When we are enjoying flowers, we will find that some plants only have one flower on a branch, such as peonies, roses, and tulips. These flowers, which are only found at the top of the stem or in the leaf axils, are called solitary flowers. However, most plants have many flowers on a branch, such as snapdragons, orchids, and foxglove. Many flowers are arranged according to a certain pattern on the inflorescence axis, and this type of flower arrangement is called an inflorescence.
The development of inflorescences is the first step in flower development, marking the transition of a plant's individual growth from vegetative growth to reproductive growth. When entering the reproductive growth phase, the meristem at the top of the stem of a plant acquires the properties of an inflorescence or flower meristem, thereby continuously differentiating new inflorescences and flowers. If the inflorescence meristem of a plant quickly transforms into a flower meristem, only one flower will form at the top of the branch. However, if the inflorescence meristem of a plant can maintain its inflorescence-forming ability for a certain period of time and continuously differentiate new flower meristems on the inflorescence, multiple flowers will form at the top of the branch. The inflorescences formed by the meristem at the top of a plant's stem can be divided into limited inflorescences and unlimited inflorescences. According to the number of branches, inflorescences can also be divided into simple inflorescences and complex inflorescences. The interaction of genes controlling the properties of inflorescence meristem and flower meristem determines the structure of the inflorescence.
During the development of unlimited inflorescences, the main functions of the CENTRORADIALIS (CEN) and TERMINAL FLOWER 1 (TFL1) genes are to maintain the development of inflorescence meristem and play a key role in inhibiting the transformation of inflorescence meristem properties into flower meristem. After mutations in these two genes, the inflorescence meristem of a plant will transform into a terminal flower during reproductive growth, and the inflorescence will be transformed from an unlimited inflorescence to a limited inflorescence.