Palo santo: the importance of botanical names

I recently received an email that brought to my attention a common misperception that is deserving of attention. The email stated:

I am writing you as someone who enjoys and is interested in palo santo, specifically bursera graveolens. After reading that it was endangered in articles like yours, I stopped using it completely – actively campaigning against its use whenever I could.

However, after further research, I am starting to think there is some confusion. There are two species of palo santo, bursera graveolens and bulnesia sarmientoi. The links I provided are to the IUCN reports for each species. If you visit them, you can see that bursera graveolens is not actively considered an endangered species.

You are wrong – palo santo is endangered – but not all species of it. I believe that you are incorrect in listing bursera graveolens as endangered in your article. This confusion seems to be widespread.”

Firstly, it is critical to understand the importance of botanical names, a.k.a. scientific Latin names. Botanical names are universally recognized and help to reference plants in a number of fields. A botanical name such as Bursera graveolensbegins with the genus name (Bursera) followed by the species name (graveolens).

Botanical names are not functional in the same way as common names in that common names are not recognized universally and scientifically, and different species may be known by the same common name. For example, the common name ‘palo santo’ is used by locals in different geographic regions to describe two very different species Bursera graveolens and Bulnesia sarmientoi. Unlike a botanical name, common names have no bearing on the scientific differentiation of species.

Species differentiation takes many forms including they 1) fall under the same genus, or 2) belong to different genera. Take the genus Bursera for example – one species of Burserais graveolens (Bursera graveolens) and another is morelensis (Bursera morelensis)An example of two distinct species which belong to different genera is again Bursera graveolens (Figure 1) and Bulnesia sarmientoi (Figure 2).

Figure 1. Bursera graveolens commonly known as palo santo and holy wood. Photo credit: Maša Sinreih in Valentina Vivod – Own work
Figure 2. Bulnesia sarmientoi commonly referred to as palo santo, holy wood, and guaiacwood.

What confuses many people about these two distinct species is that they are both referred to ‘commonly’ as palo santo or holy wood. And just to add to the confusion, or rather to further clarify, Bulnesia sarmientoi is also referred to commonly as guaiacwood. So, although these two species share some common names they are vastly different. For example, Bursera graveolens essential oil consists primarily of limonene, menthofuran, and a-terpineol; whereas Bulnesia sarmientoi essential oil consists primarily of bulnesol, guaiol, and 10-epiy-eudesmol (see Tisserand and Young, 2014).

Common names lead to the kind of misunderstanding that can adversely impact how we support and perceive the conservation status of these species; therefore, always work from the standpoint of the botanical name. 

Bursera graveolens appears: 1) as near-threatened in Columbia on the International Union for Conservation of Nature and Natural Resources (IUCN) National Red List; 2) in a “vulnerability situation” in the Puyango-Tumbes river basin in the border region of Peru and Ecuador (https://www.iucn.org/content/education-needed-puyango-tumbes-river-basin); 3) as critically endangered in Peru by the 2005 Global Forest Resource Assessment (GFRA), which follows guidelines set out by the IUCN; 4) as critically endangered by the Food and Agriculture Organization of the United Nations in 2012; and 5) as vulnerable by the Darwin Foundation (Ecuador) (https://www.darwinfoundation.org/en/datazone/checklist?species=232).

Further, according to the 19th meeting of the Plants Committee of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (2011), Ecuador is planning to list this species under CITES Appendix III, whereby trade in these species is only permitted with an appropriate export permit and a certificate of origin from the state of the member country that has listed the species (https://www.cites.org/sites/default/files/eng/com/pc/19/E19-06-03.pdf).

Although statuses may have changed since their assessment date, unless there is absolute evidence stating otherwise, we advise working with the species as reflected by the most recent assessment in specified countries. 

Bulnesia sarmientoi is classified as endangered by the IUCN and is trade-protected by CITES. 

Also bear in mind that threatened and near-threatened plants are native and/or cultivated in more than one country. Regardless of location, it is highly advisable that when sourcing essential oil extracted from Bursera graveolens or Bulnesia sarmientoi that the growers/harvesters/processors  can demonstrate sustainable management through certification, particularly when sourcing material or oils from those countries where there is less stable infrastructure in place to protect the plant as evidenced by assessments done not just through the IUCN (global or regional), but also researched by other credible organizations.

It is also important to always have a good understanding of what part(s) of the trees are being used to extract essential oil or plant material for burning. Sustainable harvesting of trees includes extraction of the felled wood and/or branches, and there is evidence that the trees are being replanted. 

We have never advised people to stop using essential oils from these species; however, we encourage you to only do so if sustainable, ethical, and legal sources have been verified; whereby there is legitimate evidence that ethical wildcrafting is occurring, and for example in the case of palo santo – trees are being replanted. Sources like these not only help to protect threatened and near-threatened plants, but they also help to enrich communities, many of which represent Indigenous people who equally rely on these plants for their use in traditional medicine. 

However, it is equally important to represent the concerns around sustainable harvesting of palo santo as expressed for example by the Elemental Spirit Organization in the Costa Rica News – “People are consuming this product at a much faster rate than what can be produced by nature. It doesn’t matter if the wood you buy claims to be “sustainably” harvested or not. There are not enough naturally fallen trees to meet global demand!” – https://thecostaricanews.com/increasing-the-awareness-against-the-deforestation-of-the-palo-santo-tree/

Warmly,

Dr. Kelly Ablard

Reference

Tisserand and Young 2014. Essential Oil Safety: A Guide for Healthcare Professionals. 2nd Edition. Elsevier.