THE CENTERPIECE of the Passover meal, the prime feast of the Jewish liturgical year, is a hairy, ugly root, the horseradish. Known as moror, or the bitter herb, it stands for the harshness of slavery; a taste of it is obligatory. But today's Israelites sandwich the grated horseradish with chopped apple and nuts when they put it between two pieces of matzoh, so the tears are fewer.

Overpowering in its fiery taste, indestructible as a plant, persistent in any type of soil, the horseradish is a bravura herb. Compared to the lyric thyme and the subtle cinnamon, the horseradish is an expletive. Some enthusiasts recommend a teaspoon of it every day, particularly during winter, to keep sinuses free and clear.

The horseradish is one herb that thrives in the coldest winter and is unfazed by neglect. Its flavor is the freshest in early spring when the vegetable garden has nothing else to offer. But it can be dug up at any time of the year.

It is a scraggly root the color of earth. Its thickened mother root looks like a misshaped turnip or the mysterious mandrake root.

Its pungency has one pitch. There is no variation, no hint of sweetness, no compromise. To civilize its taste, the French soak it in olive oil or heavy cream, dilute it with mayonnaise or white wine. Central Europeans eat it freshly grated as a garnish to frankfurters or boiled beef--a counterpoint to mere meat. Pickled, minced or finely ground, it is responsible for the hottest mustards and the spiciest sauces to correct oily fish and fat viands. It adds zest to a bloody mary, and it figures in cures for a hangover.

The horseradish foliage is as luxuriant as a tropical plant's. Bunches of three-foot-long, four-inch-wide leaves issue from the crown of the root. Their color is an inviting dark green, but their taste is discouragingly bitter.

The horseradish plant has a network of roots as thick as a pencil and as long as three feet, always spreading. It is a conspiracy. The more roots you snip off, the more bulbous mother roots will develop, which in turn send out more lateral roots. When attacked by the spade, the roots escape as deep as six feet underground.

Once you plant it, you can't get rid of it and you'll always have more of it than you need. A part of a bulbous root tossed into the yard after the Passover meal will yield a patch in two years. "Rampant" is what herb books call its habit of growth--a heraldic term as refined as "piquant" is in reference to its taste.

A prudent gardener is well advised to confine it to a remote corner of the yard and to keep a wary eye on its new shoots. But a prudent gardener is almost as rare as non-rampant horseradish. In the absence of both, what one needs is recipes to absorb the overabundance. For a start:

HORSERADISH SAUCE FOR BEEF (6 servings) 1 large horseradish root, peeled and grated 1 medium-size potato, boiled and grated 1 tablespoon vinegar 3 tablespoons olive oil Salt to taste

Combine all ingredients and serve.

HORSERADISH SAUCE FOR FISH (6 servings) 6 apples, cored, peeled and grated 2 tablespoons sugar 1 cup white wine 1/2 cup wine vinegar 1 medium horseradish root, peeled and grated

In a saucepan combine apples, sugar and enough water to barely cover. Cook until apples are very soft. Add wine, vinegar and horseradish root and cook about 10 minutes, or until thick.

HORSERADISH RELISH FOR MEAT DISHES (2 to 4 servings) 1 bunch red beets 1 horseradish root, peeled and grated finely 1/2 cup apple cider vinegar

Cook the beets, then drain, peel and slice. Combine grated horseradish root and vinegar and mix into the beets. Keep covered. This keeps for several weeks in the refrigerator.