This may seem like an easy question at first. We see trees everywhere and we know what they are when we see them, but what is it that really makes a tree, a tree? The first part of the description is fairly easy. A tree has a woody stem and is a perennial, meaning that it lives for many years. However, there are bushes and other plants that fit this description and aren't really trees. There isn't a scientific description of a tree so most people and books use a rule of thumb. If a plant has a woody stem, is perennial, and grows to more than 13 feet tall. Of course, there will always be tree-like bushes and bush-like trees, but, for the most part we know a tree when we see one. Types of Trees Conifers and Evergreens Coniferous trees have narrow hard leaves called scales or needles. Most of them are evergreen, meaning that they stay green during the winter and don't have leaves that change colors and drop during autumn season. Conifers get their name from having cones that house their seeds. Some examples of conifer trees include cypresses, pines, cedars, firs, and redwoods. Conifer trees are famous for having the tallest and largest forms of life. These trees are the giant sequoias or redwood trees. They can be found at Redwood National Park in California. The giant redwood trees grow to 115m (379 feet) tall. That's a tree taller than a football field is long! Deciduous and Broadleaf Trees Another type of tree is the broadleaf. Most broadleaf trees are deciduous, meaning that they shed their leaves each fall. The name broadleaf comes from their wide leaves, unlike the thin needles of the conifers. These trees also produce flowers. Sometimes the flowers are in the form of fruit or nuts, which we can often eat. Some examples of broadleaf trees are oaks, beeches, maples, elms, and birches. How do trees grow? Trees grow in a few places. First they grow taller by growth from new cells at the tips of their branches. They also grow roots to collect water and nutrients from the soil. The roots grow at the tips like the branches. Trees also grow wider in their trunks and branches. This growth takes place out the outer later called the cambium. Since growth of the cambium stops during the winter or cold months, tree trunks develop rings. Each ring represents a year of growth. We can see how old trees are by counting their rings.  Diagram of rings in a young conifer from Fritts, 1976
Other tree features
Trees have provided humans with building materials for homes, furniture, and more over all of human history. Trees have also been a great source of fuel as fires for keeping warm and cooking food. We also gather a lot of our food from trees such as fruit and nuts. However, trees are also important to our environment. Trees are a primary source of oxygen. They breathe in and reduce carbon dioxide and in turn provide oxygen. We couldn't live without trees! On top of that trees provide us with shade and beauty, so be sure to hug a tree today! More biology subjects: The Cell Bacteria Photosynthesis Trees Animals Scientific Classification Nutrition Vitamins and Minerals Back to Kids Science Page Back to Kids Study Page Back to Ducksters Kids Home Page |
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