What Happens to Plants in Winter?

Lucy takes Amir to an outdoor area with many different trees. The leaves on most of the trees are green but some are yellow. Amir asks, "Why do leaves change color?" "Some leaves change color because they stop making food," Lucy says. "This happens in the fall. The leaves turn red, orange, yellow and brown. The leaves fall off trees to save energy."

"Why do leaves fall off trees in the fall?" asks Amir. "In winter, the weather is cold," says Lucy. "Leaves will freeze because they are flat and thin. Water cannot move to the leaves. Sugar cannot move to the rest of the tree. That means the leaves cannot make food. So, the trees stop making food before winter."

"Some plants and trees die in the winter," says Lucy. "They drop seeds to make new plants. But many plants and trees will rest during winter. They use energy stored from the food they make in the summer to stay alive. Trees and plants that do not grow in the winter save energy."

"When do plants and trees start growing again?" asks Amir. "In the spring, the weather gets warmer. Trees begin to use the stored energy to grow new leaves," says Lucy. "The new leaves are green. They have chlorophyll in them. Now, the leaves can make more food."

Amir points to the pine trees. "How do pine trees stay green in the winter?" he asks. "Pine trees are a kind of evergreen tree," says Lucy. "Evergreen trees stay green all year long. They do not lose their leaves in the winter. Evergreen trees can make food and put oxygen into the air even during winter."

"Pine trees have long, thin and pointy leaves called needles," says Lucy. "These needles are leaves that make food for the plant. The needles use light energy to change water and carbon dioxide into sugar and oxygen. The sugar is used for energy to help the plant grow. Photosynthesis is the way plants make food."

"Why are the needles long and thin?" asks Amir. "Evergreen trees grow in cold, dry areas. The needles are long and thin, so they do not freeze. They have a thick skin covered in wax to help keep water inside. Pine trees do not grow flowers or fruit like other plants and trees. Pine trees grow pine cones," says Lucy. "The pine cones have seeds to make new pine trees."

"Some plants can store their energy from the food they make to stay alive during winter," says Amir. "Other plants with special leaves do not rest. They can make food even in winter. This keeps their leaves green." "That is correct," says Lucy. "Now let me show you a plant that doesn’t have leaves, but can still make food."