In Photoshop CC, you can generate realistic looking trees by using the tree generator found in the Filter menu under Render > Tree…
In the Tree window, you can choose different attributes for your tree, such as the type of tree, light direction, camera tilt, and the amount of leaves it has. After you set your options, press OK and Photoshop will generate a tree that you can use in your composition. The branches and leaves are generated randomly, so you will never have two identical trees.
The trees below were created using this method.
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