Plants come with complicated structures and lots of details. They are also very common in our daily lives. In computer graphics, to render a realistic outdoor scene, plants are often needed to be constructed. In many cases, we don't need to reconstruct a specific tree, but more likely expect the tree to be realistic looking. There are a large number of literatures looking at different approaches of generating trees or other plants in the computer. Practically, you can use e.g. L-system (http://en.wikipedia.org/wiki/L-system) with carefully chosen rules to simulate trees of different varieties. The project also involves using computer graphics techniques to render the generated plants.