The Plant Mustard Family is a group of flowering plants that includes the species cress (5 letters). Cress is an edible plant that is often used in salads and sandwiches. It is known for its peppery flavor and is a popular garnish. The Plant Mustard Family also includes other species such as watercress, horseradish, and mustard greens. These plants are all related and have similar characteristics, such as their pungent flavor and their ability to grow quickly.