We often think of the leaves of broad-leaved trees that, like oaks, have fairly broad leaves and rustle in autumn. But like a pine tree, a conifer with needle-like leaves, or an evergreen tree like the camellia, which is green all year round, there are also deciduous trees. Unlike broad-leaved trees, which are colorful in autumn, conifers and evergreen trees only lose a little bit of leaves throughout the year. In the fall and winter, when the weather is cooler and less sunlight, trees choose whether to carry their leaves or let them fall. When the weather gets cold, the plants have a lot of water, so it is easy to freeze.
And winters are not only cold, but also very dry. 02 phone database Photo Credit: Daejeon Publishing Moisture is easily lost through large areas of leaves. Ultimately, with less sunlight, trees make a trade-off between maintaining the energy of the photosynthetic leaves, or the energy produced through sunlight. Deciduous broadleaf and evergreen trees make different choices on this issue. Pick up the fallen leaves in autumn, and you can see that the leaves have petioles. From a leaf, the petiole is quite slender relative to the huge leaf body area. Even though it looks fragile, it is designed to be very strong in order to grow firmly on the tree for a long time in spring and summer.
Plant cells are held together tightly with a glue called pectin. As leaves fall, this adhesive between the end of the petiole and the branch decreases and the cells change. The position where the leaves are separated is called the "detachment zone", which is further divided into a protective layer and a separation layer. When the leaves fall, the cells of the separation layer gradually become fragile and separate. But after the leaf falls, its position is exposed like an injury. Therefore, bacteria or fungi from the outside can easily invade the inside of the tree. To prevent this, a protective layer is built under the separation layer to make the cells strong. After the leaves fall, that part protects the tree as hard as the bark.