The Methods of Examining Oud: The Morphological, the Chemical, and the Genetic

When the question "what is the species of the tree of this oud?" is posed, many suppose that there is a single simple test that settles the answer. And the truth is that determining the botanical species is a precise scientific work, in which three main approaches complete one another — or compete: the morphological (the botanical, of the form), the chemical (the fingerprint of the compounds), and the genetic (the one that relies on the DNA). Each of them has what it reveals and what it is incapable of, and not one of them is a magical test that is carried out in the market on a piece of wood in the blink of an eye. In this article — which is the conclusion of the botanical guide to the species of oud trees — we explain these three methods at their general conceptual level: how each of them works in principle, and what it shows, and where its limits stand. And here we expand what we summarized in an overview of how the species of the oud tree is determined; for that article presents the whole picture, and this one descends to the methods themselves with a greater depth. And we affirm from the beginning our honest position at Oud Treasure: we do not carry out these examinations, and we do not possess a laboratory for determining the species.

1. Why we need multiple methods

If the distinction of the species of the oud tree were easy, we would not have needed more than one method. But the reality is that the species are many and close, and that what reaches the market of them is the resinous wood often — not the complete tree. And because each method has a window through which it looks upon a part of the truth and is blind to another part, it became natural that the scientists resort to more than one approach and compare between their results, instead of relying on a single decisive test.

There is, then, no "home test" nor a quick field examination that grants you the name of the species with certainty. Every method of the three needs conditions: a suitable material, tools or a specialized expertise, and a reference to compare against. And when any of these conditions is absent — which is what happens often with the cut, traded wood — the "determination" turns into a studied weighting, not a final verdict. And we explained this idea in general in how is the species of the oud tree determined?, and here we detail the methods one by one.

The aim of understanding these methods is not that you carry them out yourself — for that is the affair of the researchers and the laboratories — but that you know the limits of what can be known in the first place. For when you realize that science itself needs precise tools and strict conditions to name the species, you cease to await a certainty from a seller in the market who does not possess these tools, and you direct your trust to what can actually be verified.

2. The morphological method

The morphological method (morphology) is the classical botanical approach, and its basis is the examination of the form of the tree and its organs: the leaves and their shape and their venation, the flowers and their structure, the fruits and the seeds, in addition to the anatomy of the wood (wood anatomy) under magnification. The specialist compares these features with reference descriptions and specimens preserved in the herbaria to arrive at the attribution of the specimen to a particular species.

The strength of this method is that it is well established, and it does not necessarily need complex apparatus when the distinctive organs are available; for an expert eye and a lens may suffice at times. But its fundamental limit is that it works at its best on the living tree or its complete botanical parts — not on a piece of resinous wood cut far from its leaves and its flowers. And this is exactly what reaches the market: wood without the organs on which the classifier relies.

Therefore the morphology benefits the researcher who studies the tree in its habitat or examines a documented botanical specimen more than it benefits whoever holds a piece of oud in a store. And even with the availability of the parts, the distinction between the species that are extremely close — especially within the single genus — remains precise and subject to difference among the specialists. So it is a strong method, but conditioned by the material, and cautious in its results among the similar species.

3. The chemical method

The chemical method is founded on the idea of the "fingerprint": that each specimen has a composition of the volatile and resinous compounds that can be analyzed and a general pattern extracted from it. And among the most famous of what is mentioned in this context is the technique of gas chromatography coupled with mass spectrometry (GC-MS), which is used generally to separate the compounds in a specimen and identify their patterns. And the idea is that comparing these patterns may help to distinguish one specimen from another in a disciplined research context.

But an important caution is necessary here: the chemical fingerprint of oud is affected by many factors other than the botanical species — such as the geographical origin, the degree of the formation of the resin and its quality, any treatment the wood underwent, and even the method of taking the specimen itself. For the chemical pattern reflects these factors combined, and it is not translated directly into a "name of a species." And this makes it a tool for comparison and description more than a decisive verdict on the species by itself.

And therefore we remain here at the level of the concept without presenting particular lists of compounds, nor numerical attributions of precision, nor named studies; for those are details that concern the research laboratories and differ with the difference of the case and the method. It suffices that we understand that the chemical analysis shows patterns that may assist in the distinction when they are read with caution and a suitable reference, but it needs an expertise in the interpretation, and it does not offer — by itself — a certainty in the name of the species.

4. The genetic method

The genetic method relies on the DNA: the hereditary material is extracted from a suitable specimen, then segments of it are read and compared with reference databases to be attributed to a species or a genetic group. And among the concepts circulated in this domain is "DNA barcoding," and its general idea is the use of standard genetic segments as a kind of "code" that helps to distinguish the species from one another.

And the genetic approach is considered promising in principle because it looks at the tree at its deepest level, not at its apparent form which may be similar. But it is conditioned in its turn: it needs a valid material from which a sound DNA can be extracted, and reliable reference databases against which the reading is compared. So if the material is old or treated or degraded — as may be the case of much of the traded resinous wood — it may be difficult to obtain a sound reading or it may be impossible.

Also the precision of the result is contingent on the completeness of the reference databases and their correctness; for if the species is not represented in them a reliable representation, or the references themselves carry an ambiguity inherited from the reclassification — and it is a matter that touches the two genera Aquilaria and Gyrinops as we laid out in the difference between Aquilaria and Gyrinops — then the attribution may remain approximate, not decisive. Therefore we describe the genetic method as strong when its conditions are available, cautious when they are absent, and it is in any case the affair of specialized scientific laboratories, not the affair of the market.

5. The comparison table

The following table gathers the three methods in a single simplified picture: on what each method relies, what it reveals, where its limits are, and who uses it usually. And it is a cautious conceptual presentation, not a guide of procedure nor a table of numbers.

The table is a simplified and cautious conceptual presentation; the mentioned limits are general, and the details differ with the difference of the case, the material, and the laboratory.

You notice from the table that the common denominator between the three methods is the condition: all of them need a suitable material, a specialized party, and a reference for comparison. And when these conditions are available in a research context, they become valuable tools that complete one another. As for in the daily circulation of the wood, one of these conditions is often absent, which is what we move to in the following section.

6. Why the determination stays difficult on the traded wood

After reviewing the methods, a fundamental paradox becomes clear: the scientific tools exist and are capable, but the wood that reaches the market often lacks what these tools need. For the morphology wants leaves and flowers that are absent, and the chemical analysis is affected by the origin and the treatment more than the species, and the genetic examination needs a sound material and reference databases that may not be available for an old or treated piece. So the gap is not in the science, but in the material that reaches the hand of the buyer.

Added to that is that many of the oud species are close and overlapping, so even with the suitable material some distinction may remain difficult. And for this it is no wonder that the attribution of a piece to a particular species — relying on the wood alone — remains a cautious weighting in most cases. And we explained why the scent alone is not enough to determine the species in can the species of oud be determined from the scent of the wood alone?; for the nose judges the quality and the attractiveness, not the botanical classification.

And this structural difficulty is itself what explains much of the errors of naming in the market: when the scientific verification is difficult, it becomes easy for the pieces to be attributed to species according to custom or estimate or the commercial inheritance. And we detailed the causes of that — from the honest error to the deception — in why do errors occur in the naming of oud species?. So the conclusion is that the scarcity of the scientific examination in the daily circulation is not necessarily a negligence, but rather a natural result of the nature of the material and the difficulty of the availability of the conditions of the examination.

7. Our position and what it means for the buyer

We say it with a clarity in which there is no ambiguity: at Oud Treasure we do not possess a laboratory for determining the species, and we do not carry out morphological, chemical, or genetic examinations, and we do not claim the results of such examinations. This is a position we repeat because it is an honesty in which there is no shortfall; for the claim of what we do not possess betrays your trust, and we build our relationship with you on what can be verified, not on what dazzles.

And what do we do, then? We declare the origin and the grade clearly, and we evaluate the authenticity and the quality by the sensory means and the practical expertise — the look, the weight and the density, the scent upon heating, and the cleanliness from the filling and the manipulation. And these criteria are what we laid out on the page on how oud is sorted and examined, where we describe how we sort and examine before the sale, and we declare what we do not do as well.

And what this means for you practically: do not buy on the basis of a "claim of a laboratory" or a decisive botanical species name, for that is what is rarely verified in the first place. Buy on the basis of four tangible things: the disclosed origin, the declared grade, the scent that you test yourself, and the sample that you start with before committing. And we have gathered these practical rules in how to choose an authentic Indonesian oud, and they are complemented by the idea that the direct testing is better than every label.

And because the most truthful examination available to you is your sense, we invite you to start with a sample that you judge yourself before any commitment. And with this we have completed the axes of the botanical guide to the species; and for the complete picture return to the botanical guide to the species of oud trees, from which all the articles branch.