Which spice is often added to the American dessert Apple Crisp?

Apple crisp is a dessert made with a streusel topping. In the US and Canada, it is also called apple crumble, a word that refers to a different dessert in the UK, Australia, and New Zealand. Ingredients usually include cooked apples, butter, sugar, flour, cinnamon, and often oats and brown sugar, ginger, and/or nutmeg. One of the most common variants is apple rhubarb crisp, in which the rhubarb provides a tart contrast to the apples.

Source: Wikipedia