Salad leaves are typically green and leafy, and can come from a variety of plants. Common salad greens include lettuce, arugula, spinach, and kale. These leaves are all relatively soft and easy to chew, making them good choices for salads. There are also many other types of leaves that can be used in salads, such as cabbage, endive, and radicchio. These leaves may be harder to chew or have a more bitter flavor, but can still add interesting texture and flavor to a salad.