Phylogeny and taxonomy of the genus Cinnamomum: what the study on plants from which cinnamon is derived clarifies

The main finding is that the Asian and Australasian species previously grouped under Cinnamomum did not appear as a single evolutionary branch. The Camphora section was closer to Sassafras, while the Cinnamomum section was closer to the African genus Kuloa. This means that the traditional name encompassed distinct evolutionary lineages, not that the plants lack common characteristics.

Analyses based on nrITS, either alone or associated with psbA-trnH, yielded five major groups. Leaf data provided additional support: the two groups differed in the outer wall of the epidermal cells. The authors therefore recognized Cinnamomum in a narrower sense and transferred 18 species to Camphora, including 15 new nomenclatural combinations. This is a taxonomic proposal based on available data, not a measure of the quality, aroma, or safety of commercial cinnamon.

Correct botanical identification is the starting point for speaking precisely about the plants from which cinnamon can be derived. If different species are referred to by the same genus or commercial name, it becomes more difficult to compare botanical descriptions, chemical composition, and materials examined in the laboratory. The study by Yang and colleagues therefore helps to clarify the boundaries between species and genera of the Lauraceae family.

The practical value is primarily classificatory. Phylogeny allows us to link visible similarity to evolutionary history, avoiding the mistake of considering plants equivalent simply because they have aromatic leaves or barks used in a similar way. However, an updated classification does not automatically identify the species of a powdered spice: for that result, documentary information or analytical methods applied directly to the sample are required.

The study used the largest sampling available for the group at the time of the analysis, but not all species had the same genetic data. In particular, Kuloa plastomes were missing. For this reason, the deeper relationships derived from chloroplast DNA may differ from those obtained with nuclear DNA. The authors themselves note that some relationships within the two main sections remain unresolved.

The results do not prove that all previous designations were useless, nor that a species transferred to Camphora loses its biological characteristics. They also do not demonstrate which species is contained in a specific food, extract, or supplement. Taxonomy describes relationships and scientific names; it does not, by itself, establish nutritional properties, health effects, or the characteristics of the product sold.

An anatomical analysis of 48 species has reinforced the idea that the two Asian lineages can be distinguished beyond their DNA. Gang and colleagues observed that specific details of the leaf epidermis, the surface layer of the leaf, followed the two phylogenetic groups [1]. This is indirect but convergent confirmation: the model consisted of leaves from botanical species, not commercial products. The limitation is that an anatomical trait, on its own, does not reconstruct the entire evolutionary history.

Yang and colleagues then studied two samples of Cinnamomum guizhouense using plastome and morphology. Both fell into the Camphora group, supporting the transfer of the species to Camphora guizhouensis [2]. This evidence is direct for that species, but it is not enough to verify all the reclassifications proposed in 2022.

A 2025 study compared plastomes and nuclear ribosomal DNA in 72 Lauraceae taxa, 35 of which are referable to Camphora and Cinnamomum. The nuclear DNA distinguished monophyletic groups—that is, branches with an exclusive common ancestor—consistent with the separation of the two genera [3]. The support is significant, but the authors themselves report differences between the genetic signals.

Not all analyses reconstruct the relationships between these groups in the same way. Rohde and colleagues, studying Neotropical species using molecular data and floral traits, transferred a set of plants previously attributed to Cinnamomum into the genus Aiouea [4]. The work confirms that the old perimeter of Cinnamomum was problematic, but it proposes a different arrangement for the American group than the one that emerged in Yang's study. The difference primarily concerns sampling and the position of the branches, not the use of phylogeny to revise names.

In a previous study on a single plastome of Cinnamomum camphora, Li and colleagues had placed C. camphora close to Cinnamomum verum within the same genus [5]. This outcome contrasts with the subsequent separation of Camphora, but it stems from a much narrower comparison. No directly discordant evidence of sufficient relevance was identified beyond these differences in topology and sampling; this does not prove the absence of contradictory results.