Oregano — The Genus Origanum (Lamiaceae): Taxonomy, Cultivation, Chemistry, and Uses by Tuncay Dirmenci, ed. New York, NY: Nova Science Publishers; 2022. ISBN: 978-1-68507-315-2. Hardcover, 462 pages. $270.00.

Species of the genus Origanum (Lamiaceae) are known commonly as oregano, and most are used as culinary spices or herbal tea ingredients. Some species, especially those with essential oils rich in carvacrol, a monoterpenoid phenol, have been used as ingredients in dietary supplements and traditional proprietary medicines. Many recent scientific publications have focused on the antimicrobial and antiviral activities of such oils. Oregano hydrosols, known in Turkey as Kekik suyu (“oregano water”), have been used as a remedy for gastrointestinal disorders and as a daily prophylactic drink for maintaining general health.

Tuncay Dirmenci, PhD, a reputable plant taxonomist from Turkey, edited this book, which is a welcomed contribution to the oregano scientific literature and covers most aspects of the genus Origanum. Turkey is the biggest exporter of oregano, followed by Greece and Mexico. In 2020, Turkey exported more than 20,000 tons of dried oregano herb worth more than $66 million and more than 100 tons of oregano oil worth approximately $9 million.

The book comprises seven chapters, with contributions from 19 authors, some of whom contributed to more than one chapter.

Chapter 1 covers the taxonomy of the genus Origanum, 90% of whose taxa occur in the Mediterranean region. According to the authors, Origanum has 42 species (49 taxa) and 22 hybrids. In my opinion, the number of species should be 43 with the addition of Origanum dubium, separating it from Origanum majorana. In his 1980 treatise on Origanum taxonomy,¹ Dutch botanist J.H. Ietswaart changed the status of O. dubium to be a synonym of O. majorana and kept this the same in his 1982 publication Flora of Turkey and the East Aegean Islands (Edinburgh University Press).² However, in R.D. Meikle’s Flora of Cyprus Volume 2 (Bentham-Moxon Trust, Royal Botanic Gardens, Kew, 1985), Ietswaart kept O. dubium separate from O. majorana, stating that O. dubium was an essential oil- and carvacrol-rich species,³ which was confirmed by molecular studies published in 2013.⁴ Except for this observation, the chapter is highly valuable.

Pollen morphology is covered in Chapter 2. Clear scanning electron microscope micrographs of Origanum taxa are accompanied by complementary pollen morphological data.

Chapter 3 gives valuable information on nuclear internal transcribed spacer (ITS) DNA regions of 40 Origanum taxa and 32 outgroup specimens. According to the author, genetic research suggests that Origanum is a monophyletic genus, meaning it is descended from a single ancestor. However, some sections of the genus are not monophyletic. The genus Origanum diverged from the related genus Thymus 5.1–6.5 million years ago, and Origanum diversified during the Pliocene epoch (ca. 3.05–5.33 million years ago). Additionally, biogeographic analysis suggests that the Eastern Mediterranean region is the center of diversity and origin of the genus.

Chapter 4 comprehensively covers the cultivation and harvest of oregano. This information is particularly useful for agronomists. Registered varieties of oregano are listed. The oil- and carvacrol-rich “Baser variety” of O. vulgare subsp. hirtum, named after this author, is also included.

Chapter 5 discusses the phytochemical constituents of Origanum taxa. Essential oils are considered the most important, and the tables summarize literature data in a comprehensible manner. Monoterpenoids, sesquiterpenoids, diterpenoids, triterpenoids, simple phenolics, flavonoids, steroids, fixed oils, and fatty acids are all covered in this chapter.

Chapter 6 includes information about Origanum biological activities. Main activities highlighted are antimicrobial, antiviral, antioxidant, anti-inflammatory, antispasmodic, antiproliferative and cytotoxic, enzyme inhibitory, insecticidal, antimalarial, antileishmanial, antiulcerogenic, and antiplatelet.

The last chapter, Chapter 7, reviews the traditional uses and commercial and economic importance of the genus Origanum. It also gives practical recipes and mentions landscape and architectural uses. The chapter also includes information about the global trade of oregano, traditional and modern techniques of the production of oregano essential oils and hydrosols, and other uses.

I highly recommend this book for spice traders, practitioners of phytotherapy and aromatherapy, pharmacists (especially pharmacognosists), agronomists, essential oil scientists and students, and those who wish to get up-to-date, comprehensive information on oregano and the genus Origanum.

K. Hüsnü Can Başer, PhD, is a professor of pharmacognosy at Near East University in Nicosia (Lefkoşa), Northern Cyprus.

References

1. Ietswaart JH. A taxonomic revision of the genus Origanum (Labiatae). Leiden Botanical Series. 4. Leiden, The Netherlands: Leiden University Press; 1980.
2. Ietswaart JH. Origanum In: Davis PH, ed. Flora of Turkey and the East Aegean Islands. Vol. 7. Edinburgh, UK: Edinburgh University Press; 1982:297-313.
3. Meikle RD. Flora of Cyprus. 2. London, UK: Bentham-Moxon Trust, Royal Botanic Gardens, Kew; 1985.
4. Lukas B, Samuel R, Mader E, Baser KHC, Duman H, Novak J. Complex evolutionary relationships in the Origanum section Majorana Benth. (Lamiaceae). Botanical J Linnean Soc. 2013;171:667-686.