Generation of photo-realistic images of virtual nature scenes is a challenging topic in computer graphics. As a very important part of natural scenery, realist ic rendering of trees has attracted much attention. Trees have various types wit h different shapes and due to their complex structures, realistic modelings, ren dering and storage of trees are always a tedious task. To tackle the problem, di fferent rendering strategies ae employed according to different types of trees a nd different scenes. For broadleaf, the z-buffer shadow generation method is us ed based on primary functions of OpenGL, for conifer, a ray tracing algorithm in cluding texel-rendering technique is used, and for trees in the far distance, v olumetric texture mapping is employed in terms of ray tracing and volume renderi ng technique. The images produced show that the feasibility and validity of the proposed rendering techniques.