In the application in agriculture and forestry of modeling and simulation of three-dimensional plant growth, interactive visualization of virtual plant community using recently developed model processing and model simplification technology in computer graphics and virtual reality becomes a new focus. The new methods in this paper are the simplifications of models with special shapes: Progressive Leaves Union and View-Dependent Branch Mesh Reorganization, where the originalities include: (1) topological structure modifying progressive simplification with error analysis for sparse parts of a plant, i.e., leaves, flowers and fruits; (2) multi-resolution remeshing for continuous parts, mainly branches; (3) simplification degree determined by viewpoint position, permitted errors, display resolution, and different positions of plants. Therefore, plant models with high proportional simplification are obtained keeping original visual effect within permission scope. Plant modeling and the growth simulation methods in AMAP team are used and plant-positioning data are generated from software AMAP-OrchestraTM as data source. An interactive navigation in virtual orchard is accomplished, and a virtual apple orchard is presented as an example. All of this work is taken in the organization and environment of the high performance computation and visualization in ISA and SILVES projects of INRIA.