When plants are mentioned, most people visualize one of the large dominant plants of their region—perhaps a cactus for desert dwellers, or a vista of waving grasses in the prairie, or tall sycamores along a river in the Midwest. All of these plants are angiosperms or flowering plants. Except for the trees of the coniferous forests, most of the large, visible plants around us in the temperate zone and the tropics are angiosperms. In past geologic eras they did not form the dominant vegetation During earlier eras, gymnosperms, ferns, or fern allies were the principal players on Earth, and before a terrestrial flora appeared, bacteria, algae, and protista colonized the primeval waters.
There are close to 300,000 described species of angiosperms in the world. They are the plants we rely on for our food and shelter. They are feed for livestock and provide us with aesthetically pleasing landscapes and gardens. They make all life possible by capturing the energy of the sun and transforming it into a form usable by animals.
Angiosperms are studied in thousands of laboratories and fields and probably more is known about their characteristics than those of any other plant group.
In most introductory plant biology texts, the term “plant,” unless designated otherwise, generally refers to an angiosperm and “typical” plants are flowering plants. Note, however, that while most plants share many of the same types of tissues, cells, and functions, there is no typical plant with all of the described characteristics; in the real world there probably are exceptions to almost all of the textbook generalities made about “typical” plants.
Flowering plants have stems, leaves, and roots and reproduce by seeds located in fruits produced in flowers. As most of these structures are distinctive, neither a microscope nor the help of a botanist is needed usually to identify the various parts. Study of the details of plant structure is an important part of plant biology because plant function is integrated inextricably with form and structure. To know one helps in understanding the other. A knowledge of structure leads to a greater appreciation of how well-designed plants are for carrying out their functions.
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