Vegetables are usually classified on the basis of the part of the plant that is used for food.
The Root vegetables include beets, carrots, radishes, sweet potatoes, and turnips.
The Stem vegetables include asparagus and kohlrabi. Among the edible tubers, or underground stems, are potatoes.
The leaf and leafstalk vegetables include cabbage, celery, lettuce, rhubarb, and spinach.
The bulb vegetables are garlic, leeks, and onions.
The head, or flower, vegetables include artichokes, broccoli, and cauliflower.
The Seed vegetables are usually legumes, such as peas and beans.
The fruits commonly considered vegetables by virtue of their use include cucumbers, eggplant, okra, sweet corn, squash, peppers, and tomatoes.
Vegetables may be washed, sorted, graded, cut, and packaged for sale as fresh products. Fresh vegetables are subject to quick aging and spoilage, but their storage life can be extended by such preservation processes
as dehydration, canning, freezing, fermenting, or pickling.