Junipers have a few distinguishing characteristics. They can be big trees, medium sized shrubs or found trailing along the ground. They can grow at pretty high elevation and extreme climates. Often the tree has needle-like or scale-like leaves. Needle-like leaves are most commonly found on younger plants, but sometimes old branches, and some species retain the needle-like leaves. The scale-like leaves are often found on juvenile leaves or older. I’m sure there is an adaptive advantage to having these different leaf types.