/let"is/, n.1. a cultivated plant, Lactuca sativa, occurring in many varieties and having succulent leaves used for salads.2. any species of Lactuca.3. Slang. U.S. dollar bills; greenbacks.[1250-1300; 1925-30 for def. 3; ME letuse, appar. < OF laitues, pl. of laitue < L lactuca a lettuce, perh. deriv. of lac, s. lact- milk, with termination as in eruca ROCKET2 (or by assoc. with Gk galaktoûchos having milk)]
* * *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
* * *▪ plant(Lactuca sativa), cultivated annual salad plant, probably derived from the prickly lettuce (L. scariola) of the family Asteraceae. Four botanical varieties of lettuce are cultivated: (1) asparagus lettuce (variety asparagina), with narrow leaves and a thick, succulent, edible stem; (2) head, or cabbage, lettuce (variety capitata), with the leaves folded into a compact head; (3) leaf, or curled, lettuce (variety crispa), with a rosette of leaves that are curled, finely cut, smooth-edged or oak-leaved in shape; and (4) cos, or romaine, lettuce (variety longifolia), with smooth leaves that form a tall, oblong, loose head. There are two classes of head lettuce: the butter-head types with soft heads of thick, oily leaves, and crisp-head types with brittle-textured leaves that form very hard heads under proper temperature conditions.For successful cultivation lettuce requires ample water, especially in warmer weather. During unseasonable weather, protection is furnished and growth stimulated with greenhouses, frames, cloches, or polyethylene covers. In many parts of the world the leaf and butter-head types are most popular. They are not suitable for shipping, so they are usually grown on truck farms or market gardens relatively close to markets. The crisp-head varieties, well adapted for long-distance shipment, are dominant in the U.S., where over five-sixths of the acreage is located in California and Arizona. In Great Britain cabbage and cos types dominate. Although most commonly consumed in salads, lettuce may also be served as a cooked vegetable.
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