A piece of wood with a sweet, dry scent, used for furniture, craft pieces and ritual objects. The tree that gives it grows on limestone or granite above 900 metres, reaches 25 to 30 metres, and in Vietnam sits in a group with restricted logging.
A conifer of the limestone mountains
Pơ mu is a conifer, but its leaves do not look like needles. They are small and flat, 2 to 5 millimetres long on adult trees, set in opposite pairs on flattened branchlets so that they appear as whorls of four. The tree belongs to the cypress family (Cupressaceae), the same family as cypress, Texas cedar and hinoki.
The scientific name is Fokienia hodginsii. The genus Fokienia has only one living species. The genus name comes from the old romanised spelling of Fujian province in China, where the first specimen was collected and sent to Europe in 1908 by a Captain Hodgins. In English the tree is also called Fujian cypress.
Its range runs from southeast China to northern Laos and the north and centre of Vietnam: Hà Giang, Sơn La, Hòa Bình, Nghệ An, Hà Tĩnh and several other provinces. In Vietnam, pơ mu grows on limestone or granite terrain above 900 metres. It is a tree of the high mountains, not of the plains or the midlands.
It is a medium sized tree among large timber trees, 25 to 30 metres tall. Its wood is prized for furniture and craft pieces, and some mountain communities in Laos use it for walls and roofing. In Vietnam, the library records pơ mu wood from areas such as Phú Thọ and Yên Bái being used for crafts and ritual objects.
The very demand that makes pơ mu wood prized for those uses is also why the tree has become rare.
Precious wood and the question of origin
A 30 metre tree on a rocky mountain takes a long time to grow and a single day to fell. That gap is the root of every question about pơ mu. IUCN lists Fokienia hodginsii as vulnerable, and in Vietnam it is regarded as an ecologically threatened species.
According to the library page on essential oils of Vietnam, pơ mu is in group IIA of Vietnam's list of endangered, precious and rare forest plants. This group is restricted in logging and trade for commercial purposes. Pơ mu and agarwood are the two fragrant woods the library records as under protection.
For a bottle of essential oil, this means the source of the wood decides whether the bottle is legal, before scent even enters the question. The Siam wood page, carrying the international trade name for pơ mu oil, states the requirement plainly: use certified sources only. A bottle of pơ mu oil without papers for its wood is a bottle that cannot answer the first question.
The question of origin is not unique to pơ mu. In Japan, hinoki has been protected by the government since 1982. Hinoki wood is still on the market, but it comes from naturally fallen trees, from stocks felled before 1982, and from wood recycled from old buildings. Supply is defined by what already exists, not by trees still standing.
Pơ mu follows a similar logic. Fragrant wood does not vanish from the market when the tree is protected; it moves to sources that can be explained.
Distilling roots and wood residue
Pơ mu oil usually does not come from living trunks. The library records the oil as distilled mainly from roots and stumps left in the ground, together with shavings and sawdust. The library's origin data describe it more precisely: the oil is distilled year round from the shavings and sawdust of pơ mu at furniture workshops.
Botanical sources also note that distillation, especially of the root, gives an oil sold as Siam wood or pemou. Roots and stumps are the parts of the wood that hold most oil, and the parts that remain after the trunk has already been taken.
This practice has a practical meaning. Sawdust and shavings are by products of an industry that already exists; distilling them requires no further felling. The same holds for stumps left in the ground. Essential oil here is a way of recovering scent from what the timber trade left behind.
But residue does not automatically mean legal. Sawdust from illegally felled wood is still sawdust from illegally felled wood. The question of origin only moves back one step: not where the oil came from, but where the wood that made the residue came from.
The still does not know which store room a piece of wood came from. Only the paperwork does.
Nerolidol and the sweet wood scent
Pơ mu oil is almost entirely sesquiterpenes, heavy molecules that evaporate slowly. The two main constituents are nerolidol, about 30 to 45 percent, and fokienol, about 20 to 35 percent. The remainder includes alpha eudesmol from 3 to 8 percent. There is no significant light top layer.
Nerolidol is a sesquiterpene alcohol, formula C₁₅H₂₆O, molecular weight 222.37 g/mol. The library describes its scent as floral wood, lightly green, soft and sweet, recalling bark. It serves as a base note for many floral accords. Nerolidol occurs at high levels in cabreuva wood, 65 to 80 percent, and in the nerolidol chemotype of niaouli, above 90 percent.
Fokienol is the molecule named after pơ mu itself. It has been studied far less than nerolidol, and the library gives no separate scent description for it. What can be said is that the ratio between nerolidol and fokienol varies between samples, and together the two make up between half and four fifths of the oil.
The library describes pơ mu oil as warm wood, softly floral, close to sandalwood; the essential oils of Vietnam page uses the words dry and warm. On a blotter the oil opens slowly, sweet, with a very light floral line from nerolidol, then holds a dry wood base for many hours.
The closeness to sandalwood does not come from a shared molecule. Sandalwood carries santalol; pơ mu carries nerolidol and fokienol. Two different chemical paths lead to two soft wood scents that can sit side by side.
Pơ mu beside hinoki and Chinese cypress
Three Asian trees of the cypress family give three wood oils, and each follows its own chemical direction. Setting them side by side is the quickest way to place the scent of pơ mu.
Hinoki, Chamaecyparis obtusa, is a tree of Japan. Hinoki wood oil carries alcohols of the cadinane group: alpha cadinol about 20.5 percent, T muurolol about 18.4 percent, T cadinol about 10.6 percent, with gamma and delta cadinene. The library places hinoki in the Woody family; oil production is limited.
Chinese weeping cypress, Cupressus funebris, also named Chamaecyparis funebris, is a tree of central and southwest China; in Vietnamese it is called hoàng đàn rủ. The library records its oil as Chinese cedarwood. The main constituents are iso alpha cedrene at about 32 percent and thujopsene at about 21.6 percent, with cedrenol. The oil is produced in large volumes and is sometimes used to cut Virginian or Texan cedarwood oils.
Three trees, three sets of molecules. Chinese cypress follows cedrene and thujopsene, giving a dry cedar scent. Hinoki follows cadinol, giving a clean wood scent. Pơ mu follows nerolidol and fokienol, giving a sweeter wood with a floral line. Of the three, pơ mu is the furthest from cedar.
Within the Woody family, that places pơ mu on the soft side of the group, closer to sandalwood than to cedar. The same botanical family does not mean the same scent family.
Fragrant wood in a small bottle
A bottle of pơ mu oil is smaller than a hand but carries a whole chain: rocky mountains above 900 metres, a slow growing tree, a protection list, a timber workshop, a pile of sawdust, a still.
On safety, the library records pơ mu oil as a low risk for skin sensitisation, with no clear data on pregnancy. Nerolidol, the main constituent, is rated by the library as low concern; IFRA and the EU set no specific limit for it. There is no separate maximum dermal figure for pơ mu oil. Absence of data is a gap, not a guarantee.
The oil should be kept in a dark bottle, tightly closed, in a cool place. Because sesquiterpenes evaporate slowly, the scent of pơ mu oil changes little over a day, but a bottle left open for long is still affected by air like any other essential oil.
In perfumery, the library records pơ mu oil as a material of niche perfumery. It is not a high volume material like Chinese cedarwood oil. Limited supply and the question of origin keep it there.
The sweet wood scent of pơ mu is the easiest part of this story to describe. The harder part lies in the paper that travels with the wood.
The only species in its genus, on mountains above 900 metres.
The scent comes from nerolidol and fokienol. Legality comes from paperwork.
Every bottle begins with a piece of wood that has an address.