Lactuca sativa L. var. longifolia
Romaine or Cos lettuce (often called simply Roman or Cos) is a variety of lettuce which grows in a long head and having a robust leaves, long and with a robust midrib. Unlike other lettuce is more tolerant to heat.
Its flavor is slightly bitter, making it one of the most used lettuce salads. The Roman is used in Caesar salad. Romaine lettuce is used in the celebration of Passover and is a kind of bitter herb that symbolizes the bitterness of the Jews being enslaved in ancient Egypt.