WHAT IS A TREE Trees cover nearly 30 percent of Earth’s land surface They Trees cover nearly 30 percent of Earth’s land surface They can thrive in many different environments tundra deserts rain forests and mountains Sometimes people take trees from their native areas and grow them elsewhere Trees can be used to make a wide variety of everyday products such as paper clothing candles shampoo tires toothpaste and much more WHAT DO TREES DO Trees do a lot of work to keep Earth healthy People sometimes call them the lungs of the Earth That’s because they can do many things including Filter polluted air Produce oxygen Provide food and shelter for animals insects and people all over the world Store carbon in their leaves and trunks Because of a tree’s ability to store carbon there’s growing evidence that planting more trees and stopping the destruction of forests can help counter the negative effects of climate change CATEGORIES OF TREES Scientists often define a tree as a living organism that has a root system woody stem and branches that form a crown True trees typically grow to be at least 12 feet 3 6 m tall They are also perennial plants which means they continue to grow year after year Trees belong to two main categories of plants Trees belong to two main categories of plants gymnosperms and angiosperms gymnosperms and angiosperms
A gymnosperm is a plant that doesn’t flower and reproduces by creating exposed seeds these are called seed cones Conifers cycads ginkgophytes and gnetophytes are all gymnosperms Many more trees belong to the angiosperm category of plants An angiosperm is a flowering plant that produces fruit containing seeds Apple trees maples and palms are all angiosperms There is a third category of tree-like plants called pteridophytes But these aren’t true trees Most of these plants are shrubs or ferns TREE IDENTIFICATION When identifying a tree it helps to pay attention to the following characteristics Height Most tree species have an average range Overall shape Trees can grow in many different shapes from tall and narrow to large canopies with multiple trunks Bark The bark is the protective layer on the tree’s trunk and branches It can be a variety of textures and colors Leaves One of the easiest ways to identify a tree is to examine its leaves Leaf shape color texture and arrangement can give people clues about the tree’s identity Flowers fruit and seeds If a person examines a tree during the spring or fall he or she can also use the tree’s flowers fruit or seeds to help identify it
HOW TO USE THIS BOOK Tab shows the tree category The tree's scientific name appears here ANGIOSPERMS ALOE YUCCA YUCCA ALOIFOLIA The aloe yucca is also known as the Spanish bayonet tree it has long sword like leaves that can be leaves grow along the tree's entire trunk 1 and often fall off once they die The fthe tree is the very top where a crown of in a sunburst shape The aloe yucca's leathery begin as large white flowers The tree's common name appears here FUN FACT Angiosperms are the largest and most diverse group in the plant kingdom This group includes species of flowering plants Fun Facts give interesting information related to the tree HOW TO SPOT Height 5 to 20 feet 1.5 to 6 m Leaves Pointed leaves 2 feet 0.6 m long Fruit Fleshy green to black pods 3 to 4 inches 7.6 to 10 cm long Range Southern United States Habitat Coastal areas YUCCA PLANTS All yuccas are evergreen plants that have thick blade like leaves and that usually grow in warm dry climates There of yucca plants worldwide but most Sidebars provide additional information about the topic
JOSHUA TREE YUCCA BREVIFOLIA The Joshua tree is the tallest of all yucca plants This slow growing tree has long thin leaves that grow spiky clusters at the ends of its branches The branches of the tree are usually covered with a shaggy layer of dead leaves In the spring the produces pale green flowers that transform into egg shaped seeds This paragraph provides information about the tree HOW TO SPOT Height 20 to 40 feet 6 to 12 m Leaves Spike like 12 inches 30 cm long Fruit Egg shaped 2 to 4 inches 5 to 10 cm long Range Southern California Habitat Desert How to Spot features give information about the tree's height leaves fruit seeds range and habitat Images show the tree FUN FACT The Joshua tree is a very rare tree It grows only in one small region of the world the Mojave Desert
