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Scientists use a tool called a key, sometimes a "dichotomous key," to categorize and identify different varieties of things. There are keys for identifying trees, keys for identifying insects, keys for identifying birds. Whether online or in book form, the keys are essentially a system of "Twenty Questions." For example, if we wanted to identify a tree from one of these keys, perhaps the first question would be "Is the tree deciduous or coniferous (broad leaves or needles)?" If the tree fit the first category, the key might instruct us to turn to a specific page to answer more questions. The next question we might answer could say, "Are there many leaves on a stem, or only one?" Our answer to this question would lead us to another specific question. In this way, the key narrows down the possibilities based on the characteristics of the tree we are looking at. After we have identified enough key points of the tree, the key will tell us what the tree is. It's amazing how many different kinds of trees there are! All of them are important to our ecosystem and all of them make our world green and beautiful, but each species of tree has something special and different that sets it off from the others and makes it individually important.
