Tree

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Tree, woody plant with a distinct main stem, or trunk. At maturity, trees are usually the tallest of plants, and their height and single main stem differentiate them from shrubs, which are shorter and have many stems. Trees are perennials, plants that live for at least three years. Some species of tree only grow to 4 m (13 ft) in height, but the tallest species may reach heights of more than 112 m (more than 367 ft). The General Sherman Tree, a giant sequoia in California’s Sequoia National Park, has a height of 84 m (275 ft) and a diameter of 11 m (37 ft). The largest trees, however, are not necessarily the oldest. For example, the bristlecone pine grows to a height of only about 9 m (about 30 ft), but one specimen has been dated as at least 4,600 years old.

Trees grow throughout the world, from the extreme cold regions near the Arctic and the Antarctic to the hot tropical regions around the equator. They grow in both good and poor soil, in deserts and swamps, along shores, and at mountain elevations of several thousand feet. Although trees may grow singly, under natural conditions they more often grow in stands, which consist either of one species or of a mixture of species. A forest is a plant community made up of the trees, shrubs, and herbs that cover an area. Throughout much of North America, forests include only a few species of trees. In tropical forests, however, large numbers of different species can be found in very small areas. A survey of a 1-hectare (2.5-acre) plot in the Brazilian rain forest determined that it contained 476 tree species.

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