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EXAMINING STEMS AND LEAVES One of the jobs that a leaf has to do is to protect the stem from the hot sun. Did you know that stems can actually get sunburned, just like we can? The leaves offer some shade to the stems, and they grow out from the stem in the best way to protect the stem of the particular plant on which they grow. There is a pattern in the ways that leaves grow from stems. Plants that are the same will have the same pattern, because they reproduce their own kind. Each kind of plant has its own pattern. Yet, they all have some of the same characteristics, and that pattern is the one we will study now. We'll take a little walk around the schoolyard, and examine the different plants. We can do the same thing later, at home, by examining plants in our own yards and the yards of our neighbors. The leaves of grasses (called "blades") grow right out of the stem. Most leaves of other plants are attached to the stem by a little stalk (tiny stem) called a "petiole" (pronounced "pet-tee-ol"). At the base of the petiole on some plants, there are two tiny leaf-like things that stick out, called "stipules" (pronounced "stip-yules"). Most plants don't have stipules. The swollen places on stems are called "nodes," and this is where leaves grow. On some plants, there will be only one leaf at each node. Then, there will be a pattern in which the nodes (or leaves) will take turns being on different sides of the stem. Some will grow toward the sun, and some will grow toward the ground. If you look at each leaf or node, and count them, you will see that #1 is toward the sun, #2 is to the side. #3 is to the ground, and #4 is growing to the other side. The next #1 will be in the same position as the first # 1. Some will grow toward the sun and others will grow toward the ground. This is called a "spiral pattern." How many plants can you find with their leaves growing in this same kind of spiral pattern? On other plants, there will be two leaves growing from each node. They will have leaves growing out on only two sides of the stem, and they will be on opposite sides. The leaves will not grow out from the top side and bottom side of the stem, but will turn to face the sun, and unless you look closely at the stem, you will think all the leaves grew out from the top of the stem. See how many different plants you can find with this opposite pattern, and put them on your list. I just looked at the new growth on my hackberry tree. It has nodes on all sides of the stem, in a spiral pattern. From each node, there grew one petiole with a leaf, and another little stalk with three tiny stalks growing out from its terminal bud. The three tiny stalks each have one very tiny flower on the ends. Those flowers will grow into black- colored berries. The birds will enjoy most of those berries next winter, and some of the berries will start new trees, because they are the tree's seeds. Some stems have more than two leaves growing out from their nodes. These leaves are whorled, which means that the edge of one leaf is on top of, and at the center of the leaf that came before it. Kind of the way playing cards are "whorled" in your hand when you hold several at one time. There are a few plants which have more than one pattern of leaf growth. See if you can find one. You could be a leaf- pattern detective! That would be fun!  Any problems with this page? Send URL to
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