The fruit of various members of the gourd family native to the Western Hemisphere. There is evidence of squash being eaten in Mexico as far back as 5500 B.C., and in South America over 2,000 years ago. Squash varies widely in size, shape and color. Generally, they're divided into two categories-summer squash and winter squash. Summer squash have thin, edible skins and soft seeds. The tender flesh has a high water content, a mild flavor and doesn't require long cooking. The most widely available varieties of summer squash are CROOKNECK, PATTYPAN and ZUCCHINI. Summer squash is best from early through late summer, although some varieties are available year-round in certain regions. Select the smaller specimens with bright-colored skin free of spots and bruises. Summer squash is very perishable and should be refrigerated in a plastic bag for no more than 5 days. It can be prepared by a variety of methods including steaming, baking, sautéing and deep-frying. Summer squash are high in vitamins A and C as well as niacin. Winter squash have hard, thick skins and seeds. The deep yellow to orange flesh is firmer than that of summer squash and therefore requires longer cooking. Winter squash varieties include acorn squash, BUTTERCUP, butternut squash, HUBBARD, spaghetti squash and TURBAN. Though most varieties are available year-round, winter squash is best from early fall through the winter. Choose squash that are heavy for their size and have a hard, deep-colored rind free of blemishes or moldy spots. The hard skin of a winter squash protects the flesh and allows it to be stored longer than summer squash. It does not require refrigeration and can be kept in a cool, dark place for a month or more, depending on the variety. Once the seeds are removed, winter squash can be baked, steamed or simmered. They're a good source of iron, riboflavin and vitamins A (more than summer squash) and C. See also CALABAZA; CUSHAW; DELICATA; GOLDEN NUGGET; KABOCHA; PUMPKIN; VEGETABLE MARROW; SQUASH BLOSSOMS.