Grown in the warm, humid tropics, bananas are picked and shipped green; contrary to nature's norm, they are one fruit that develops better flavor when ripened off the bush. Banana bushes mature in about 15 months and produce one 50-pound bunch of bananas apiece. Each bunch includes several "hands" of a dozen or so bananas (fingers). There are hundreds of banana species but the yellow Cavendish is America's favorite. Choose plump, evenly colored yellow bananas flecked with tiny brown specks (a sign of ripeness). Avoid those with blemishes, which usually indicate bruising. Bananas that are still greenish at the tips and along the ridges will need further ripening at home. To ripen, keep uncovered at room temperature (about 70°F). For speedy ripening, enclose bananas in a perforated brown paper bag. Ripe bananas can be stored in the refrigerator for several days. The peel will turn brown but the flesh will remain unchanged. Once exposed to air, a peeled banana will begin to darken. To avoid discoloration, brush with lemon juice or dip in acidulated water. Now available in some markets are the short, chunky red banana and the dwarf or finger banana, both of which are sweeter than the Cavendish, the apple-flavored Manzano (which turns black when ready to eat), the diminutive Mysore from India and the Orinoco with its trace of strawberry flavor. The plantain, a very large, firm variety, is also referred to as a "cooking banana" and is extremely popular in Latin American countries. It has a mild, almost squashlike flavor and is used very much as a potato would be in the United States. Banana leaves are used in the cooking of Mexico, Central and South America, the Caribbean and Southeast Asia to wrap foods for steaming. They can be found in Latin markets. Banana flour is a nutritious and easily digestible powder made from specially selected bananas that have been dried and ground. Bananas are high in carbohydrates and low in protein and fats; they're also rich in potassium and vitamin C.