A leaf scar is the mark left by a leaf after it falls off the twig. It marks the site where the petiole attached to the stem. A leaf scar is typically found below a branch, as branches come from axillary buds located above leaf scars.
Leaf scars are formed naturally, often at the end of the growing season for deciduous plants when a layer of cells called the abscissa layer forms between the petiole and stem. The abscission layer acts as a point of cleavage and the leaf breaks off leaving a cleanly shaped wound that is quickly healed over with protective cork. Stipules may also leave their own scars if they are present.[1]
Bundle scars are circular or barred regions within the leaf scar where bundles of vascular tissue that had connected the leaf and the stem broke off.[2] The number of bundle scars in a leaf scar is sometimes used as an identifying mark as they are often consistent across a species.