 Lettuce is the only member of the Lactuca genus to be grown commercially . The Food and Agriculture Organization of the United Nations ( FAO ) reports that world production of lettuce and chicory ( the two crops are combined by the FAO for reporting purposes ) for calendar year 2010 was 23 @,@ 622 @,@ 366 metric tons ( 23 @,@ 249 @,@ 287 long tons ; 26 @,@ 039 @,@ 201 short tons ) . This came primarily from China ( 53 percent ) , the US ( 17 percent ) and India ( 4 percent ) . Although China is the top world producer of lettuce , the majority of the crop is consumed domestically . Spain is the world 's largest exporter of lettuce , with the US ranking second . 
