What a wonderful, sweet question! It ranks right up there with the question for mom's everywhere: "Why is the sky blue?" The answer is actually the result of a VERY scientific process and not just that, "God made them that way." Although, that is certainly a simpler answer.
The green color of leaves is produced through the process of photosynthesis. The leaves appear green due to the color of chlorophyll in the photosynthesis process. Many people mistakenly believe the leaves "natural" color is green. However, a tree reveals its truly unique colors in the fall when the chlorophyll retreats in the leaves, leaving the "natural" color to be seen for a short time before falling from the tree.
This process is unique to deciduous trees as conifers continue their photosynthesis cycle throughout the year. Chloroplasts hold the proteins that are converted in photosynthesis. These chloroplasts are inside the organelles of the plant. The chloroplasts are tinted green, hence the coloring of the green leaf in the process.
Photosynthesis is a light dependent process which explains the retreat of the chloroplasts as the days become shorter after the autumnal equinox. The length of lighted time signals the chloroplasts to begin their retreat and "hibernation" for the shortened days of the winter season.
After the spring equinox, the lengthening of days signals the deciduous hardwoods to sprout the leaves which will immediately begin the process of photosynthesis and the output of green-tinted chloroplasts. So, as you can see, the trees actually "know" what to do because of the sun's placement in the sky!
Such a very scientific answer to what seems such a simple question!
Leaves are green due to chlorophyll (a green pigment) in the chloroplasts (an organelle found in plant cells). Chlorophyll absorbs red and blue wavelengths and reflects green wavelengths. Chlorophyll is very important in photosynthesis!
The chlorophyll which helps to phtosynthesize makes the leaves green
Leaves have chlorophyll which plants use to photosynthesize. The chlorophyll helps give the plant nutrition. The chlorophyll absorbs red and blue waves which makes the leaf appear to be green to our eyes.