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Flowering  [ Botany - Physiology ]

Dictionary of botanic terminology - index of names

Synonyms: Blossoming, Blooming, To set flowers, to flourish
  Flowering or blossoming is the developmental process of budding and opening of flowers, The state of expansion in a flower; culminating with anthesis when dispersal of pollen and pollination occurs.  
The transition to flower initiation necessitate  the vegetative meristem (buds) to change into a reproductive meristem. This process, which is termed evocation, involves the following sequence of events:

Juvenile vegetative phase  ► Adult vegetative phase  ►  Adult reproductive phase ►  flowering

Juvenile plants are not able to produce flowers; they are capable of only vegetative growth. As a consequence the capability to reproduce is a sign of the transition from the juvenile phase to adulthood.
Juvenile plants often differ in appearance from the adult ( See: primary and secondary sexual characteristic). Juvenile tissues are produced first, near the base of the plant. The adult phase is usually stable and can be propagated from plant to plant.
Differently a mature plant can flower and is said to be "ripe-to-respond (or flower)" or "competent". That is, it has the potential to flower when the conditions are suitable. The process of flowering depend upon a complex ensemble of environmental factors (e.g. photoperiod, temperaturewater availability, etc.) internal factors  (e.g. hormon balance, nutrient levels, health, age, etc.) with correlative influences from various organs (e.g. mechanism that to insure that there is a sufficient vegetative mass and stored reservoir  to support the reproductive output).
Floral induction may be completed by plants in several alternative sets of environmental factors. At least in some plants, the alternative inductive factors are perceived by different organs, indicating that these factors affect most probably entirely different processes. Thus the shoot meristem appears to be controlled by a complex and flexible array of promoters and inhibitors arising from all plant parts. At meristem evocation, there are a number of events which are fundamentally the same in many plants, but so far no single initial critical event has been found.
The transition from the vegetative to reproductive buds is usually activated  by an environmental signal, typically photoperiod or temperature. This signal synchronizes flowering to environmental events that plants use to coordinate actions with the season.
In some plants, an environmental signal is not necessary to activate the transition to the determined state. These plants move directly in the reproductive phase after becoming competent.
Ultimately, one or more of these factors likely induce changes in hormones such as GA (Gibberellic acid); for example GA application stimulates the adult phase in conifers but in ivy promotes juvenility





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