Science College, General Science Dept
Our first Botany course involved the history of Botany and told a bit about the broad structure of the science. In Part II, we will study plants, their structure, types, and the special relationship between plants and felines. PLANT STRUCTURE Plants can be either herbaceous or woody. Most herbaceous plants usually have stems that are soft, green, and contain little woody tissue. These plants are ones that usually die to the ground each year. Most annual and perennial flowers fall into this category along with vegetables and houseplants.
Woody plants are perennials (plants that live more than two years) that create stiff structures above ground that they use throughout their lives. They may be divided into three groups: trees, shrubs and vines. Trees and shrubs are self-supporting. Vines climb on other plants or on inanimate structures like a fence or a wall. They all develop an inner "backbone" - wood - for support and a tough outer "skin" - bark - for protection. This strategy allows them to get closer to the sun. All plants are in competition with each other for sunlight, which is the energy source that they capture to power photosynthesis within their cells. Any plant that can grow taller than its neighbors will be more successful in this competition. A woody stem allows this. A plant's LIFE CYCLE describes how long a plant lives or how long it takes to grow, flower, and set seed. Plants can be either an annual, perennial, or biennial.
ANNUAL: A plant that completes its life cycle in one growing season. It will grow, flower, set seed, and die.
Examples: marigolds, tomatoes, and petunias.
PERENNIAL: A plant that lives for 3 or more years. It can grow, flower, and set seed for many years. Underground parts may regrow new stems as in the case of herbaceous plants, or the stems may live for many years like woody plants (trees).
Examples: daisies, chrysanthemums, and roses.
BIENNIAL: A plant that needs two growing seasons to complete its life cycle. It grows vegetatively (produces leaves) one season, goes dormant or rests over the winter, and then grows flowers, sets seed, and dies the second season.Examples: parsley, carrots, and foxglove.
[Next | Exam]