, members say, you have to drink some swill to get to 100.

Having sampled their hundred grapes, members go on to … sample more. Along the way, they get new designations, and new bragging rights. A Doppel member has tried at least 200; a Treble member, 300; a Quattro member, 400; and so on. It is perhaps more fixation than connoisseurship. Members can tick off hundreds of different grapes and their flavors, provenance and means of production. Membership is free and based on the honor system.

In the already plenty nerdy world of wine, "this is about the nerdiest wine is ever gonna get," said Jim Barker, founder of the Washington Wine Academy in Arlington, Va., the nonprofit group that hosted the Arlington tasting.

The club drew a crowd of roughly 50 current and aspiring members to the tasting with the promise of 25 "uncommon varietals," such as a Mencia from Bierzo, Spain, and a Procanico from Umbria, Italy. Among the attendees was Tom Finigan, a 35-year-old wine distributor, an instructor at the Washington Wine Academy and a member of the club.

Mr. Finigan is a curious blend himself, fascinated with the intricacies of wine, yet disgusted with what he considers wine snobbery. His wife, Shana Fulton, has a less complicated perspective. "To me it’s either good or it’s bad," said Ms. Fulton, 33. "Tom’s like ‘this, that and the other, and the grapes and the smell …’ I actually feel bad that he’s married to me."

It’s not so bad, Mr. Finigan said. His wife is content with a nice Cabernet or a Riesling. "She’s the yin to my yang," he said, and, noting her designated-driver status, "the driver to my Explorer."

One drawback to the club, more conventional connoisseurs say, is that the focus on numbers and check-off lists can limit true wine appreciation.

"I like the idea of saying let’s try different grapes," said Anthony Giglio, an author and sommelier who compiles Food & Wine magazine’s Wine Guide. But "you can’t draw a conclusion about any grape by just tasting it once."

The Wine Century Club, based in New York, has seen its ranks swell to nearly 800 members world-wide. It celebrated its fifth birthday last month with parties from Hong Kong to Virginia.

After creating the grape table while living in New York, Mr. De Long and his wife figured they weren’t alone in their grape appreciation, and started the club. Shortly after that, they moved to London, where they continued the pursuit. As the architecture business, Mr. De Long’s primary work, was pummeled, the club morphed into his full-time job. It drew $50,000 in the first quarter from enthusiasts who purchased copies of the varietal table for $25 to $35, tasting guides and wine maps of the world.

"If my luck holds out, I can continue to do this the rest of my life," Mr. De Long said.

There are tricks to reach 100 faster. Marrying a wine salesman helped Ms. Fulton, who had sampled 68 grapes by the end of the Arlington tasting. Members also recommended dating a wine judge or retiring and attending tastings around the world.

And there are a few rules. A bottle of Cento Uve blends 152 varieties of grapes and could catapult a newcomer into the club’s ranks with one sip. That’s illegal.

For now, the club’s reigning champion is Thomas Reagan, a retired airline captain in Atlanta, whose list consists of 461 grapes, a number that needed to be regularly updated in the preparation of this article.

All those tastings can take their toll on any aficionado. Mr. Barker of the wine academy admitted that "all I want when I get home is an ice-cold beer."