Agarwood, also known as aloeswood, eaglewood, or gaharuwood, is a fragrant, dark, and resinous wood used in incense, perfume, and small carvings. It forms in the heartwood of Aquilaria trees after they become infected with a type of mold called Phaeoacremonium parasitica. To fight the infection, the tree produces a resin. Before infection, the heartwood is light in color and has little scent. However, as the infection spreads and the tree releases more resin, the heartwood becomes dense, dark, and filled with fragrance. This wood is harvested and used in cosmetics, often called oud, oodh, or aguru. It is also known as aloes (not the plant Aloe), agar (not the thickening agent agar agar), gaharu, or jinko. Used for thousands of years, agarwood is valued in Hindu, Buddhist, Muslim, and Chinese cultures, especially in Middle Eastern and South Asian regions for its unique scent in perfumes, incense, and colognes.

Agarwood is rare and expensive because wild sources are declining. Since 1995, the international agreement to protect endangered species has listed Aquilaria malaccensis (a main source) in its Appendix II (species at risk). In 2004, all Aquilaria species were added to Appendix II, though some countries have concerns about this listing.

The scent and quality of agarwood depend on the tree species, where it grows, whether it comes from branches, trunks, or roots, how long it has been infected, and how it is harvested and processed. Agarwood is one of the world’s most expensive woods, along with African blackwood, sandalwood, pink ivory, and ebony. High-quality agarwood can cost up to $290,000 per kilogram, though lower prices occur when the wood or oil is mixed with artificial or immature materials. The quality of agarwood varies based on location, tree species, tree age, and which part of the tree the wood comes from.

History

The smell of agarwood is rich and pleasant, with few similar natural scents. In perfumes, it is known for mixing "oriental-woody" and "soft fruity-floral" scents. When burned as incense, the smoke has a "sweet-balsamic" scent and hints of vanilla, musk, and amber. Because of its unique fragrance, agarwood and its oil became important in many ancient cultures and religions. Over 3,000 years ago, the ancient Egyptians used agarwood incense during funerals. Ancient Indian texts called the Vedas, written around 1400 BCE, also mention agarwood as a fragrant material.

In the Hebrew Bible, the "Book of Numbers 24:6" refers to "trees of lign aloes," and "Psalms 45" describes a perfume made from aloeswood, myrrh, and cassia. In the Gospel of John, it is written that Jesus’s body was wrapped in linen with 75 pounds of aloes and myrrh before burial.

In the first century CE, a Greek writer named Dioscorides wrote about agarwood in his book De materia medica. He noted its use as incense and described it as having a bitter and astringent taste. However, people used it to freshen their breath by chewing it or holding a decoction in their mouths. Dioscorides also mentioned that a root extract was used to treat stomach issues, dysentery, and pain in the lungs and liver. Later, in the ninth century, the Islamic text Sahih Muslim and the Indian medical text Susruta Samhita also recorded agarwood’s medicinal uses.

As early as the third century CE, ancient Vietnamese texts, such as Nan zhou yi wu zhi (Strange Things from the South), described agarwood being collected in the mountains of what is now Central Vietnam. In the sixth century CE, Japanese records in Nihon Shoki (The Chronicles of Japan) mention a large piece of fragrant wood identified as agarwood, which was believed to come from Pursat, Cambodia. This piece of wood is still displayed today at the Nara National Museum in Japan, but it is shown only a few times each century.

Agarwood is respected in Hinduism, Buddhism, and Chinese folk religion.

Starting in 1580, after Nguyễn Hoàng took control of central Vietnam, he promoted trade with China and Japan. Agarwood was exported in three forms: Calambac (kỳ nam in Vietnamese), trầm hương (similar but slightly harder and more common), and pure agarwood. A pound of Calambac bought in Hội An for 15 taels could be sold in Nagasaki for 600 taels. The Nguyễn Lords later created a royal monopoly on Calambac sales, which helped fund their government. Trade records show agarwood was traded internationally as early as the thirteenth century, with India being an early source for foreign markets.

In the seventh century CE, writings from Northern India, such as Xuanzang’s travelogues and Harshacharita, mention agarwood products like "Xasipat" (a type of writing material) and "aloe-oil" used in ancient Assam (Kamarupa). This tradition of using agarwood bark for writing materials still exists in Assam today. In traditional Chinese medicine, agarwood is called Chén Xiāng (沉香), meaning "sinking fragrance." Its earliest recorded use appears in the Ming Yi Bie Lu (Miscellaneous Records of Famous Physicians), written by Táo Hǒng-Jǐng around 420–589 CE.

Etymology

The word "Agar" comes from one of the Dravidian languages, likely from Tamil, where it is written as அகில் (aghil).

Agarwood is known by many names in different cultures:

• It is sometimes called Lignum aloes or Aloeswood, which is not related to the plant Aloe. This name comes from the word "akil," through Hebrew and Greek languages.
• In Assamese, it is called xasi (সাঁচি).
• In Bengali, it is commonly called Aguru, the same name used in Sanskrit. In Bengali, the tree is called agor gach (আগর গাছ), and the oil is called agor ator (আগর আতর).
• In Odia, it is called agara (ଅଗର).
• In Malayalam, it is called akil (അകിൽ).
• In Cambodia, it is called chann crassna. The scent from this wood is called khloem chann (ខ្លឹមចាន់) or khloem chann crassna. In Khmer, "khloem" means "hard wood," and "chann crassna" refers to the tree species Aquilaria crassna.
• In Hindi, it is called agar, which comes from the Sanskrit word aguru.
• In Sinhala, the tree Gyrinops walla that produces agarwood is called "Walla Patta" (වල්ල පට්ට).
• In Tamil, it is called aghil (அகில்). However, ancient Tamil texts may have referred to a different plant, Excoecaria agallocha.
• In Telugu and Kannada, it is called Aguru, the same name used in Sanskrit.
• In Chinese, it is called Chénxiāng (沉香); in Korean, Chimhyang ( 침향 ); in Japanese, Jinkō (沈香); and in Vietnamese, trầm hương. All these names mean "deep scent" and describe its strong fragrance. In Japan, there are different types of Jinkō, with the highest quality called Kyara (伽羅). In Vietnam, ancient writings mention agarwood's use by traveling Buddhist monks.
• In Tibetan, it is called ཨ་ག་རུ་ (a-ga-ru). Tibetan medicine uses several types, including unique eaglewood, yellow eaglewood (ཨ་ག་རུ་སེར་པོ་), white eaglewood (ཨར་སྐྱ་), and black eaglewood (ཨར་ནག་).
• In Arabic, both agarwood and its oil are called oud ( عود ), meaning "rod" or "stick." This term is also used in Arab countries to describe agarwood. Western perfumers often use agarwood oil under the name "oud" or "oudh."
• In English-speaking Europe, it was called Lignum aquila (eagle-wood) or Agilawood, because of its similarity to the Tamil-Malayalam word aghil.
• In Indonesian and Malay, it is called gaharu.
• In the Philippines, it is called lapnisan.
• In Papua New Guinea, it is called "ghara" or eagle wood.
• In Thai, it is called mai kritsana (ไม้กฤษณา).
• In Laos, it is called mai ketsana (ໄມ້ເກດສະໜາ).
• In Myanmar (Burmese), it is called Thit Mhwae (သစ်မွှေး).

Formation

There are seventeen species in the genus Aquilaria, which are large evergreen trees found in Southeast Asia and South Asia. Nine of these species are known to produce agarwood. While all species can theoretically produce agarwood, it was mainly taken from A. malaccensis (A. agallocha and A. secundaria are other names for A. malaccensis). A. crassna and A. sinensis are the other two species commonly used for harvesting. The Gyrinops tree can also produce agarwood.

Agarwood forms over a long time in the trunks and roots of trees that have been damaged by an insect called the Ambrosia beetle, specifically Dinoplatypus chevrolati, first discovered by Stephan Alexander Peter. This insect feeds on wood and oily resin. The tree may then become infected by a type of mold, which causes the tree to create a special material to protect itself from damage. The unaffected wood of the tree is light in color, but the resin changes the affected wood’s color to yellow, orange, red, dark brown, or black. It also makes the wood much heavier and denser. In natural forests, about 7 out of 100 trees of the same species become infected and produce agarwood. In planted forests, people often infect trees with a fungus to make agarwood. This process creates a "damage sap" and is called "fake" agarwood.

Oud oil can be made from agarwood by using steam. From 70 kilograms of wood, the amount of oil produced will not be more than 20 milliliters.

Agarwood oil has a very complex chemical makeup, with more than 150 different compounds identified. At least 70 of these are terpenoids, which include sesquiterpenes and chromones. No monoterpenes have been found. Other common types of compounds include agarofurans, cadinanes, eudesmanes, valencanes, eremophilanes, guaianes, prezizanes, vetispiranes, simple volatile aromatic compounds, and various other compounds. The exact mix of these materials depends on the tree’s age, species, and the details of the oil extraction process.

Perfumery

Oud has become a common ingredient in perfumes. Many perfume brands create scents that include oud or mix oud with other chemical scent ingredients. Only a few perfume companies use real oud in their products. This is because oud is very costly and has a strong scent. Oud is usually used as a base note and is often combined with rose. Oud essential oil can be found online, but it is important to choose a reliable seller. Because oud is expensive, some products mix oud oil with patchouli or other chemical ingredients to reduce the cost.

Oud scent is widely used in the Middle East, the Arab world, and in Arab culture. It is used in many ways as a traditional fragrance and perfume. Oud also played a role in the development of ancient trade routes in the Arab region. It is popular among Muslims and has been traditionally used in mosques, where incense chips made from oud are burned.

The smell of agarwood oil is described as sweet, characteristic of agarwood, woody, balsamic, similar to sandalwood, leathery, fruity, smoky, animal-like, and like tobacco.

Aquilariaspecies that produce agarwood

The following types of Aquilaria make agarwood:

• Aquilaria acuminata, found in Papua New Guinea, Indonesia, and Philippines
• Aquilaria apiculata, found in Philippines
• Aquilaria baillonil, found in Cambodia and Thailand
• Aquilaria banaensae, found in Vietnam
• Aquilaria beccariana, found in Indonesia
• Aquilaria brachyantha, found in Malaysia
• Aquilaria crassna, found in Cambodia, Malaysia, Thailand, Laos, and Vietnam
• Aquilaria cumingiana, found in Indonesia and Malaysia
• Aquilaria filaria, found in New Guinea, the Moluccas, and Mindanao (Philippines)
• Aquilaria grandiflora, found in China
• Aquilaria hirta, found in Thailand, Indonesia, and Malaysia
• Aquilaria khasiana, found in Bangladesh and India
• Aquilaria malaccensis, found in Indonesia, Malaysia, Laos, Thailand, and India
• Aquilaria microcarpa, found in Indonesia and Malaysia
• Aquilaria rostrata, found in Malaysia
• Aquilaria sinensis, found in China and Laos
• Aquilaria subintegra, found in Cambodia and Thailand

• Sri Lankan agarwood is known as Walla Patta and is of the Gyrinops walla species.

Conservation of agarwood-producing species

Overharvesting and habitat loss harm some agarwood-producing species. Because of growing global demand for agarwood, the main species are listed on CITES Appendix II. This requires that international trade in agarwood be carefully monitored. Monitoring is done by TRAFFIC, a program run by WWF and IUCN based in Cambridge. CITES also requires that trade controls ensure agarwood harvesting and exports do not harm wild species.

In addition, agarwood plantations have been set up in several countries. These plantations were also introduced in countries like Malaysia and Sri Lanka as commercial crops. The success of these plantations depends on encouraging agarwood production in the trees. Many methods to stimulate this production have been developed, but their effectiveness varies.