Banana leaves
Large, pliable leaves of the banana plant used to wrap food for steaming, baking or braising; they lend a mild, grassy aroma and are not eaten.
Banana leaves are usually sold frozen, less often fresh, in Asian grocers or shops for Latin American and African foods, and by mail order. Warm them briefly over a flame or in hot water before wrapping so they turn supple and do not tear.
Substitute:
Parchment paper covered with a layer of foil holds juices and moisture in about as well, but the faintly grassy, tea-like aroma of the leaves is lost; for tamales, dried corn husks also work, though they taste different and make smaller parcels.