The Rubber Sapling (not to be confused with IndustrialCraft2's Rubber Tree Sapling) will grow into a Jungle Rubber Tree found naturally only in jungle biomes. Although Jungle Rubber Trees do not produce Sticky Resin, they can be turned into Rubber by putting logs into an Extractor. Crafting the logs produces Sticks instead of planks.
To grow, the sapling must be in the centre of a 3x3 dirt or grass patch. It may take as little as 10 minutes to over 1 hour (real time) to grow. Bone meal can not be used on this kind of sapling.