Nothing seems more typical of Napa Valley this time of year than all those beautiful mustard flowers, but in truth, they’re no more native than the grape vines. Both came from Europe, the vines mostly legal immigrants, the mustard illegal.

Legend says that Padre Junipero Serra planted the mustard as a way to mark the way between the missions, but if he did, he must not have known how prolific the plant is; now the state is a sea of mustard, not a path.

More likely, the tiny seeds were accidental travelers, hidden in bedding or the fur of cattle and sheep, says Prof. Andrew Walker at the University of California at Davis.

The plants, which are members of the cabbage family, now provide cover crops in many vineyards, helping prevent erosion during the wet winter and spring. They also provide useful soil amendment. Though some growers plant mustard, it seeds itself so readily that they don’t generally need to. The plants are plowed under when the frosts arrive so the Sun can heat the soil.

Many varieties of mustard can be found in the Valley. The primary varieties are Brassica nigra and B. campestris, though some I picked seem to be field mustard (B. rapa), identified by distinctive upper leaves that clasp the long stem like ears. It sure looks and tastes like Italian rapini or cime di rapa, greens from a turnip that doesn’t form a bulb. Cime is often confused with broccoli rabe, which is not broccoli either but is very tasty. I also found some more classic mustard greens without a stalk. They all have a hot slightly bitter flavor that is tamed somewhat by brief cooking.

These wild varieties are closely related to cultivated mustard (B. japonica) and turnip greens Southerners like me eat, as well as the Italian greens. They are edible, though make sure they’re not from fields recently sprayed with herbicides or pesticides before you collect them! Fortunately most Valley growers use few chemicals. Rinse well in case any dogs passed by, too.

The small young leaves are tender and delicate, providing a refreshing bite to salads and sandwiches much like arugula. The larger leaves can be cooked like any green by boiling, steaming and stir-frying. The unopened buds are tasty, too. The greens are excellent sources of vitamins A and C, and have anticancer properties.

The raw flowers make a nice edible garnish for green or white foods.

The mustard seeds can be ground, then pressed and dried to produce dry mustard, a fiery paste, or prepared in many other ways. Commercial brown and Dijon mustard is mostly from B. nigra or a slightly milder version, B. juncea (East Indian mustard), whereas wimpy American French’s ballpark mustard is from Sinapsis alba or white mustard with yellow turmeric coloring.

Here are few ways to prepare the greens. You can obviously use mustard or turnip greens from your local grocery or garden, too.

Southern-Italian Style Mustard Greens

Heat a teaspoon of fragrant extra-virgin olive oil in a hot skillet. Add sliced garlic and sauté for a minute or so, not letting it brown. Wash the greens well, then without drying, throw in the pan, cover and let steam-sauté for a few minutes. Depending on the greens, they typically cook in a couple of minutes. Salt and serve hot, perhaps with some grated Parmesan cheese. With a little broth or extra oil, this also makes a good pasta sauce, traditionally served with orecchietti (little ears).

Risotto with Mustard Greens and Goat Cheese

A rich risotto and goat cheese help balance the peppery bitterness of mustard greens.

Blanche greens, refresh in cold water, drain and chop.

Prepare basic risotto using onion or leeks, garlic and olive oil plus beef stock.

When rice is done, add greens and a small amount of goat cheese
(about 1 tablespoon per 1½ cup of raw rice, enough for four people). Garnish
with mustard flowers.

Traditional Southern Greens

Boil greens uncovered for 40 minutes with ham bone or ham hock. Serve with pot "likker," (reduced stock), hot sauce and cornbread. Great with roasted possum or 'coon or fried squirrel and grits.