Cultivated annual salad plant ( Lactuca sativa ) that produces clusters of crisp, water-filled leaves.
The best-known varieties are head, or cabbage, lettuce (variety capitata ); leaf, or curled, lettuce (variety crispa ); cos, or romaine, lettuce (variety longifolia ); and asparagus lettuce (variety asparagina ). Head lettuce is further divided into butter heads and crisp heads (e.g., iceberg lettuce). In the U.S, large-scale farms grow mainly crisp-head varieties, shipping them nationwide. Small-scale, local farmers raise leaf and butter-head varieties. Lettuce is an early annual crop that grows best in cool weather and with ample water. Though usually consumed in salads, it may also be cooked.
Lettuce ( Lactuca sativa , variety capitata )
Derek Fell