Just about the first green shoots to thrust above the ground in early spring are the leaves of the horseradish, while several weeks after, its cousins watercress and land cress provide those who grow them with their earliest garden-fresh salads.

Both horseradish and cress are members of the mustard family, distingished among other things by the pungent oils which permeate their leaves and roots and give the strong, distinctive flavors that provide such wonderful condiments for the table.

When I was a small child I remember going with my grandfather out to the back of his little row house in the old part of the District to seel how the horseradish was doing in his garden. He grew it faithfully every year so that it could accompany the traditional gefilte fish his wife made for the Sabbath and holidays. Old-timers in town still recall purchasing grated horseradish from a gentleman who specialized in providing it - along with barrles of cooked hominy - at the old Central Market, which no longer exists.

Horseradish does not make seeds and must be planted by root cuttings, but it is a perennial so once set in the ground, it is available forever. Introduced into this country in the 1880s from Europe, horseradish is frequently found growing around the foundations of old houses out in the country.Years ago it was valued for medicinal purposes, its leaves applied in a poultice for rheumatism, toothache and neuralgia. It is high in Vitamin C.

Horseradish root looks like an old dog bone. It is simply stuck in the ground and covered with a few inches of earth. If you wish to grow several plants, buy a root with several crowns at the top end. Cut off each of these little crowns along with a wedge of the main root and plant one foot apart. Although the root will start to grow immediately, the pungent flavor will need to develop all spring and summer and reach its peak in the fall, at which time it should be harvested for use. It can be harvested through the winter.

An old garden book of the 19th century suggests that horseradish is grown and harvested to "tickle the jaded appetites of the overfed." Yet at that time, horseradish was a condiment for the poorest peasants of Europe.

Two tablespoons of horseradish mixed with 1/2 pint of whipped cream is delicious with smoked salmon, or boiled beef.

An unusual canape is made by spreading thin slices of black bread with butter to which mustard and chopped chives have been added. This is covered by grated horseradish and then with chopped, hard-cooked egg.

Vinegar preserves horseradish for longer use. But cider vinegar will turn it dark. The addition of grated beets modifies the tartness of the condiment and sweetens it. Mixed with sour cream this last combination is delicious on pickled beets.

One note of caution: Grating horseradish is best done on a breezy day outside, since the fiery vapors it exudes are far stronger on the eyes than those of chopped onion. It is because horseradish can make you cry that it has been used by Jewish people for centuries at the Passover Seder as a reminder of the tears shed during slavery in Egypt.

Horseradish root can be purchased in early spring at Behnke's in Beltsville, at the Southern States Cooperative in Gaithersburg and at Capper's Nursery in Northern Virginia.

I first discovered the simplicity of growing cress while visiting a nearby farm in Virginia. The farmer's wife invited me to go down to the tiny water hole in the pasture and help myself to as much watercress as I wanted for salad that night. I found the delectable grass growing in low-lying masses at the edge of the spring-fed pond and discovered later that it is frequently found locally wherever springs flow out of the earth.

Upland cress is almost identical in taste to watercress, but does not need the wet feet of its cousin and therefore is far more widely grown in this area. Frequently called peppergrass, land cress is planted by seed in earliest spring and virtually springs up out of the soil, ready to consume within three weeks.

Watercress grows easily in this area as long as it is close to fresh-water spring so that the temperature of the water is about 57 degrees. If you have such a spring near you, you may purchase watercress by the bunch at the Three Springs Fisheries in Lilypons, Md., 6 bunches for $5.95.

Seeds for several varieties of land cress can be found at most garden departments and in seed catalogs.

For most people, land cress is the more viable alternative. One devotee sows it mixed with turnip and kale seeds to provide a mixed salad all summer, fall and through much of the winter.

Cress in a salad by itself or with other greens is enhanced by a simple oil and vinegar dressing to which a few drops of honey have been added.

Chopped and heated with cream and butter, nothing is better than cress as an accompaniment to roast chicken.

Here are an unusual cress salad and a simple cress soup. CRESS SALAD WITH HAZEL NUTS (Serves 3 or 4) 1 large bunch cress 1/2 cup coarsely chopped hazel nuts 4 tablespoons grapefruit juice 4 tablespoons oil Salt and pepper to taste

Trim tough ends from cress and wash cress. Put in salad bowl with nuts. Combine grapefruit juice and oil, salt and pepper. Mix well and pour over salad before serving. CRESS SOUP (Serves 4 or 5) 3 to 4 medium potatoes 2 cups scalded milk 1 large bunch cress 4 tablespoons butter 4 teaspoons parsley or chervil Salt and pepper to taste

Peel potatoes and cut in pieces. Boil until soft in water to cover. Mash in pan (do not drain). Add milk and as much water as needed to get a good soup consistency. Season with salt and pepper. Wash, trim and chop cress and add to soup. Cook for 5 minutes.Just before serving, add parsley or chervil. Season with salt and pepper. Good hot or cold.