Plant 366

Origanum species (Lamiaceae)


Origanum species, which are rich in essential oils, have been used by people for centuries as medicine, cosmetics and food flavouring. This genus of small-leaved, low-growing shrubs comprises about forty species distributed through Eurasia and North Africa, from the Atlantic Ocean in the west to the Pacific Ocean in the east. However, most species are found in the eastern Mediterranean.

Like Thymus (thyme), a related genus, Origanum species may be difficult to distinguish because of extensive variation within species and hybridisation between species. Marjoram (Origanum majorana) and oregano (Origanum vulgare) are important herbs, with different flavour characteristics, that are now found worldwide. However, when buying these herbs, the plants offered may include either of these species, Origanum onites, Origanum syriacum or interspecific hybrids.

The scents and flavours of Origanum species are associated with differences in the composition of their essential oils, for example, the proportions of chemicals such as pinene, camphor and especially carvacrol. Origanum vulgare, which is native to Britain and locally common in dry grasslands with calcareous soils, is distributed over much of the range of the genus. Over this range, it shows great variation in essential oil chemistry, and hence flavour of the plant.

In the mid-1780s, as he explored the eastern Mediterranean, John Sibthorp, professor of botany in Oxford University, identified wild-collected Origanum onites as a major trade item in the region. Moreover, he collected seed in Kórinthos for cultivation in the Oxford Botanic Garden. A century earlier, the English prelate George Wheler, who travelled in similar regions returned to England with seed of Origanum sipyleum, ‘a most beautiful kind of Origanum’. As Sibthorp taught botany in the late-1780s, he believed the plants he showed his students of this western Anatolian endemic were raised from the seed collected by Wheler.

Woolly-leaved Cretan dittany (Origanum dictamnus) is endemic to montane regions of the island, where it has been used for millennia. Classically, it was imbued with marvellous properties. For example, the Graeco-Roman physician Dioscorides reported that ‘goats fed on the herb reject arrows if shot’. Commenting on the habitat of Origanum dictamnus, Sibthorp stated ‘when growing wild it is remarkably more wooly than we here observe it in its cultivated State. Nature as the Sun darts its burning rays with considerable force in those Southern Regions seems to have furnished the Leaves of Plants to resist their force either with a thick coat of wool or down’.

Further reading

Ietswaart JH 1980. A taxonomic revision of the genus Origanum (Labiatae). Leiden University Press.

Lukas B et al. 2013. Complex evolutionary relationships in Origanum section Majorana (Lamiaceae). Botanical Journal of the Linnean Society 171: 667-686.

Stephen Harris