Why leaf fall

At the point where the stem of the leaf is attached to the tree, a special layer of cells develops and gradually severs the tissues that support the leaf. At the same time, the tree seals the cut, so that when the leaf is finally blown off by the wind or falls from its own weight, it leaves behind a leaf scar.

Most of the broad-leaved trees in the North shed their leaves in the fall. However, the dead brown leaves of the oaks and a few other species may stay on the tree until growth starts again in the spring. In the South, where the winters are mild, some of the broad-leaved trees are evergreen; that is, the leaves stay on the trees during winter and keep their green color. Most of the conifers - pines, spruces, firs, hemlocks, cedars, etc.

The needle- or scale-like leaves remain green or greenish the year round, and individual leaves may stay on for two to four or more years. Temperature, light, and water supply have an influence on the degree and the duration of fall color. Low temperatures above freezing will favor anthocyanin formation producing bright reds in maples. However, early frost will weaken the brilliant red color.

The best time to enjoy the autumn color would be on a clear, dry, and cool not freezing day. Apply Give Partner. To do this, the leaf needs water. This water comes from the soil, and is sucked up through pipes in the trunk and branches all the way to the leaves — this can be a very long way for tall trees!

This way, they can be recycled. When the leaf is empty, the tree stops holding onto it and it falls to the ground, or blows away in a gust of wind. Read more: Curious Kids: how can a tiny seed actually grow into a huge tree? Some trees lose their leaves every year. These trees are called deciduous trees, and they lose their leaves in response to the seasons. Deciduous trees mostly come from places where winter gets cold and snowy.

When it is very cold, the water in the tree can freeze — the leaves stop working and can even be damaged by the ice crystals. These trees know to prepare for this, and start taking nutrients out of the leaves when the days get shorter in autumn — this is when we can see them changing colour. Family Programs. Homeschool Programs. Girl Scout Events. Member Events. Museum at Home. Holiday Events. Join Our Team. Traveling Exhibits. Community Programs. Power of Children Awards.

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