What is the Aquilaria Tree? The Primary Oud Genus

When "oud" is said, most of what the market circulates comes from the trees of a single botanical genus that leads the scene: Aquilaria. For it is — as the scientific reviews agree — the most famous and most widely mentioned among the genera of oud trees, and to it are attributed most of the species that oud traders and lovers know. But what is this genus in the first place? To which family does it belong? And where is it spread? And why did it become "the primary oud genus"? In this article from Oud Treasure we introduce the genus Aquilaria a faithful botanical introduction: we mention what the sources support with reservation, and we do not invent numbers of species nor geographical boundaries nor scent descriptions nor a chemical composition that cannot be proven. This is an article from the axes of the botanical guide to oud trees; so if you want the more comprehensive picture, start from the guide to the species of trees that produce oud.

1. What is the Aquilaria tree?

The genus Aquilaria is a group of trees that belongs — as the botanical references mention — to the family Thymelaeaceae, and they are tropical trees whose homeland is tropical Asia. And the most important thing that distinguishes this genus in the context of our talk is that it is the primary genus that produces oud; for most of the oud circulated in the world is attributed to species of this genus, and for this its name became inseparable from every serious talk about oud trees.

And oud itself is not a botanical species, but a dark aromatic wood that forms inside these trees in special conditions. But the tree in its origin is an ordinary woody tree; for the aromatic resin does not exist in it from its inception, but rather forms in response to factors we review later. That is, Aquilaria is a botanical genus standing on its own, and oud is an occasional fruit that appears in some of its individuals, not an inherent trait in all of them.

And it is useful to fix three levels that often mix: the family (Thymelaeaceae), and the genus (Aquilaria), and the species (such as Aquilaria malaccensis). For the genus includes several species, and each species has its binomial scientific name that begins with the name of the genus. And there is — alongside Aquilaria — another genus that produces oud, which is Gyrinops, to which we devote an independent article; but Aquilaria remains the most famous and the most widespread in the market.

And why do we begin the botanical guide with this genus specifically? Because understanding Aquilaria is the key to understanding oud from its root: from this tree comes most of what you smell and acquire, and knowing what it is — and what it is not — frees you from much of the marketing claims. And to grasp the position of this genus among the rest of the oud trees and their species, please return to the botanical guide to the species of oud trees.

2. The form and the distribution

In terms of the general form, the trees of Aquilaria are described in the sources as tropical evergreen trees that grow in the rainforests. And we deliberately do not mention decisive numbers for their height or the diameter of their trunk; for such measurements vary between the species and the environments, and attributing a specific number to "the Aquilaria tree" in general is a defective simplification. It suffices us to say that they are trees of a tropical forest, medium to large in size as their description appears.

As for the distribution, the sources indicate that the genus Aquilaria has its homeland in South Asia and its Southeast; and its presence is mentioned in a range that extends from the Indian subcontinent and continental Southeast Asia to the western parts of the Malay archipelago (such as the Malay Peninsula, Sumatra, and Borneo). And this is a general direction, not a decisive boundary; for the distribution of the species overlaps, and it is difficult to draw precise separating lines, so we formulate it with the expression "it is mentioned," not with the expression of decisiveness.

And the linking between the botanical species and the geographical origin is a precise matter in itself; for the commercial name of the origin does not necessarily match the botanical species. And for whoever wants the geographical map of the habitats of oud trees in general — where they grow and why in those regions specifically — we detail it in where oud grows.

And what is important is that we realize that this wide distribution is one of the reasons for the primacy of Aquilaria; for its presence in a large geographical area of tropical Asia made it the genus most associated with the historical and modern oud trade, across the diversity of its origins and the difference of its environments.

3. Why Aquilaria is the primary oud genus

Aquilaria is often described in the sources as the "primary genus" for oud, and that returns — according to what is mentioned — to a group of converging factors, not to a single cause. The first of them is the wide geographical distribution to which we pointed, and the second is the abundance of the species attributed to it compared to others, and the third is its overwhelming presence in the oud market and its commercial history.

For from the commercial side, most of what is known and circulated of the scientific oud names returns to this genus; and Aquilaria malaccensis stands out in it as the name most repeated in the references and the first to gain the international protection, and Aquilaria crassna is mentioned for its association with continental Southeast Asia and its commercial standing there. This repeated presence in the literature and the market entrenched the image of Aquilaria as the primary source of oud.

But honesty requires pointing out that "primary" here is a relative description, not an exclusive one; for the genus Gyrinops produces oud too and has its important presence, especially in the east of the Indonesian archipelago. So the primacy of Aquilaria does not cancel the existence of others, but rather means that it is the most widely mentioned and circulated. And we avoid here decisiveness with numbers about its share in the global market, because such proportions are difficult to verify precisely.

And the conclusion is that the central standing of Aquilaria in the world of oud is a fact settled in the sources, but it is a standing of primacy, not monopoly. And knowing this balance is a part of the faithful botanical understanding that we seek in this guide.

4. The main species

The genus Aquilaria includes a number of species; and it is mentioned that the genus comprises dozens of species according to the botanical reviews, without our fixing a decisive number, because the numbers of the accepted species change with the progress of the study and the reclassification. So what we say with confidence is that they are "several species," not a specific number that we are decisive about.

And among these species is a group that stands out in the sources and in the oud market, which we single out with independent articles in this guide, among them Aquilaria malaccensis, Aquilaria microcarpa, Aquilaria beccariana, Aquilaria hirta, Aquilaria crassna, and Aquilaria cumingiana. And this is an indicative list of the most prominent of what we address, not an enumeration of all the species of the genus.

And each species of these species has a single article in which we review what the sources mention about it of belonging and general distribution, with the usual scientific 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. And to review these species all together in a single table alongside the species of Gyrinops, see the species table in the botanical guide to the species of oud trees.

And the reason for the difficulty of talking about each species separately is the closeness of the species themselves; for many of them are similar in shape difficult to distinguish in the field, so much so that the precise classification remains a challenge that occupies the specialists. Therefore we advise reading the articles of the species as a faithful presentation of what is mentioned, not a decisive separation between botanical identities easily distinguished.

5. Not every tree produces oud

Among the most important facts that many people are unaware of is that the existence of an Aquilaria tree does not mean the existence of oud. For the tree in its origin has pale, light wood of little scent, and oud does not form except in a minority of them that is exposed to a wound or a fungal infection that stimulates the tree to secrete a defensive aromatic resin, which is what we call oud. That is, oud is an occasional defensive response, not a fruit that every tree produces.

And for this an important commercial side of the truth is that the trees that produce oud densely and of value are a minority within the genus; for not every Aquilaria tree makes oud of a commercial value, but rather the one that was afflicted by the stimulus and the resin formed in it in a sufficient quantity and quality. And this alone explains the rarity of good natural oud and the height of its value.

And why do some trees produce oud rather than others, and what are the factors that govern that? We detail this matter in why some trees produce oud rather than others. As for the mechanism of the formation of oud itself — how the pale wood transforms into a dark wood saturated with resin step by step — we explain it in how oud forms.

6. Aquilaria and CITES

The talk about the genus Aquilaria is not complete without mentioning its international regulatory dimension. For according to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), Aquilaria 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 since the year 2004. That is, all the species of Aquilaria are today included in Appendix II of CITES. We attribute these facts to the convention as their source.

And the inclusion of a species in Appendix II does not mean the prevention of trade in it, as may be thought, but rather 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. And the story of the inclusion of oud in CITES and its motives we addressed in the history of the CITES convention and oud, and the effect of that on the transformation of the industry from wild oud to cultivated we detailed in wild and cultivated oud.

And the practical benefit of this dimension is 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 from Aquilaria, you are buying a product from species that enjoy international protection, and this makes the transparency of the source and the documentation an important criterion, not a marginal detail.

7. What does this mean for the buyer

After this botanical introduction, a practical question remains: does one buy oud by its genus or its botanical species? The honest answer: not in the first place. For knowing that the oud is from the genus Aquilaria is a useful knowledge that deepens your understanding, but the genus is a background, not a buying criterion. What you actually buy is the origin, the grade, and the scent — and these are what you test and decide on the basis of.

And the reason is that most good oud comes from this genus in the first place, so its name alone does not add a distinction between one piece and another; also determining the botanical species precisely is difficult and needs a laboratory, so the claim that a particular piece is of a specific rare species without an analysis goes beyond what can be proven. 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 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. So make the knowledge of the genus illuminate your path and protect you from the claim, and make the origin, the grade, and the experience the basis of your decision.