Spinach
Spinach, common name for an annual crop plant, of the goosefoot family, grown for its nutritious and savory leaves. Probably native to southwestern Asia, spinach was introduced to Europe by the 12th century. It became cultivated worldwide and received sudden popularity in the 1920s when nutritionists found it contained iron, vitamin A, and vitamin B2, or riboflavin. Two varieties of spinach are now grown. Wrinkled, or savoy, spinach can be packaged and shipped without wadding or spoiling and is marketed fresh. Smooth-leaved spinach can be easily washed and is marketed frozen or canned. Spinach leaves are picked from the immature plant when in the form of a rosette close to the ground. Because extended daylight and hot temperature cause the plant to bolt, or draw growth away from the leaves and into a tall, central flower stalk, spinach is best cultivated in cool climates during spring or fall, or in warm climates during winter. Most spinach in the United States is now produced i