life cycle
Plant Life Spans The length of time from the beginning of development to the death of a plant is called its life span. The life cycle, on the other hand, is the sequence of stages a plant goes through from seed germination to seed production of the mature plant. Some plants, such as annuals, only need a few weeks to grow, produce seeds and die. Other plants, such as the bristlecone pine, live for thousands of years. Some bristlecone pines have a documented age of 4,500 years Figure 32.29. Even as some parts of a plant, such as regions containing meristematic tissuethe area of active plant growth consisting of undifferentiated cells capable of cell divisioncontinue to grow, some parts undergo programmed cell death apoptosis . The cork found on stems, and the water-conducting tissue of the xylem, for example, are composed of dead cells.