A leaf scale may be either the fine, grainy surface material of the object or a particular type of modified leaf. Red and white cedars are common trees that exhibit the flat, sharply triangular and overlapping leaves, referred to as scales. Bromeliads, however, are a family of plants that exhibit an abundance of scales covering their leaves, which play an important role in water absorption.

Although leaves can vary in shape, size, and function, they generally share the same basic structure, but exhibit various modifications. Typically, a leaf will be composed of a petiole, a blade, and a stipule. The petiole is the leaf stalk and the flat, expanded part of the leaf is known as its blade. Stipules are also flat, but are usually flaps located below the main body of the leaf. Some leaves do not have stipules, but they may be hard to identify even in those that do because stipules are often highly modified into structures such as spines or tendrils.

The majority of leaves are green throughout most of the year, but may change to bright red, yellow, and orange hues in temperate regions during autumn. The sudden change in coloration does not serve a particular function, but is a side effect of chemical changes caused by increasingly shorter periods of daylight. Interestingly, leaves contain the same amount of yellow pigmentation year-round but the lighter color is masked in the summer months by the green of chlorophyll.