From Dwarf Fortress Wiki
Rubber trees are a type of above ground tree. They can be found in tropical moist broadleaf forests. Like the overwhelming majority of overland trees, rubber tree wood is brown and produces brown products.
[PLANT:RUBBER] [NAME:rubber tree][NAME_PLURAL:rubber trees][ADJ:rubber tree] [USE_MATERIAL_TEMPLATE:STRUCTURAL:STRUCTURAL_PLANT_TEMPLATE] [BASIC_MAT:LOCAL_PLANT_MAT:STRUCTURAL] [USE_MATERIAL_TEMPLATE:WOOD:WOOD_TEMPLATE] [STATE_NAME:ALL_SOLID:rubber wood] [STATE_ADJ:ALL_SOLID:rubber wood] [PREFIX:NONE] [TREE:LOCAL_PLANT_MAT:WOOD][TREE_TILE:226] [PREFSTRING:branch shedding] [DRY] [BIOME:FOREST_TROPICAL_MOIST_BROADLEAF] [SAPLING]