Agarwood

The formation of agarwood requires three conditions: the right tree species, the right location, and a special resinous reaction. All three are essential.

1. Agarwood Tree

【Family】Thymelaeaceae

【Genus】Aquilaria

In 1870, French botanist Pierre discovered a plant species on Phu Quoc Island in Vietnam and in the mountainous regions of Cambodia. The Cambodians named it "Krasna," which means "dark" in Sanskrit. Pierre applied for its official international scientific name and registered it as Aguilaria crassna Pierre, translated as "[Family Thymelaeaceae, Genus Aquilaria, Pierre species]." This marked the first formal announcement of the international scientific name for agarwood trees.

Trees from the families Oleaceae, Lauraceae, Euphorbiaceae, and Thymelaeaceae can all potentially produce agarwood. However, the highest-quality agarwood recognized by the public refers to the species from the Thymelaeaceae family originating in Southeast Asia, which is mostly referred to as such in the discussions by Cheng Xin Tang. From a botanical classification perspective, it belongs to the Thymelaeaceae family and the Aquilaria genus. Under the Aquilaria genus, there are numerous species, with over fifteen species registered internationally. However, not all species can produce agarwood. The following are some of the most important agarwood species:

1. Aquilaria crassna: Known as "Feng Shu" or "EagleWood" by the Vietnamese, it is found in the tropical rainforests of Vietnam and Cambodia. Another species, Aquilaria crassna Pierre, also known as "Singapore EagleWood," is found in Malaysia and Indonesia. It has a darker color, resembling gray-brown wood with subtle black lines resembling the wings of an eagle, hence the name.
2. Aquilaria malaccensis: This is the earliest species listed as endangered under plant and animal protection. Agarwood mentioned in ancient books such as "Deng Mei Liu" in Thailand's Sichon and "Fo Tai Ni" in Thailand's Pattani possibly belong to this species. It is distributed in Malaysia, Indonesia, and Kalimantan.
3. Aquilaria agallocha Roxb: This is a widely distributed agarwood tree, ranging from Bangladesh, India, Myanmar, Laos, Cambodia, to Vietnam.
4. Aquilaria sinensis (Lour.) Gilg: Also known as "Baimu Xiang" or "White Wood Fragrance," it is mainly found in Guangdong, Guangxi, and Hainan provinces in China. The high-grade ones can be used as medicinal agarwood, while the lower-grade ones, which have a faint fragrance in the heartwood and bark, serve as excellent materials for bedboards and cabinet interior partitions. When the wood is crushed into powder, it can be used as an additive for incense.

Agarwood trees can grow between 6 to 30 meters in height, with gray-brown bark and light yellow heartwood. The leaves are inversely ovate to elliptical, with alternate arrangement. They bloom in late spring and early summer. Agarwood trees are commonly found on slopes below 700 meters above sea level (ranging from 200 to 1200 meters), scattered in mixed forests, or clustered with five to six trees. According to "Tang Materia Medica," the leaves resemble those of oranges, remaining unfaded throughout winter, blooming white flowers in summer. In autumn, they bear fruits similar to betel nuts, purplish in color with a spicy taste. "Compendium of Materia Medica" describes the wood as similar to elm or willow, with greenish bark. The leaves resemble orange leaves, unfading throughout winter, blooming white and round flowers in summer. The autumn fruits resemble betel nuts, as large as mulberries, purple in color with a spicy taste. Different agarwood species may have slight variations in appearance.

Due to the increasing rarity of agarwood due to high demand, in 1995, the International Trade Research Organization for Wildlife (TRAFFIC) signed the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and listed Aquilaria malaccensis as an endangered species, imposing restrictions on its international trade to ensure the conservation of the species. As agarwood species are difficult to identify based on external appearance, in 2004, all species of the Aquilaria genus were included in the protected list.

2. The provenance of agarwood

Agarwood, also known as oud or oudh, is a highly prized aromatic wood. It is primarily produced in the tropical rainforests of Southeast Asia. The main countries known for agarwood production include Vietnam, Laos, Cambodia, Myanmar, Malaysia, Indonesia, and Papua New Guinea. In China, agarwood is produced in Hainan Island, Guangdong Province (particularly Maoming and Dianbai counties), as well as Guangxi, Yunnan, and Guizhou provinces.

Outside of mainland Southeast Asia, Indonesia is also an important agarwood-producing region. Different regions and countries have distinct characteristics in terms of agarwood fragrance. This is believed to be influenced by factors such as the porous nature of agarwood trees, the composition of the soil, air, rainfall, and microorganisms present in the environment. Agarwood is known to be sensitive to its surroundings, making the terroir (environmental factors) an important aspect of agarwood quality.

For example, agarwood from Vietnam, particularly from the Phu Quoc Island region, is highly regarded for its exceptional fragrance. Agarwood produced in central Vietnam, around Hue and Nha Trang, is known for its high-quality yellow agarwood. The border regions between Laos and Vietnam, often centered around Danang, serve as collection and distribution points for agarwood from these areas. This collective agarwood is referred to as "Hui An Chen," characterized by a sweet and cooling fragrance.

Agarwood produced in Malaysia, Indonesia, Borneo, Sumatra, and other regions such as Java, Kalimantan, Ambon, and New Guinea, is often collected and distributed in Singapore. This collective agarwood is referred to as "Xing Zhou Chen" and is characterized by its rich and penetrating fragrance.

In recent years, new agarwood-producing regions have emerged, including the boundaries of Kalimantan, Dalagan, and Brunei, as well as Manitol. The distribution of agarwood-producing regions is continually evolving and expanding. It is important to note that this overview provides a condensed summary of agarwood-producing regions and is not an exhaustive survey.

Due to the increasing rarity of wild agarwood and the threat to its survival, there has been a growing focus on artificial cultivation. However, naturally formed agarwood is highly prized for its quality and fragrance, with the process of resin formation taking many years. Artificially cultivated agarwood has a shorter growth and resin formation period, resulting in lower-grade wood with a less desirable fragrance compared to its wild counterparts. Furthermore, the safety and quality of agarwood produced through artificial methods, such as soaking in liquid, can be a concern if not properly regulated.

In conclusion, the future availability of high-quality natural agarwood, formed through the aging of decayed wood, will become increasingly rare and precious, akin to a rare and valuable treasure.

3.The process of agarwood formation can be summarized as follows:

1. 生 (Sheng) - Healthy Conditions: Agarwood trees require specific conditions for their growth, including tree species, soil, latitude, climate, and local environment.

2. 熟 (Shu) - Maturation: Mature agarwood trees do not produce fragrance naturally. They need specific factors to induce the formation of agarwood, such as physical trauma or external forces like lightning strikes, animal scratches, axe cutting, bark stripping, insect infestation, or fungal infection.
3. 虫 (Chong) - Insect Infestation: Insects, particularly a specific type of beetle known as the "agarwood borer," play a crucial role in the formation of agarwood. These insects bore into the tree, causing injury and stimulating the production of resinous compounds by the tree as a defense mechanism.
4. 脱 (Tuo) - Resin Accumulation: As a response to the insect infestation, the agarwood tree starts producing a resinous substance. This resin gradually accumulates in the affected areas, leading to the formation of agarwood.
5. 倒 (Dao) - Harvesting: After the agarwood has formed, it can be extracted from the tree through various methods. The tree may be left to naturally decay, or it can be intentionally felled and processed to extract the precious agarwood resin.

In the story mentioned in "隋唐嘉话" (Sui Tang Jia Hua), Tang Taizong asked Feng Ang, the leader of Gaozhou in Guangdong, whether his residence was far or near to the agarwood-producing region. Feng Ang replied that there were agarwood trees around his residence, but they only produced fragrance when they were rotten. However, this belief is incorrect. Agarwood trees need to be alive and healthy to secrete resin. It is only after agarwood has formed that the tree may appear rotten or decaying, leading to the misconception that only dead trees produce agarwood.

This story highlights the unique characteristic of agarwood, where healthy trees do not produce fragrance unless specific conditions are met. Expanding on Feng Ang's explanation, the "生" (Sheng) represents the conditions required for agarwood tree survival, such as tree species, soil, latitude, climate, and local environment. The "朽" (Xiu) represents forces that damage the tree, including lightning strikes, animal scratches, axe cutting, bark stripping, insect infestation, or fungal infection. When the necessary conditions for "生" are met, the agarwood tree grows healthily but does not produce agarwood. Only through the occurrence of "朽" and similar traumas, the agarwood tree secretes resin to protect the injured areas.

Some recent studies in China and abroad have discovered a potential relationship between specific fungi or mycelium and agarwood formation. However, the exact correlation between fungal species and the resulting fragrance is yet to be fully understood.

Therefore, the formation of agarwood can be described as a process of various injuries and decay:

(1) Live-formed: These are the agarwood formations that occur while the agarwood tree is still alive. They are caused by external forces such as axe strikes, animal scratches, insect infestation, or internal fungal infections resulting from injuries. The tree secretes resin as a self-defense mechanism around the wound, leading to the formation of aromatic resinous wood near the injury. These formations can be harvested while the tree is still alive. One of the external characteristics of live-formed agarwood is the traces left by the tools used by workers.

Sometimes, after the tree trunk has been cut off, if the roots are not completely dead and continue to secrete resin, it forms a covering structure known as "bao tou" or "bao ding" when it resembles a plate. When the tree crown is broken, it forms a structure similar to a seashell, known as "ke zi xiang." If the wood falls into the soil and is decomposed by the soil, it may also turn into mature agarwood.

(2) Dead-formed: These are the agarwood formations that occur after the agarwood tree has died. When the tree roots or trunk falls and sinks into the soil, over the course of years, the woody part is slowly decomposed, weathered, and contracted by microorganisms in the soil. This process leaves behind a solidified substance composed mainly of resinous components, known as "shu jie." The saying goes, "The wood is depleted, only the heart remains, the essence solidifies, and with time, it becomes powerful." These formations are often found at the roots of agarwood trees and appear as block-shaped or similar to the shape of the roots. They can be excavated from soil depths ranging from half a meter to one meter. After being unearthed, they are washed and excavated, hence the name "tu chen."

(3) Insect holes: These are the agarwood formations that occur due to the burrowing of insects into the wood. The shape of this type of agarwood is particularly unique and strange due to the tunnels created by the insects. Some formations even retain the shape of tree knots and insect holes, resembling natural sculptures. Most of the insect hole formations are live-formed, while a small number may mature when buried in the soil. However, without a doubt, they are all naturally formed, and their quality is generally good.

(4) Sheddings: These are the agarwood formations that occur when the resin accumulates between the tree bark and the heartwood, and the resin naturally peels off due to its weight. After the shedding, the wound continues to form agarwood, eventually leading to the detachment of the tree trunk, resulting in a secondary shedding. Shedded agarwood is usually found on the soil surface and appears as thin slices, often retaining the bark patterns.

(5) Fallen-formed: Also known as fallen agarwood or "dao jia zi" in the Minnan dialect. When the branches of the agarwood tree break and fall on the soil surface or are shallowly buried, some parts still retain the woody fibers and continue to live-form, while others undergo significant wood decomposition, turning into mature agarwood. Fallen-formed agarwood is a semi-live and semi-mature type of agarwood. It usually has a larger size compared to other formations.

(6) Heartwood oil agarwood: When the damage to the agarwood tree extends deep into the wood, the ample tree sap and nutrient-rich interior facilitate the formation of agarwood with a darker color and abundant oil content. This type of agarwood has thick oil lines, primarily composed of black oil. When the oil content reaches a

(7) Bark Oil Agarwood: If the wounds of the tree are limited to the surface of the bark and cannot reach the interior of the trunk, agarwood oil will travel along the conduits on the surface of the bark and adhere to the bark, forming thin slices known as bark oil agarwood. Bark oil agarwood is often thin in oil content and difficult to develop a strong fragrance. When heated, the oil quickly ignites. Bark oil agarwood can be divided into resin-discharging agarwood near the wood and bark-adhering bark oil agarwood.

(8) Top Cover: The name itself is intriguing and provides some insight when carefully pondered. Top cover refers to a layer of resin covering the top of the tree, and this thin layer of resin is called the top cover. In the original forest, when agarwood trees encounter storms with strong winds and heavy rain, tree branches are often broken. In the cross-section of the break, sap often surges upward and, after exposure to sunlight and rainwater, gradually solidifies into resin. Due to its exposed nature, it is easily discovered by agarwood hunters. The hunters remove the decayed surface wood and cut out a layer of resin-formed agarwood, which is the top cover. After being cut, it can continue to develop into a top cover after several years as long as the agarwood tree remains alive. Top cover agarwood has a short development time, insufficient fragrance, and generally average quality. Most top covers do not sink in water, making them suitable for making incense sticks or carved incense.

(9) Bao Tou: Some agarwood enthusiasts may be unfamiliar with this term. Chinese names often carry significant meanings, as the language is rich and profound. Bao Tou, like the top cover, can be understood to some extent through its literal meaning. Bao Tou refers to agarwood formed at a relatively flat break of the tree, which is then enveloped by new growth, resulting in Bao Tou agarwood.

Both Bao Tou and top cover agarwood are formed when agarwood trees have their branches broken by strong winds. Bao Tou is an upgraded version of the top cover, with the main difference being that the top cover is harvested shortly after formation, resulting in a lack of natural fragrance. Bao Tou is usually found in deep mountain forests, undiscovered by humans. After the break, the newly grown bark gradually wraps around the resin-formed part after hundreds of years of healing, eventually forming Bao Tou. In terms of the time taken for resin formation, Bao Tou generally has higher quality than the top cover.

(10) Ban Tou Agarwood: When the tree wound of agarwood forms a flat surface (usually caused by knife or axe damage or horizontal trunk breaks), a large area of the wound causes the tree to develop a thin but dense resinous body. This irregularly shaped and flat agarwood is called Ban Tou Agarwood. The resin lines in Ban Tou Agarwood are distributed in a dotted or flat pattern. Based on the density of the resin and the length of maturation, Ban Tou Agarwood is usually divided into three grades: "Tie Tou" (iron head), "Lao Tou" (old head), and "Ban Tou" (board head).

(11) Ke Zi Xiang (Shell Agarwood): Due to irregular injuries on the tree, a thin layer of shell-like agarwood forms. Shell agarwood usually has a shell-like appearance. The formation principle of shell agarwood is similar to that of Ban Tou Agarwood. However, due to the uneven cross-section and thin resin body, it acquires its distinctive shell shape.

(12) Yi Lou Agarwood: When the agarwood tree is still alive, parts of it are cut down by humans. When these parts fall to the ground and are then bitten by ants, the remaining oily parts are called Yi Lou Agarwood. Some professionals believe that Yi Lou Agarwood is a type of living agarwood, and it is not solely formed by ant bites. Other insects may also be involved. Although the tree is cut down, it still possesses some vitality and secretes tree sap and other substances. Some people consider Yi Lou Agarwood as "Chong Lou" (insect leakage). Before agarwood develops, it is already subjected to ant bites and damage. The bitten areas secrete some sap for self-protection. After combining with fungi and substances secreted by ants, agarwood formation takes place. Agarwood produced in this way has a particularly rich and fragrant aroma. Many people speculate that Qi Nan Agarwood is also formed after being eroded by insects and ants and then buried in the soil, resulting in only small patches of Qi Nan Agarwood in a large area.

(13) Tu Chen Agarwood: When trees naturally die or die due to natural disasters, the agarwood formed at the root or trunk of the dead tree that remains buried in the soil is called Tu Chen Agarwood (85% of Tu Chen Agarwood is formed at the root). After many years of decomposition and aging, the non-fragrant parts naturally decay, while the agarwood parts are preserved (agarwood is resistant to decay for centuries), resulting in Tu Chen Agarwood.

(14) Shui Chen Agarwood: It refers to agarwood trees capable of producing agarwood that fall and sink into water or marshland. Over several decades or even thousands of years, under the combined action of fungi and the resin of the tree itself, it develops into aromatic wood. Shui Chen Agarwood, because of its immersion in water, possesses an extremely mellow and profound aroma, unique and rich in layers. However, currently, the formation of Shui Chen Agarwood takes a long time and occurs accidentally, resulting in extremely limited production.

With the dwindling resources of natural agarwood and the high demand in the market, natural agarwood cannot meet the market needs. In recent years, the development of technology has led to rapid advancements in the technique of human-induced agarwood formation. There are several common methods that can stimulate agarwood formation in trees. The general mechanism involves damaging the main stem of the tree and stimulating the production of epoxy resin at the wound site.

human-induced agarwood formation:

1. Soft injury to the stem: Select mature trees and make two parallel cuts about 30 centimeters apart on the stem, at a height of approximately 1.5 meters from the ground, with a depth of around 4 centimeters.
2. Nailing the stem: Drive nails into the stem at a certain density.
3. Drilling holes in the stem: Drill holes in the stem at intervals of about 50 centimeters from the ground, with a diameter of 1.5 centimeters and a depth of approximately 6 centimeters. The spacing between the holes is about 15 centimeters, allowing them to penetrate through the stem.
4. Fire roasting the stem: Wrap the stem with cloth, pour automotive gasoline on it, and ignite it to burn the surface of the stem.
5. Partial or complete stem breakage: Make a rectangular incision on the stem at a height of about 1 meter from the ground, with a depth of approximately one-third of the stem and a width of around 4 centimeters. The incisions are spaced about 50 centimeters apart, and the opposite side of the stem can be shifted to compensate. Complete stem breakage involves cutting the agarwood tree at waist level, about 1 meter from the ground, and covering the cross-section with soil.
6. Organic chemical droplet damage: Drill a small hole in the branches and inject compounds into the tree through drip infusion.
7. Grafting method: After drilling holes in the stem, fill the holes with soil containing special fungal strains, and seal the holes with plastic film to prevent leakage.

However, so far, no matter how excellent the technique of human-induced agarwood formation is, the resulting agarwood quality is not ideal. The process of agarwood formation is a long journey that involves various injuries, inflammation, and bacterial interactions in the tree. High-quality agarwood requires several decades or even thousands of years to develop. Therefore, even with modern methods, it is difficult to replicate the unique and extraordinary fragrance of agarwood.