Rubber tapping - a Para Rubber Tree / Parawood (Hevea brasiliensis). Bukit Lawang, Sumatra, Indonesia . Rubberwood plantation in a Sumatran tropical rainforest. Once, the trees are 5-6 years old, the harvest can begin: incisions are made orthogonal to the latex vessels, just deep enough to tap the vessels without harming the tree's growth. The sap is collected in a small bowl.