Abaxial

In botany, abaxial refers to the surface of a plant organ that faces away from the axis or stem. It is often referred to as the lower surface of a leaf or the outer surface of a petal or sepal. The abaxial surface is typically distinct from the adaxial surface, which faces towards the axis. Differences in texture, color, and the presence of features like hairs (trichomes) or stomata are common between the abaxial and adaxial sides.

The term can also be applied to other plant parts, such as bracts or modified leaves, describing the surface furthest from the point of attachment or the main axis. Understanding the abaxial and adaxial surfaces is important in plant morphology and taxonomy as these surfaces can possess different characteristics that aid in identification and classification. The specific characteristics of the abaxial surface often play a role in the plant's interaction with its environment, influencing factors like transpiration, light capture, and protection from herbivores.