Animals aren't the only ones working hard to make it through the cold months.
Plants make and store food to help them live and grow throughout the summer months when there are many hours of sunlight and a good supply of water. When winter time comes, the amount of sun and water available is greatly reduced. People cope with this change in the weather by wearing coats and warmer clothing. Plants, in turn, have their own ways of preparing for the cold season.
Plants that complete their life cycle in one growing season are called annuals. In the fall, annuals die and will not grow back, but their seeds get left behind, waiting to sprout the following spring.
Perennial is the name for a plant that lives for more than two years. When winter comes, the roots and woody parts of the perennials will survive the cold. Other parts of these plants located above ground, such as the leaves, die off each year. In the winter, perennials rest and live off stored food until spring.
Can you identify an example of an annual plant and a perennial plant near your home?
Trees are an example of a perennial plant. Deciduous trees are those that prepare for winter by losing all their leaves. Through the summer, leaves make glucose to use for energy.
Excess glucose is turned into starch and stored until needed. The base of each leaf has a layer of cells called the separation layer. In this layer, there are small tubes that bring water into the leaf and food back to the tree.
In the fall when there is less sunlight, plants stop producing energy and the cells in the separation layer swell causing the flow between the leaf and tree to stop. This is when the leaves begin to change colors due to the lack of water entering the leaf. Then the cells in the separation layer begin to disintegrate until the leaf becomes detached from the tree by an autumn wind or falls off on its own.
How many trees near you have lost all of their leaves already? Are there any that still have all of their leaves? Watch as the months progress to see how the trees change.
Not all perennial trees lose their leaves in the winter. Conifers, often called evergreens, have leaves that are resistant to cold and moisture loss. Some, like pine and fir trees, have long thin needles. Others, like holly, have broad leaves. Evergreen leaves and needles can continue to produce energy during the winter as long as they get enough water.
What type of evergreen plants are near your home?