The product of a microbial fungal infection, agarwood is actually a fragrant, dark, resinous wood formed in the heartwood of trees of the genus Aquilaria.

Ancients have known about its medicinal healing properties long back, since 2000 years. Its oil has a musky, soft but defined fragrance that cater to healing, religious and aesthetic purpose. Tagged as one of the most expensive wood, it is widely used in perfume making, for flavor and fragrance. It is Aguru or the Agarwood. Even the lowest quality Agarwood can fetch arround 75000 rupees per kilogram.

The product of a microbial fungal infection, agarwood is actually a fragrant, dark, resinous wood formed in the heartwood of trees of the genus Aquilaria, which are native to the rainforests of Indonesia, Thailand, Cambodia, Laos, Vietnam, Malaysia, Northeast India, Bangladesh, the Philippines, Borneo, and New Guinea. When a tree is injured or infected with fungus, an immune reaction sets in, producing stressed-induced aromatic resins, called aloes, in its heartwood. Over the course of several years, the aloes slowly embed in the heartwood, creating agarwood.

There are many names for the resinous, fragrant heartwood produced primarily by trees in the genus Aquilaria. The commoner names include agarwood, aloeswood, eaglewood, gahharu, oudh. It is formed in the heartwood of Aquilaria trees, the plant species known as Aquilaria malaccensis.

The unaffected wood of the tree is light in colour. However, the resin dramatically increases the mass and density of the affected wood, changing its colour to dark brown or black. In natural forests, only an estimated 7-10% of the trees are infected by the agarwood fungus.

A large part of agarwood comes from wild plant. However, many local communities have come up with new techniques to artificially induce the generation of agarwood.. For instance, they cut a hole in the trunk or main branches of Aquilaria trees. If the wound is kept open by regular chipping, agarwood generation may be induced after several years and can be extracted in nominal quantities each time when chipped as long as the tree remains alive. Another technique takes the wounding a step further by plugging the wound with a piece of wood or pottery shard. This prevents the wound from closing and therefore would seem to be a more reliable method for inducing agarwood production.

Because of over exploitation, this species is in the verge of extinct and put in the red list of the International Union for Conservation of Nature (IUCN).