It was more than 10 years ago in Brussels that Tom Hughes first realized that there was no museum dedicated to the potato.

He knew what he had to do: The Potato Museum now thrives in the basement of the town house Hughes and his wife Meredith rent on Capitol Hill.

"We offer this as an alternative museum," says the 41-year-old fifth grade teacher at the Potomac School in Virginia. "I feel that we have a message."

It's not a message everyone is going to hear. Entrance to the potato museum is by appointment only. There is no sign announcing its existence in the basement of the two-story yellow house at 704 North Carolina Ave. SE. There are no press releases; advertisement is by word of mouth. But that has been enough.

"One thing I don't want is for people in the District to read about the museum and just drop by," Hughes says.

That doesn't mean that he won't publicly list the museum's phone number or print a brochure embellished with praise from, among others, Washingtonian, The New York Times and The New Yorker.

Elitism is not his motivation. He just doesn't want a lot of people to be disappointed that they can't get in. The potato museum is small, just two rooms, and one of those is the size of a large walk-in closet.

The space is filled with more than 400 items on display -- out of a collection of 2,000 -- related, somehow, to the potato. There are potato mashers, potato books, potato posters, potato sacks (including one made into a man's blazer and a picture of Marilyn Monroe wearing one), potato engravings, prints and paintings (one from 16th century Italy, another a copy of "The Potato Eaters" by Vincent Van Gogh), Inca potato artifacts and potato tools. "The tools are hard to find," Hughes says. "People don't want to keep things associated with misery and hardship" derived from the work of harvesting the potato.

"I also collect {examples of} how potatoes are used in nontraditional ways," he said. These include: a small army of Mr. Potato Head toys; a copy of The Spud, the Idaho Falls High School yearbook; a pack of Spud, the first mentholated cigarette, from the 1930s; potato crystals like those used to make the first color photographic slide in 1904; a toy gun that shoots a potato plug; potato paper from Germany; potato jewelry made by a woman in Michigan; and the work of a man who, living in a Manhattan high-rise, got so tired of throwing out all his potato peelings that he started making them into picture frames and bowls.

"I even had some potato ice cream once," Hughes says, but he leaves it at that.

Most of these things have been tracked down by the Hugheses with investigative skills well-honed in a decade of potato digging. Other items in the Potato Museum's collection have been donated by fellow enthusiasts of the spud.

"I had a woman here last week who is the widow of the man who invented potato flakes," Tom Hughes says. "She brought us his picture. She promised me some of his papers."

Tunes such as Al Yankovic's "Addicted to Spuds," Louis Armstrong's "All That Meat and No Potatoes" and The Kinks' "Hot Potatoes" play on a tape deck to set the appropriate mood.

There are also videotapes of how the potato has been portrayed in the movies. In the original Mickey Mouse cartoon, for instance, Mickey is punished, so he has to go to the galley -- to peel potatoes. A 1924 D.W. Griffith film shows Germans, impoverished by World War I, being robbed of their only worldly goods: a wagon of potatoes. In the opening scenes of the German film "The Tin Drum," a peasant hides a fugitive under her skirts in the middle of a potato field.

The video presentation, played on a videocassette recorder, is interrupted by part of a baseball game. "This has nothing to do with potatoes," Hughes informs. He has other interests.

Of course, Hughes hasn't neglected to become a member of the Association of Potato Masher Collectors, the Association of Couch Potatoes or the American Potato Society. "It's definitely a passion," he says.

The passion was kindled in 1973 when Hughes instructed his class at the International School in Brussels to learn more about the potato. But it was the teacher who "started to think about the potato like never before."

What he started to think about, and what his message became, was how something of huge importance to human nutrition, culture and migration for centuries had been virtually ignored, or at least taken for granted.

By 1978, he had quit his job at the school to research the potato full time. The Frito-Lay company hired Hughes for six weeks during 1980-81 to travel around the United States to talk to schoolchildren about the potato. The trips allowed Hughes to gather items for his museum and to vastly increase his knowledge of the potato. The Hugheses moved to Washington in 1983 and opened the museum the next year in their dining room. Their book, "The Great Potato Book," was published in 1986.

Hughes' lore of the spud basically celebrates one fact. "The potato's the world's number one vegetable," he explains.

"It's the fourth-ranking staple," he will concede, but "it cannot be disputed in terms of yield per acre."

The power of the potato in history also cannot be disputed, according to Hughes. The poor of Europe came to rely on the potato after the vegetable was brought back from conquered Inca Peru in the 16th century. The potato famine in Ireland in 1846 decimated that nation and led to the migration of more than a million Irish to America.

Hughes has a special passion for Peru. The International Potato Center, located in Lima, pays the basement rent that enabled Hughes to get the potato museum off his dining room table at the beginning of this year. Hughes makes regular pilgrimages to Peru, where he gathers new information to gird his message about the potato.

"It's pretty misunderstood," Hughes says of the enduring object of his affection. For instance: "People continue to think it's fattening or not nutritious. And frying it -- this is the worst way of eating it."

But Hughes can tell these things to only a "trickle of visitors" for now, mostly journalists and school groups. In recent months, television crews from Idaho and Norway have come to do stories on his museum. Also, he says, potato growers from Mexico traveled to Washington "just for the purpose of seeing the potato museum."