Which type of nut is used in a Waldorf Salad?

A Waldorf salad is a fruit and nut salad generally made of fresh apples, celery, grapes and walnuts, dressed in mayonnaise, and served on a bed of lettuce as an appetizer or a light meal.

The name comes from the fact that the Waldorf salad was first created for a charity ball given in honor of the St. Mary’s Hospital for Children on March 14, 1896 at the Waldorf-Astoria hotel in New York City. Oscar Tschirky, who was the Waldorf's maître d'hôtel, and who developed or inspired many of its signature dishes, is widely credited with creating the recipe. In 1896, the salad appeared in 'The Cook Book' by "Oscar of the Waldorf"

Other ingredients, such as chicken, turkey, and dried fruit (e.g. dates or raisins) are sometimes added. Updated versions of the salad sometimes change the dressing to a seasoned mayonnaise or a yoghurt dressing.