Every spring, the process of flowering plant growth unfolds before your eyes. New shoots push free of seeds and the earth, sometimes growing several inches of new stem and leaves in a single day. When the time is right, buds spring open, presenting the bright flowers that, if pollinated, will produce the next year's seeds.
All flowering plants begin as seeds, small structures that contain a plant embryo and a nutritive substance called endosperm, all wrapped in a protective seed coat. Germination begins when conditions are ideal. Water absorption and increased enzyme activity spur rapid growth in the embryo, which pops free of the seed coat. A tiny root anchors the plant in the ground, and its first infant leaves reach for the surface.
All plants undergo vegetative growth, the growth of structures not concerned with reproduction. The growth of stems, roots and leaves are all vegetative processes. At the cellular level, growth occurs through a process called mitosis, in which cells duplicate their contents and then split, forming two cells from one. Plant growth occurs in regions called meristems, where rapid mitosis allows stems to elongate, roots to extend and leaves to develop.
Special meristems produce flower buds, initiating a different type of growth in the flowering plant. Flowers are reproductive structures, producing sex cells and undergoing sexual reproduction to produce a new generation of seeds. Rings or whorls of tissue in the meristem differentiate into the parts of the flower: sepals, petals, stamens and the pistil. Within these latter two structures--the male and female parts of the flower, respectively--a special kind of cell division called meiosis produces sex cells that, when fused through pollination, generate seeds.
Plants develop flowers only at certain times of the year. There are multiple ways that plants know when to begin growing flowers. First, normal meristem must transform into floral meristem, which forms flower buds. Some plants know to do this by temperature changes or when they receive a certain amount of light, indicating the time of the year for growth. Plant maturity is also a factor, which is why young trees often will not produce flowers for several years. Their energy is being poured into vegetative growth rather than flower development.
Understanding how your plants grow helps you to make decisions in the garden. Pruning a plant after flower buds have been set, for example, will often prevent flowering the following year. Furthermore, all growth requires the plant's energy resources. When plants don't receive enough inputs of light or water, or when other conditions affect their ability to produce energy, growth is directed where it is most needed, which is often away from flowers.