Aquilaria sinensis (Lour.) Spreng

Growth Form and Height

Aquilaria sinensis (Lour.) Spreng is an evergreen tree that grows 6 to 20 meters tall.

Bark and Wood Characteristics

It has smooth grayish to dark grey bark, and white to yellowish wood, which gives it the alternate Chinese name "Pak Muk Heung", meaning White Wood Incense.

Young branchlets are sparsely covered with hairs.

Leaf Shape and Dimensions

Its leaves are alternate, leathery, and obovate to elliptic, usually 5 to 11 cm (2.0 to 4.3 in) long and 2 to 4 cm (0.79 to 1.57 in) wide.

Leaf Vein Features

The leaves have 15 to 20 pairs of inconspicuous, nearly parallel lateral veins, a useful diagnostic feature for field identification.

Leaf Apex and Margins

Each leaf has a short acuminate apex, a broadly cuneate base, and entire, smooth margins.

Flower Characteristics

Its flowers are yellowish green, fragrant, and arranged in terminal or axillary umbels.

Fruit Morphology

The fruit is a woody obovoid capsule covered in short grey hairs, 2.5 to 3 cm (0.98 to 1.18 in) long.

Ripe Fruit Structure

When ripe, it splits open into two flat valves, and a silky thread from the fruit base holds the one or two seeds in place.

Species Distribution

Aquilaria sinensis is endemic to Southeast China, including Hainan, and occurs as an introduced species in Vietnam.

Primary Threat

It is currently threatened by habitat loss.

Agarwood Production

This tree produces agarwood, a valuable fragrant wood used in incense and medicine.

Historic Incense Use

Historically, its wood was used to make joss sticks and incense, but this industry has died out in Hong Kong.

Medicinal Resin Name

The resin produced and accumulated in the wood is a valued Chinese medicine called "Chen Xiang" (沉香).

Resin Induction Triggers

Chinese medicinal literature notes that large quantities of resin can be extracted after natural fungal infection or external wounding up to 5 cm deep into the bark.

Sustainable Resin Harvesting

To harvest resin sustainably, a 3 to 4 cm deep wound can be made in the bark, and resin is collected a few years later after it accumulates.

Alternative Resin Extraction

Small amounts of resin can also be extracted from wood blocks by heating or burning, which melts the resin and makes it seep out of the wood.

Commercial Wood Product

Trunk and branch sections that contain patches of fragrant, resinous wood are traded commercially under the name agarwood.

Resin Production Conditions

The plant is thought to produce resin as a reaction to fungal infection or external wounding, and resin-impregnated fragrant wood is typically found in trees over 20 years old.

Indiscriminate Harvesting

Not all individuals become infected, so rising harvest pressure has led harvesters in some regions to fell trees indiscriminately to find infected wood.

Traditional Chen Xiang Sources

High quality Chen Xiang was traditionally sourced mostly from the related species Aquilaria malaccensis and imported into China from Asian tropical regions, but supplies of this quality product are now depleted.

Additional Harvest Threat

Resin from Aquilaria sinensis is used as a substitute for this product, so Aquilaria sinensis is now also threatened as a result.

Ethnomedicinal Use

Aquilaria sinensis is a traditional medicinal plant of the Yi people.

Leaf Extract Laxative Effect

Its leaf extract has a laxative effect, caused by the chemical constituent genkwanin 5-O-beta-primeveroside.

Leaf Extract Biological Activity

Studies in mice have found that this extract shows activity against pain and inflammation.