By ROBERT DRYJA
Los Alamos

Autumn is now entering its peak for the seasonal change of leaves. Trees of all kinds had green leaves during the summer. The leaves were making nourishment for the rest of the tree by absorbing carbon dioxide from the air and making more complex carbon compounds.

Oxygen was released into the air as a by product. This process, called photosynthesis, is now stopping with winter coming. Green leaves no longer make nourishment but instead dying away until next spring.

Maple trees can have a particularly colorful change. The hundreds of green leaves change color altogether. A maple tree seen at a distance can be a mass of green one week and then a mass of red a couple of weeks later. A closer look shows that an individual leaf has red veins that grow from a starting stem called a petiole.

They then spread throughout the rest of the leaf that may still be yellow. During the summer these veins were transporting water and particular kinds of nourishment to the leaf so it could grow and have photosynthesis.

Picture 1: A Red Maple tree can become a mass of dramatic red and yellow color when seen at a distance. Courtesy photo

Maple leaves have a similar design for a particular species. Three major veins grow from a petiole on one side of a Red Maple leaf. These three veins then extend into three major sections of the leaf called lobes. Smaller veins then extend from a major vein, going into smaller sections of a lobe.

Picture 2: Redness first appears in the veins of a leaf. Courtesy photo

Although Maple trees may be changing for winter, individual trees vary in when they start to change. For example, a Silver maple tree species may still have green leaves while a Red Maple tree species is changing color.

They do not follow the exact same time schedule and may vary by a couple of weeks from one species to another.

Picture 3: The design is very similar for the leaves of a particular maple tree species. Petioles from several leaves come together at a small stem that then connects to a tree branch. Photo by Robert Dryja 

Picture 4: A Silver Maple still has green leaves while a Red Maple has changed color. A Silver Maple leaf has five lobes while a Red Maple leaf has three. Photo by Robert Dryja