The rubber tree is a tree added by Industrialcraft2 as a source for Rubber. They spawn naturally, although they are rare, and can also be grown from a Rubber Sapling . Their trunks look like pine trunks with orange marks on them, but the leaves are normal colored. They are most common in Swamp biomes, but also spawn in Forests. An easy way to find these trees is to turn the graphics to fast. The rubber trees will still have leaves like the ones on fancy graphics.
UsesEditRubber trees often have one or more orange sapholes in them. If these are rightclicked while holding a Treetap , 1-3 Sticky Resin will pop out, and the hole will go dry and turn brown. After a few minutes, sap will return and it will turn orange again. If the tree is chopped down, it will drop Rubber Wood, and occasionally sticky resin and rubber saplings.
If you double right-click the saphole with a treetap you will defertilise it and it will no longer create new sticky resin.
In an extractor, one piece of rubber wood yields one piece of rubber, but with Equivalent Exchange, one rubber wood can be transmuted into one and one quarter sticky resin, which yields three rubber in an extractor. When possible, it is better to transmute rubber wood into resin as it roughly triples rubber yield.