Pine Needle

The pine needle unlike the others has one epidermal cell because it is round. Just like the others under that is the palisade mesophyll cell and then the air inside with the spongy mesophyll cells bouncing around inside. The vascular bundle in the pine needle is through the heart of the needle and have chloroplasts connected to it. The stomas on the pine needle are all around the outside of the needle. On some versions of tree needles you can see the stomas on the outside quite clearly with the human eye.