ABSTRACT
Evocation is classically viewed as the result of the generation of a specific floral hormone in conditions that promote flowering. This hormone when reaching the receptor meristem is believed to produce a single, highly specific event which then sets in motion the complex sequence of other evocational changes. The specificity of floral evocation has been questioned by L. T. Evans and other investigators on the basis that most of the events so far detected during evocation are not specific to flowering. The weight of the evidence indicates that an inhibition of vegetative growth is incidental to some flowering systems, but is by no means a universal and essential component of evocation. Much work was aimed at determining the time of irreversible commitment of meristems to flower formation. In nature, "vegetative" structures may arise spontaneously within inflorescences or flowers of many species; the malformations were termed "teratisms" by morphologists.
