Romaine lettuce has sturdy green leaves about 10" long and grows in tall fairly compact heads. You can purchase romaine head whole or trimmed into romaine hearts. The small inner leaves can be used as wrappers. The hearts can be sliced in half lengthwise and topped with Caesar dressing and Parmesan cheese for a classic Caesar Salad.
The salad shown combines romaine lettuce with citrus fruits, pomegranate seeds and olives.
If you don't have romaine lettuce or you're seeking an alternative due to the recent e Coli outbreak, here are some alternatives:
You can use Iceberg lettuce which is less flavor but crisp like romaine.
OR> Use butter head lettuce (Bibb or Boston) which is softer but flavorful
OR> Leaf lettuce like oak or Lollo rosso.
OR> For a green with a little bite, but firm leaves try curly endive. I've used this in a Caesar salad and it was very good. You may want to combine with another lettuce like butter lettuce, the leaves are soft but they are sturdy enough to hold up to a dressing like Caesar.