Thyme, wild thyme. For some they are synonyms, but the truth is much more beautiful and, as it usually is in nature, much more complex. None of our languages, especially in the context of folk names, have enough richness to describe all kinds of thyme genera, Thymus, as Latin language offers.
Today we will meet the species Thymus pulegioides. It is easiest to look at the stem and see how hairy it is and what shape it is. If it has four edges and is hairy only along the edges, it will be the species Thymus pulegioides. The species has several subspecies, so the leaves can be thicker or thinner, it can be more or less creeping, the calyx can be hairy or bare, so other elements are sometimes clumsy to identify. Thymus pulegioides is one of the species that we collect as “wild thyme”. The mixture we call wild thyme contains a number of species depending on the place of harvest.
The most fun part of the game with the genus of thyme, Thymus, is – smelling. Plants can have a variety of shades of scent, from lemony to geranium-like, and deep scents of the type Thymus vulgaris that you buy in teas and spices, and even a scent that is slightly reminiscent of oregano. Why? If you are not among the fans of biochemistry who know this, you may be surprised by the fact that all this bouquet of scents is due to acetic acid. Yes, it’s that salad acid. It is the first step, the starting material. The pathways of biochemistry are very diverse, but some are very similar between plants and animals, meaning they are more than a billion years old. The plant will turn acetic acid into oxaloacetate, a compound that we humans also make, especially when we are on a ketogenic diet or when we are hungry. This first step is the process by which the animals will create cholesterol. Cholesterol is typical of animals.
The enigmatic “Ediacaran biota” is a fossil trail of our oldest multicellular ancestors. The endlessly bizarre shapes in the fossils left countless doubts as to whether they were animals or plants or fungi. Cholesterol residues in some of the fossils confirmed the idea that animals are also in this group.
Plants have decided to go in a different direction than cholesterol. In the first step, the geranyl pyrophosphate compound is formed. Geranyl pyrophosphate is a big crossroads, a place where thymes decides how they will smell. The different scents of thymes are therefore called the dance of enzymes around geranyl pyrophosphate. Some will create a deeper scent reminiscent of a woody note of lavandin- that will be the scent of linalool. Some will create lemonene with a lemon scent to give it off. They may choose to cleave phosphates from geraniol-pyrophosphate and will release geraniol, the scent of roses and geraniums. It will combine acetic acid and geraniol and the scent will become even more similar to geraniums.
The dance of geranyl pyrophosphate can be genetically determined, but plants also leave space for epigenetics. Epigenetics has become an unnecessarily “tense” term, and it is easiest to translate it in one word – adaptation. With this dance, the plant will try to adapt to the microorganisms around them, and the pollinators, and the conditions in which it grows. This will be done by controlling the enzymes that are responsible for making the described compounds. In Croatia, Thymus pulegioides mainly contains geraniol and linalool.
A walk in the nature is a walk of all senses, the scents of different species of the thyme genera are the fun part of the walk.