There are many different varieties of this mustard-family plant, the most popular of which is watercress. Other types include peppergrass (also called curly cress), broadleaf cress (also called cressida) and garden cress. All cress varieties share a peppery tang. Choose cress with dark green leaves and no sign of yellowing. Refrigerate in a plastic bag (or stems-down in a glass of water covered with a plastic bag) for up to 5 days. Cress is used in salads, sandwiches, soups and as a garnish.