The Species of Trees That Produce Oud: Aquilaria and Gyrinops

Many know oud as a scent and a value, but few ask: from which tree does this precious wood come? The answer is that oud is produced mainly from trees belonging to two botanical genera: Aquilaria and Gyrinops, and both are spread in Southeast Asia. This guide is the botanical reference for the oud-producing trees in our store: we introduce the two genera and their most prominent species, and we clarify the difference between them, and the international framework that protects these trees, and how the species is determined scientifically — and why its determination remains a real challenge. We wrote it at Oud Treasure in an honest language: we mention what the sources support with reservation, and we do not invent geographical ranges nor scent descriptions nor a chemical composition that cannot be proven.

1. From which tree does oud come?

Oud is not a single botanical species, but an aromatic wood that forms inside particular trees. And what is known — and what the scientific reviews agree upon — is that oud is produced mainly from two botanical genera: Aquilaria and Gyrinops. And these trees are classified within the family Thymelaeaceae as is stated in the botanical sources.

And the general mechanism by which oud forms is one in the two genera: for the wood is in its origin pale, light, and of little scent, but it transforms — in response to the wounding of the tree and its infection with a fungal infection — into a dark, heavy wood saturated with an aromatic resin, which is what we call oud. This process we explained in detail in the complete oud guide, and it is the common denominator among all the oud-producing trees whatever their genus or species differs.

And the two genera are spread in Southeast Asia in general, with diversity in the geographical distribution between the regions of the region and its islands. Where exactly do the oud trees grow? This is what we detail in where oud grows, which draws the geographical map of the habitats of these trees.

And what is important is that we realize the difference between three levels that often mix: the genus (Aquilaria or Gyrinops), and the species (such as Aquilaria malaccensis), and the geographical origin (Kalimantan, Papua…). These three levels do not necessarily match, and the confusion between them is among the most frequent causes of ambiguity in the talk about oud, as we will see in the axis of the names.

And why the care for this botanical distinction in the first place, as long as the buyer does not buy by the Latin name? Because understanding that oud comes from specific trees, and that they are not a single tree but two genera and species, frees the buyer from much of the marketing illusions: for whoever knows that the species are close and difficult to distinguish is not deceived by a claim that is decisive about a rare species there is no way to prove. Knowledge here is an immunity, not an academic luxury.

2. The genus Aquilaria

The genus Aquilaria is the most famous and the most widely mentioned among the genera of oud trees, and to it are attributed many of the species that the oud market circulates. And it is — as the references mention — a genus of the family Thymelaeaceae, that includes tropical evergreen trees.

And in terms of distribution, the sources indicate that the species of Aquilaria tend to a wider presence in continental Southeast Asia and the western parts of the archipelago (such as the Malay Peninsula, Sumatra, and Borneo), even if this is a general direction, not a decisive boundary, since the distribution of the species overlaps and it is difficult to draw precise separating lines. And for whoever wants the linking between the botanical species and the geographical origin, where oud grows benefits him.

And this genus includes a number of species that we cover in this guide, among them Aquilaria malaccensis, Aquilaria microcarpa, Aquilaria beccariana, Aquilaria hirta, Aquilaria crassna, and Aquilaria cumingiana. And each of them has an independent article in the axes of this guide in which we review what the sources mention about it with reservation.

And we deliberately do not stick to each species a "scent fingerprint" or a specific chemical composition; for such attributions need a laboratory analysis, and they vary within the single species according to the environment, the infection, and the grade. What we say with confidence is that these species belong to the genus Aquilaria, and that they are among the oud-producing trees, and that distinguishing them one from another needs botanical expertise, not merely a look or a smell.

And among the mentioned species, Aquilaria malaccensis stands out as the name most repeated in the sources and the first to be included in the international protection, and Aquilaria crassna is mentioned for its association with continental Southeast Asia and its commercial standing there. As for the rest of the species such as Aquilaria microcarpa, Aquilaria beccariana, Aquilaria hirta, and Aquilaria cumingiana, they appear in the botanical reviews as among the species of the region, without that meaning that each of them is easily distinguished in the market. And this overlap between the species is a fundamental reason for the difficulty of determination to which we devote an axis later.

3. The genus Gyrinops

The genus Gyrinops is the second main genus that produces oud, and it is botanically close to Aquilaria within the same family. And some of what is classified today under Gyrinops was a subject of review and reclassification in the history of botany, which reflects the closeness of the two genera and the difficulty of separating between them.

And according to what the scientific reviews indicate, the genus Gyrinops has an important presence in eastern Indonesia specifically — in regions such as Nusa Tenggara and the eastern territories reaching to the range of New Guinea. And this association with the east of the archipelago is among the most prominent of what is mentioned about the genus, even if the precise boundaries of its distribution remain a subject of scientific detail. And this connects to what we know about Indonesian oud in general in the comprehensive guide to Indonesian oud, where this genus predominates in the eastern origins.

And among the species of this genus that we cover in the guide are Gyrinops versteegii, Gyrinops caudata, Gyrinops ledermannii, and Gyrinops salicifolia. And Gyrinops versteegii is mentioned as among the most repeated species of the genus in the sources, but we — here also — avoid attributing a scent or decisive characteristics to any of them, and we suffice with what the references support of belonging and general distribution.

4. The difference between the two genera

What then is the difference between Aquilaria and Gyrinops? Honesty requires saying that the difference is precise and botanical in its essence more than it is sensory. For the two genera belong to the same Thymelaeaceae family, and both produce oud by the same mechanism, and it is difficult for the non-specialist to distinguish between them by looking at the wood alone.

And the most prominent of what is mentioned of differences is the geographical tendency: for the species of Aquilaria tend to a wider presence in the continent and the western archipelago, while the presence of Gyrinops stands out in the east of the Indonesian archipelago — and this is a general direction gleaned from the reviews, not a decisive rule. As for the precise botanical differences (in the flowers, the fruits, and some anatomical features), their place is the specialized studies, and they are not relied upon in a quick field distinction.

And it is useful to note that the closeness of the two genera is not merely formal; for their classification witnessed reviews in the history of botany, and species moved between the two genera with the progress of the study. And this in itself is evidence that the boundaries between them are not sharp as may be thought, and that the botanical classification is a process that evolves, not settled once. Therefore we avoid decisiveness, and we suffice with what the scientific circulation has settled upon of the belonging of the ten species we cover to these two genera.

And what is important for the buyer is to realize that the difference between the two genera is not what he buys the oud upon; for distinguishing between them is a botanical matter, while the buying decision rests on the origin, the grade, and the scent as we will show. And we devote to the comparison of the two genera an independent axis in this guide in which we fulfill what can be said with confidence about the difference between them.

5. The oud-producing species

The following table gathers the species that this guide covers from the two genera: six from Aquilaria and four from Gyrinops. And it is an indicative, non-exhaustive list; for the oud species mentioned in the sources are more than that, and we merely chose what we address in detail in the axes of this guide. And everything in the distribution column is formulated in cautious expressions, and is not read as precise geographical boundaries:

And we reaffirm: the ranges mentioned above are indicative, built on what is repeated in the reviews, not on a field measurement that we conduct. And the purpose of them is to give a general picture of where each species is mentioned, not to be decisive about its boundaries. And for whoever wants the detail, let him follow the independent article of each species in the axes of this guide.

6. CITES and the protection of the species

The talk about oud trees is not complete without mentioning their international regulatory dimension. For according to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), oud trees were included in Appendix II of the convention, which is an appendix that regulates the international trade in the species to preserve their survival without preventing it entirely.

And the detail of that — as the convention mentions — is that the species Aquilaria malaccensis was included in Appendix II since the year 1995, then the inclusion was expanded to include the rest of the species of the genus Aquilaria and the entire genus Gyrinops since the year 2004. That is, all the species of Aquilaria and Gyrinops are today included in Appendix II of CITES. We attribute these facts to the convention as their source.

And the story of the inclusion of oud in CITES and its motives — from the pressure of demand on the wild stock to the efforts to regulate the trade — we addressed in the history of the CITES convention and oud. And the effect of that on the transformation of the industry from reliance on wild oud to cultivated we detailed in wild and cultivated oud.

And the practical benefit of this dimension: that the trade of oud across the borders is subject to documentation and regulatory compliance, and that the serious source commits to that. So when you buy oud, you are buying a product from species subject to international protection, and this makes the transparency of the source and the documentation an important criterion, not a marginal detail.

And it is good here to point out that the inclusion of a species in Appendix II does not mean the prevention of trade in it, as may be thought; rather it means regulating it so that it takes place within controls that ensure the exploitation does not harm the survival of the species in the wild. This balance between allowing the trade and protecting the species is the essence of the philosophy of Appendix II, and it is what makes cultivated oud — which relieves the pressure on the wild stock — a part of the solution, not the burden, as we show in the wild and cultivated oud article. We attribute this understanding to the framework of the convention as its reference.

7. How is the species determined?

A question that seems simple and its answer is difficult: how do we know that a particular piece of oud is of such-and-such species? The honest truth is that determining the species of the oud tree precisely is actually difficult, and it occupies the specialists themselves. For the species are close in shape (a clear morphological overlap), and often the oud reaches the market cut and treated far from the mother tree, so the clues that are relied upon in the botanical classification are lost.

And the sources mention three general methods for determining the species, varying in their precision and their requirements: the morphological method (examining the plant's formal features such as the leaves, the flowers, and the fruits, which are often not available in the cut wood), the chemical method (analyzing the compounds in the wood or the oil), and the genetic method (DNA analysis, which is the most precise but it is purely laboratory-based). And all of them are laboratory tools, not market ones.

And for this we warn against the claim of determining the botanical species by the look or the smell alone; for that is not possible with precision. What we commit to on the quality control page is examining the grade and the density of the resin and verifying the claims of the origin within the supply chain — not conducting a laboratory determination of the botanical species, nor do we claim that. This distinction is a part of our honesty: we examine what we are able to examine, and we are truthful in what we do not examine.

And a questioner may ask: does not the scent suffice to distinguish the species, as long as each species has its character? And the honest answer is that the scent is a weak indicator of the botanical species; for it is affected by the origin, the infection, the grade, and the manner of heating more than it is affected by the species alone, and two pieces of a single species may differ in scent, and two pieces of two species may be close. Therefore the determination of the species is not built on the smell, even if the smell is the master of the judgment on the quality of the oud and its character — which is a matter different from the botanical classification.

And we devote to this subject independent axes in the guide: an axis on the methods of determining the species, and another on the limits of relying on the scent alone in determining it, and a third on the tools of the morphological, chemical, and genetic examination in expansion. For the matter is deeper than to be abridged in a line, and its honesty is that it be said in it that the botanical certainty needs a laboratory, not an impression.

8. The scientific name versus the commercial

Among the most confusing for the oud buyer is distinguishing between the scientific name and the commercial or regional name. For the scientific name is binomial (such as Aquilaria malaccensis), a global botanical system that determines the species precisely. As for the names circulated in the market, they often point to the origin (Kalimantan, Papua) or to a trait or a character, not to the botanical species.

And the confusion between the two levels leads to a common misunderstanding: that a commercial or regional name is thought to be a separate botanical species, or that an oud is attributed to a particular species based on its origin only. And we have devoted to this matter the region name versus the species, which clarifies why the name of the origin does not necessarily match the botanical species.

And connected to this is another distinction: that the word "oud" itself is the name of the material in Arabic, and it is matched by Agarwood in English and Gaharu in Indonesia — and they are names for a single designation, not for different species, as we explained in the difference between Agarwood, Oud, and Gaharu. So the caution against confusing the name of the material with the name of the species with the name of the origin is necessary for a sound understanding. And we devote to the causes of the naming errors and to the difference between the scientific name and the commercial two independent axes in this guide.

9. Why it matters to the buyer

After all this botanical detail, a practical question remains: does one buy oud by its botanical species? The honest answer: not in the first place. For the botanical species stands behind the character of the oud and its rarity without doubt, but what you actually buy in the market is the origin, the grade, and the scent — and these are what you test and decide on the basis of.

For knowing that the oud is from Aquilaria or Gyrinops is a useful knowledge that deepens your understanding, but it does not settle the buying decision alone, especially since determining the species precisely — as we saw — is difficult in the first place. The more worthwhile thing is that you rely on what can be verified: from which origin the oud came, and which grade it is, and how you smell it yourself. And this is what we guide you to in how to choose an authentic Indonesian oud.

And because the scent is an experience that no scientific nor commercial name describes, the best thing to start with is a sample by which you test the origin, the grade, and the character directly. We provide for this the samples service, and a wider entrance to oud from its sources in the comprehensive guide to Indonesian oud. For the botanical knowledge illuminates your path, but the sense of smell is the final judge.

And this does not diminish the value of the botanical knowledge, but places it in its correct position: a tool for understanding and for protection from the claim, not a criterion for buying. For the seller who is decisive to you that a particular piece is of a specific rare species — without a laboratory analysis — goes beyond what can be proven; and the buyer aware of the difficulty of determination does not pay a price premium in exchange for a botanical claim that has no support. As for what deserves that you pay in exchange for it, it is a documented origin that a clear supply chain discloses, and an examined grade, and a scent you have tested yourself. By this the botanical knowledge integrates with the practical sense in a sound buying decision.

10. The complete axes of the guide

This article is the center of a wider botanical guide in which we cover each axis of the axes of the oud trees and their species in detail in independent articles. For what we reviewed above are conclusions aiming at the overview, while the detail belongs in the specialized articles. The following list is the complete map of the guide (eighteen axes); we build it gradually and link it here whenever each article is completed, so that this page becomes your gateway to the whole subject of the species of oud trees:

1. 1. What is the Aquilaria tree?An expanded introduction to the genus Aquilaria: its general features as the botanical references mention them, its habitat, and its standing as the most famous source of oud.
2. 2. What is the Gyrinops tree?An introduction to the genus Gyrinops close to Aquilaria, its presence in the east of the Indonesian archipelago, and what distinguishes it in the sources.
3. 3. The difference between Aquilaria and GyrinopsAn honest comparison between the two genera in the botanical closeness and the mentioned geographical distribution, and the limits of what can be said with confidence.
4. 4. Aquilaria malaccensisOne of the most mentioned oud species in the sources, the first to be included in CITES, and what is circulated about it with scientific caution.
5. 5. Aquilaria microcarpaA review of what the references mention about this species of a spread in the western archipelago, with the usual scientific reservation.
6. 6. Aquilaria beccarianaWhat appears in the botanical sources about this species, and the difficulty of distinguishing it in the field from its relatives.
7. 7. Aquilaria hirtaAn introduction to this species as it appears in the reviews, its mentioned range, and the limits of the available knowledge about it.
8. 8. Aquilaria crassnaA species whose association with continental Southeast Asia is mentioned, and its commercial standing, with the avoidance of decisive figures.
9. 9. Aquilaria cumingianaWhat the sources mention about this species of a presence in regions of the archipelago, in an indicative formulation.
10. 10. Gyrinops versteegiiAmong the most repeated species of Gyrinops in the references, and its mentioned association with eastern Indonesia.
11. 11. Gyrinops caudataAn introduction to this species as it appears in the botanical reviews, and its mentioned eastern range.
12. 12. Gyrinops ledermanniiWhat the sources mention about this species and its association with New Guinea and the eastern regions.
13. 13. Gyrinops salicifoliaA review of what appears about this species in the sources, among the eastern species of the genus.
14. 14. How is the species of the oud tree determined?An explanation of the methods of determining the species — the morphological, the chemical, and the genetic — and why the precise determination remains a real challenge.
15. 15. Can the species be determined from the scent of the wood only?An honest answer about the limits of relying on the scent alone in attributing oud to a particular botanical species.
16. 16. The difference between the scientific name and the commercial nameThe distinction between the binomial botanical name and the commercial and regional names circulated in the market.
17. 17. Why do errors occur in naming oud species?The causes of the ambiguity in naming the species: the morphological resemblance, the confusion of the commercial names, and the weakness of the documentation.
18. 18. The methods of morphological, chemical, and genetic examinationAn expanded look at the tools of distinguishing the species scientifically, and what of them is suitable for the laboratory not the market.

Until the building of these articles and their linking is completed, you find in the sections above a sufficient conclusion for each of them, with links to what we have actually published of related content on our blogs.

And finally, this botanical guide integrates with two other references on our store: if you want the introduction to oud in general and how it forms and everything connected to it, its place is the complete oud guide; and if Indonesian oud specifically draws you — its origins, its character, and its market — your destination is the comprehensive guide to Indonesian oud. And between this botanical guide and those two references the picture of oud with us is completed: a tree and a species, and an origin and a character, from the forest to the gathering.