Beyond appreciating them in cooking, what are oyster mushrooms good for? Pleurotus varieties are saprotrophs that are involved in providing nutrition to its ecosystem as a primary decomposer of wood, especially deciduous trees, and beech trees in particular, though here in the Pacific Northwest, oyster mushrooms are also seen growing on dying hardwood trees. Their saprophytic function benefits the forest by returning vital elements and minerals to the environment in forms that are usable to other plants, other organisms, and general soil biology.