Kids Research Express

Calabash Tree (Crescentia cujete) of the trumpet-creeper family (Bignoniaceae), 6 to 12 metres (20 to 40 feet) tall, that grows in Central and South America, the West Indies, and extreme southern Florida. It is often grown as an ornamental. It produces large spherical fruits, up to 50 cm (20 inches) in diameter, the hard shells of which are useful as bowls, cups, and other water containers when hollowed out. The fruit's shell encloses a whitish pulp and thin, dark brown seeds. The tree bears funnel-shaped, light green and purple-streaked flowers and evergreen leaves. Fruits of the unrelated bottle gourd (Lagenaria siceraria) are also known as calabashes. In some countries the rind and juice are used for medicinal purposes.

The major parts of a tree The major parts of a tree are its roots, trunk, leaves, flowers, and seeds. These components play vital roles in a tree’s growth, development, and reproduction. A. Roots Trees are held in place by anchoring organs called roots . In addition to anchoring the tree, roots also absorb water and minerals through tiny structures called root hairs. From the roots the water and mineral nutrients are carried upward through the wood cells to the leaves. Although the internal structure of most kinds of roots is similar, there are often external differences. Pines, for example, have a strongly developed taproot, or main root, in addition to branching side roots. In maples, on the other hand, there is little or no central taproot, and the other roots are produced in great numbers near the surface of the soil. Roots grow constantly, and at the growing tip of each root is a region called the meristem, which is composed of special rapidly dividing cells. Just behind the meris

Types of Trees There are two general types of trees, angiosperms and gymnosperms . Angiosperms are flowering plants in which the ovule, or seed, is encased in a protective ovary. With about 235,000 species, the angiosperm division is the largest and most diverse plant group. It is divided into dicots , plants with two cotyledons (seed leaf structures), that include the familiar broadleaf trees such as maple and oak ; and the monocots , plants with one cotyledon that include the palms and lily trees. Unlike angiosperms, gymnosperms (Greek for “naked seed”) do not bear flowers. Their seeds lie exposed in structures such as cones or fleshy cups called arils. The group includes about 500 tree species—including three major types, needle-leaf trees (or conifers ), ginkgos , and cycads . A. Angiosperms As angiosperms, all dicots produce flowers, and their seeds are always enclosed in a protective covering. In temperate regions, most of these broadleaf trees are deciduous, meaning that they

Importance of trees Perhaps the most important ecological function of trees is protecting the land against erosion , the wearing away of topsoil due to wind and water. The trunks and branches of trees provide protection from the wind, and tree roots help solidify soil in times of heavy rain. In addition, trees and forests store water reserves that act as buffers for the ecosystem during periods of drought. In many areas the removal of forests has resulted in costly floods and subsequent droughts. Trees and forests also provide habitat, protection, and food for many plant and animal species. In addition, they play an important role in global climate and atmosphere regulation—the leaves of trees absorb carbon dioxide in the air and produce oxygen that is necessary for life. Trees have many economic uses. Lumber from trees is the most widely used material in the building of homes and other structures. Many trees yield edible fruits and nuts such as oranges, grapefruits, apples, avocados,

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