Abstract : The goal of this paper is the interactive and realistic rendering of 3D trees covering a landscape. The landscape is composed by instantiating one or more block of vegetation on the terrain. A block of vegetation is composed by a single or a compact group of trees. For these blocks of vegetation, we propose a new representation based on triangle+point primitives organized into a regular spatial structure (grid). This structure is defined onto easily adapt the level of details (LOD) of each subpart (cell) of the vegetation element. During the rendering process, we determine a global level of details for each block of vegetation. Then, we refine it for each cell according to the following heuristic: leaves or branches on the rear of tree or inside the forest are statistically less visible than front ones and then can be rendered coarsely. As a result, our method greatly decrease the number of rendered primitives by preserving realism. This allows rendering of large landscape in interactive time, for a camera far away until inside.