(redirected from abscissions)
Also found in: Dictionary, Thesaurus, Medical.
Related to abscissions: abscission layer


The process whereby a plant sheds one of its parts. Leaves, flowers, seeds, and fruits are parts commonly abscised. Almost any plant part, from very small buds and bracts to branches several inches in diameter, may be abscised by some species. However, other species, including many annual plants, may show little abscission, especially of leaves.

Abscission may be of value to the plant in several ways. It can be a process of self-pruning, removing injured, diseased, or senescent parts. It permits the dispersal of seeds and other reproductive structures. It facilitates the recycling of mineral nutrients to the soil. It functions to maintain homeostasis in the plant, keeping in balance leaves and roots, and vegetative and reproductive parts.

In most plants the process of abscission is restricted to an abscission zone at the base of an organ (see illustration); here separation is brought about by the disintegration of the walls of a special layer of cells, the separation layer. The portion of the abscission zone which remains on the plant commonly develops into a corky protective layer that becomes continuous with the cork of the stem.

Diagrams of the abscission zone of a leafenlarge picture
Diagrams of the abscission zone of a leaf

Auxin applied experimentally to the distal (organ) side of an abscission zone retards abscission, while auxin applied to the proximal (stem) side accelerates abscission. The gibberellins are growth hormones which influence abscission. When applied to young fruits or to leaves, they tend to promote growth, delay maturation, and thereby indirectly prevent or delay abscission. Abscisic acid has the ability to promote abscission and senescence and to retard growth. Small amounts of ethylene have profound effects on the growth of plants and can distort and reduce growth and promote senescence and abscission.

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.


A physiological process promoted by abscisic acid whereby plants shed a part, such as a leaf, flower, seed, or fruit.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The high positive correlation between flowers and harvestable pods on one hand and between seed yield and the number of flowers, harvestable pods, weight per seed and seeds per pod on the other, suggests that abscission of reproductive organs could reduce seed yield.
This study has shown that reproductive abscission exists in mungbean.
[5.] Izquierdo JA and GL Hosfield A Collection Receptacle for Field Abscission Studies in Common Bean.
[7.] Subhadrabandhu S, Adams MN and DA Reicosky Abscission of Flowers and Fruits in Phaseolus vulgaris L.
[8.] Ojehomon OO Fruit Abscission in Cowpea, Vigna unguiculata (L.) Walp.
[9.] Kureh I, Gupta US and OO Olufajo Cultivar and Plant Density Effects on Floral Abscission and Seed Yield of Soybean in a Sub-humid Environment.