ABSTRACT
This chapter deals with the general systems of measurement that can be used with all species and the specific ones that are used for particular developmental aspects or for certain economically valuable plants. It provides the qualitative features of flower development. The simplest measurement of flower development is the determination of the proportion of plants reaching a predetermined stage, e.g., anthesis. The general systems of measurement usually provide estimations of the rate of development of the reproductive structures and their ability to achieve normal development to anthesis. In stage systems concerned with the development of a single flower, a whorl of floral parts usually represents a single developmental stage. In some species flower development is fortunately under relatively strict control of the environment — photoperiod, light flux, or temperature. In studies devoted to sex expression, the ratio of male to female flowers is frequently used. This ratio serves as a measure of sex tendency.
