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A leaf scar is the mark left by a 
leaf
A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leav ...
after it falls off the twig. It marks the site where the petiole
Petiole may refer to:
*Petiole (botany), the stalk of a leaf, attaching the blade to the stem
*Petiole (insect anatomy)
In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, and ...
attached to the stem
Stem or STEM most commonly refers to:
* Plant stem, a structural axis of a vascular plant
* Stem group
* Science, technology, engineering, and mathematics
Stem or STEM can also refer to:
Language and writing
* Word stem, part of a word respon ...
. A leaf scar is typically found below a branch, as branches come from axillary bud
The axillary bud (or lateral bud) is an Plant embryogenesis, embryonic or Organogenesis#Plant organogenesis, organogenic Shoot (botany), shoot located in the axil of a leaf. Each bud has the potential to form shoots, and may be specialized in prod ...
s located above leaf scars.
Formation
Leaf scars are formed naturally, often at the end of the growing season fordeciduous
In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...
plants when a layer of cells called the abscissa layer forms between the petiole and stem. The abscission
Abscission () is the shedding of various parts of an organism, such as a plant dropping a leaf, fruit, flower, or seed. In zoology, abscission is the intentional shedding of a body part, such as the shedding of a claw, husk, or the autotomy of a ...
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. Stipule
In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole (botany), petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part ...
s may also leave their own scars if they are present.
Bundle scars
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. The number of bundle scars in a leaf scar is sometimes used as an identifying mark as they are often consistent across a species.
See also
*Scar
A scar (or scar tissue) is an area of fibrosis, fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other Organ (anatomy), organs, and biological tissue, t ...
* Scarred tree
A scarred tree or scar tree, also known as a canoe tree and shield tree, is a tree which has had Bark (botany), bark removed by Aboriginal Australians for the creation of Canoe#Australia, bark canoes, humpy, shelters, weapons such as shields, to ...
References
Plant morphology {{plant-morphology-stub