In zoology, abscission is the intentional shedding of a body part, such as the shedding of a claw, husk, or the autotomy of a tail to evade a predator. In mycology, it is the liberation of a fungal spore. Define abscission : the act or process of cutting off : removal.

In botany, abscission is the normal separation of a plant part or organ. Abscission , a physiologically determined program of cell separation . It occurs to separate a plant part or organ that may no longer be necessary.

For instance, leaf abscission is the normal shedding of an old leaf at the base of the petiole such as that occurs during autumn. Delta Journal by Bob Thomas. Why do leaves fall off plants and how does it happen? First, all plants shed their leaves. In leaf …of a weak zone, the abscission layer, at the base of the petiole.

Their normal formation in autumn appears to be, in part at least, due to the shortening of the day. Perhaps the shorter days . Meaning, pronunciation, translations and examples. Every year we see trees drop their leaves in anticipation of winter.

This actually has a specific purpose and reason. In the process of leaf abscission , plants periodically shed their leaves. Leaf abscission involves a number of biochemical and physical changes that are largely controlled by plant hormones.

Plants are primarily categorized as annuals , biennials, or perennials, based on their growth patterns. Annuals are those plants that . The abscission rates can be evaluated by counting the percentage of telophase cells that have clearly established an abscission site, as determined by the presence of a gap in the central spindle. Care must be taken not to count a midbody-associated gap.

Similarly, abscission sites can be counted by determining the . Ethylene has been generally credited with promoting the abscission of the oldest leaves on a plant first. Vegetative cotton (Gossypium hirsutum L.) seedlings are an exception to this generalization. Under some conditions the younger, apical, unexpande or partially expanded leaves abscise before the less young, . The leaf blade of cotton (Gossypium hirsutum L. cv.

Stoneville 213) was investigated as the initial site of ethylene action in abscission. However, keeping only the leaf blade of this leaf in air during ethylene . There is a large body of evidence which correlates the development of some phases of senescence with the ability of petioles to experience abscission. We have suggested that the change-over from stage to stage in the aging of bean petiole explants may be a reflection of initial stages of senescence in the pulvinar. Evidence supporting the hypothesis that ethylene is involved in the control of senescence and abscission is reviewed. The data indicate that ethylene causes abscission in vivo by inhibiting auxin synthesis and transport or enhancing auxin destruction, thus lowering the diffusible auxin level.

Studies with isolated leaves and . Definition of abscission – the natural detachment of parts of a plant, typically dead leaves and ripe fruit.

English dictionary definition of abscission. Botany The shedding of leaves, flowers, or fruits following the formation of the abscission zone. All leaves have a definite life span and are dropped following receipt of internal or environmental signals.

The process is termed abscission and is facilitated. Synonyms for abscission at Thesaurus. Dictionary and Word of the Day.