Inflorescence is the arrangement of flowers on a stem that is composed of a main branch or a complicated arrangement of branches. It is the modified part of the shoot of seed plants where flowers are formed on the axis of a plant. The modifications can involve the length and the nature of the internodes and the phyllotaxis, as well as variations in the proportions, compressions, swellings, adnations, connations, and reduction of main and secondary axes. The stem holding the whole inflorescence is called a peduncle, and the major axis above the peduncle bearing the flowers or secondary branches is called the rachis. The stalk of each flower in the inflorescence is called a pedicel.
There are two types of inflorescence: racemose and cymose. In racemose inflorescence, the flowers branch laterally on the floral axis, and the floral axis keeps on growing, and the flowers develop in an acropetal pattern. In cymose inflorescence, the flowers are arranged in a centrifugal manner, and the floral axis terminates in a flower. Inflorescence can also be categorized based on the timing of its flowering as determinate and indeterminate. In determinate (cymose) inflorescences, the youngest flowers are at the bottom of an elongated axis or on the outside of a truncated axis. At the time of flowering, the apical meristem produces a flower bud, thus arresting the growth of the peduncle. In indeterminate inflorescences, the youngest flowers are at the top of the axis, and the axis continues to grow after flowering.
