Primary growth is responsible for growth in length of roots and shoots A. Most plants grow as long as they live 1. This is called indeterminate growth 2. Annuals complete their entire life cycle in a single year or growing season 2. Biennials complete their life cycle in two years a. Flowering usually occurs in the second year 3.
Perennials usually live for several years a.
Some perennial plants are amongst the oldest organisms alive i. Giant sequoias are known that are about 3000 years old ii. Bristlecone pines can outlive sequoias by several thousands of years iii. Some aspen clones in the Rocky Mountains are thought to be as many as 10,000 years old C. Growth occurs at meristems 1. These are called apical meristems i. They consist of rapid-growing, relatively undifferentiated cells D. Lengthwise growth produced by apical meristems is called primary growth 1.