Lettuce

Cultivated lettuce, Lactuca sativa, is generally understood to descend primarily from prickly lettuce, Lactuca serriola, a wild species native across parts of Southwest Asia, North Africa, and the Mediterranean region. Because domestication occurred over a broad, interconnected area, lettuce has no single uncontested birthplace.

Early evidence points especially to ancient Egypt, where lettuce was depicted and cultivated thousands of years ago. The earliest managed plants may have been valued partly for oil-rich seeds or medicinal latex rather than for mild leaves. Farmers gradually selected less prickly, less bitter plants with larger leaves and stems that were slower to flower.

Lettuce spread through the Greek and Roman worlds and later across Europe, where growers developed increasingly distinct forms. Centuries of selection produced the major groups now recognized in markets: loose-leaf, romaine or cos, butterhead, crisphead, and stem lettuce.

Today lettuce is cultivated worldwide in cool seasons and mild climates. California and Arizona dominate commercial production in the United States, with major districts shifting by season between coastal valleys and warmer desert regions. Its modern global identity is therefore much broader than its ancient center of domestication.