The tomatillo (Physalis philadelphica) is a plant of the Solanaceae (nightshade) family, related to tomatoes, bearing small, spherical and green or green-purple fruit of the same name. Tomatillos, referred to as green tomato (Spanish: tomate verde) in Mexico, are a staple in Mexican cuisine. Tomatillos are grown throughout the Western Hemisphere The tomatillo fruit is surrounded by a paper-like husk formed from the calyx. As the fruit matures, it fills the husk and can split it open by harvest. The husk turns brown, and the fruit can be any of a number of colors when ripe, including yellow, red, green, or even purple. Tomatillos are the key ingredient in fresh and cooked Latin American green sauces. The freshness and greenness of the husk are quality criteria. Fruit should be firm and bright green, as the green colour and tart flavour are the main culinary contributions of the fruit. Other parts of the tomatillo plant contain toxins, and should not be eaten. Tomatillo plants are highly self-incompatible (two or more plants are needed for proper pollination; thus isolated tomatillo plants rarely set fruit). Fresh ripe tomatillos will keep in the refrigerator for about two weeks. They will keep even longer if the husks are removed and the fruits are placed in sealed plastic bags stored in the refrigerator. They may also be frozen whole or sliced. Organic food is produced by farmers who emphasize the use of renewable resources and the conservation of soil and water to enhance environmental quality for future generations. Organic meat, poultry, eggs, and dairy products come from animals that are given no antibiotics or growth hormones. Organic food is produced without using most conventional pesticides; fertilizers made with synthetic ingredients or sewage sludge; bioengineering; or ionizing radiation. Before a product can be labeled "organic," a Government-approved certifier inspects the farm where the food is grown to make sure the farmer is following all the rules necessary to meet USDA organic standards. Companies that handle or process organic food before it gets to your local supermarket or restaurant must be certified.