The Hollong tree (Dipterocarpus macrocarpus) is a common perennial evergreen tree found in South-East Asia including India. It is the tallest tree of Assam and it has been recognised as the ‘State Tree’ for being the most dominant species in the forest. Hollong grows at elevation up to 610 m from sea level. In India,the Hollong flowers appear from June-July to November and the fruits ripen from January to March. The timber of this tree is used for veneer, plywood, paper pulp and charcoal. An oleo- resin, extracted from Hollong is used as a coat for waterproofing paper, as a varnish for boats, walls and furniture. The oleo- resin and the bark of the tree also have medicinal properties. This tree has a high demand in the shuttering and plywood sector, which has led to illegal felling in many parts. The Assam Government adopted Hollong as State Tree on 4th April, 2003.