This is a magnified cross section of a pine needle. It is a beautiful and intricate structure, with many different parts that work together to keep the pine tree healthy. The outer layer of the pine needle is called the epidermis. It is a protective layer that helps to keep the needle from drying out. Beneath the epidermis is the mesophyll. This is the photosynthetic … [Read more...] about Magnified Cross Section of a Pine Needle