Instructions: Their flavor has been described as pungent, trufflelike, earthy, bold. But cookbook author Marion Cunningham may have captured the flavor of black walnuts best when she called it haunting.

These curious-looking, shaggy brown nuts evoke vivid memories. Just ask Sally Oliver of Cache Creek Farms, who sells the rare nuts at the Ferry Plaza Farmers Market in San Francisco only in December.

Since I began selling black walnuts, Ive heard so many childhood stories Ive been tempted to compile them into a book, she says. Among her favorites is a customers tender remembrance of her mothers black walnut cake, hidden in a dresser every year so her family wouldnt eat it before Christmas.

Black walnuts are proud North American natives, unlike the milder-flavored English walnuts most of us know from the grocery store. Several species of the nut are found throughout the United States, including the Eastern black walnut (Juglans nigra) and the Northern California black walnut (Juglans hindsii). The once thriving black walnut processing industry, which involves hulling, shelling and packaging the nuts, has dwindled over the past few decades to only a handful of companies.

Yet, with demand now exceeding supply, there appears to be growing interest in the nut.

Black walnuts fit with todays food trends, says Brian Hammons, president of Hammons Products in Stockton, Mo., the only remaining commercial processor of the Eastern black in the world. Chefs like them because theyre a regional, historical ingredient with a unique flavor. Home bakers love them, especially during the holidays. And for many people they are a comfort food they associate with their grandmother.

The Northern California black walnut - trees grow in Morgan Hill and Gilroy as well as the Central Valley, Chico and Sonoma areas - is in shorter supply than its Eastern counterpart. With its milder flavor, it has a reputation as a better snacking nut. Professional chefs often prefer the Eastern variety for cooking and baking because of its deeper, wilder flavor.

Geological evidence dates black walnut trees to the Pleistocene era. Native Americans were dining on them as long as 2,000 years ago, eating them raw, in nut butters and milks, and as a seasoning in pumpkin soups. They shared their knowledge of the trees with newly arriving European colonists, but the settlers were soon felling the trees to make guns and furniture. Black walnut still ranks as one of the most valuable single species of hardwood.

Aside from their distinctive flavor, striking appearance and reputation as the most difficult nut to crack, another thing that sets black walnuts apart is that they are a wild nut, unlike English walnuts, almonds and other tree nuts that are grown in vast commercial orchards.

As Jim Jones, director of the Center for Advancement of American Black Walnut, a non-profit research organization in Missouri, explains, Ninety-nine point nine percent of the black walnuts gathered this fall come from wild trees that have been planted by squirrels.

The harvesting of black walnuts also differs dramatically from that of the U.S. commercial nut industry, a large segment of which is centered in California. While commercial growers use mechanical shakers to remove nuts, black walnuts are gathered by hand from back yards, pastures, fields and creek beds after autumns first blustery winds and rains cause ripe nuts to drop from the tree.

The Northern California black walnut tree used to be a far more common sight.

During the Depression, the Works Progress Administration gave people jobs planting them along two-lane highways throughout Northern California, boosting the number of feral trees. But the population has declined since then.

Weve lost black walnut trees to housing developments and the expansion to multi-lane freeways, observes Virgil Suess, vice president of Lodi Nut Co. in Lodi. Many have been cut down, and because of the high price of the lumber, there have been problems with tree `rustling.

Back in 1949, when Lodi Nut was founded, black walnut processing represented 100 percent of its business and the company had numerous competitors. Now, black walnuts make up just 5 percent of the business, and to Suess knowledge, Lodi Nut is the largest remaining processor in Northern California.

The company collects and processes black walnuts sold by Diamond of California and provides nuts to Safeway for its house brand of black walnut ice cream. Still, Suess says, sadly, I believe its a dying business in California.

The future looks brighter for the Eastern black walnut, according to Hammons.

Hammons Products and the Center for Advancement of American Black Walnut are researching methods to increase the number of trees. Both envision a future when orchards will supplement the wild supply.

This fall, Hammons purchased about 38 million pounds of Eastern blacks from a 13-state area, a minuscule amount compared to the expected 560 million pounds of English walnuts from California.

They are a true delicacy, says Hammons.

They are also nearly twice the price of English walnuts, but a smaller quantity is needed in recipes because of their pronounced flavor.

In American Cookery, James Beard recommends browning black walnuts in butter and serving them over cooked cauliflower.

Or roast a handful and add them to a green salad.

Lindsey Shere, author of Chez Panisse Desserts and former pastry chef at the restaurant, has long used wild nuts in her cooking.

When she worked at Chez Panisse, her father would gather black walnuts from trees growing along the Russian River and bring them to the restaurant. Shere made black walnut ice cream and sometimes added the finely chopped nuts to crepe batters.

Pear ice cream is lovely with black walnut crepes, Shere says. Maple ice cream would be good, too, as the flavor of the nuts is reminiscent of maple.

Black walnuts deserve a starring role in any home bakers pantry. They make glorious cakes, cookies and pies and are a fragrant addition to banana, pumpkin and zucchini breads. They are incomparable in candies such as brittle, toffee and fudge. Or perhaps, like so many others, you have a favorite black walnut memory from childhood. For me, its my grandmothers black walnut spice cake, rich with the haunting flavor of one of the countrys splendid wild foods.

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