CHAPTER XV 



TRANSPLANTED CROPS THAT MATURE BEFORE THE 

 HEAT OF SUMMER 



HEAD LETTUCE 



In head lettuce the leaves fold over one another, forming a 

 more or less compact head somewhat resembling a cabbage in 

 structure (Fig. 63). The interior leaves are perfectly blanched 

 and the flavor is much more delicate than that of leaf lettuce. 



ction, showing structure. 



Although head lettuce can be successfully grown in cool 

 climates from seed sown in the open ground, the cool season in 

 central latitudes is usually so short that the lettuce is likely to 

 be unable to complete its growth before the advent of hot weather. 

 If overtaken by hot weather rather early in its development the 

 lettuce may fail to form any heads w^hatever. If the hot weather 

 arrives after the heads have started to form the injury may con- 

 sist in a browning of the edges of the leaves that compose the head 

 (sometimes called '' tip-burn ") and the development of a bitter 

 taste. In either case the product is of little value. It is only 

 when the season remains cool and wet unusually late that a satis- 

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