When immigrants arrive in a country with a different culture and language, the shock they experience is accentuated if they arrive in an unfamiliar biome.
Such is the case for immigrants who leave the chaparral of the Mediterranean for the temperate forests of eastern North America. There are a number of regions on the planet with chaparral, but their combined area still makes up the smallest but not least precious of all biomes. Chaparral is a coastal zone with hot, dry summers and cool, wet winters. In contrast, temperate areas have harsh winters and four distinct seasons. To keep the memory of homeland surroundings fresh, as soon as spring arrives in the Northeast, my relatives and I take out large pots of oleander, figs and rosemary—plants that could endure the winter of chaparral but which are killed by the deep frost of a temperate forest. Even in ancient times, rosemary was a token of constancy and remembrance, The symbol persisted in Elizabethan times–in Hamlet, his love, Ophelia, says, “There’s rosemary. That’s for remembrance. Pray you, love, remember.”
Rosemary’s name derives from Ros marinus, meaning dew of the sea. In its native regions, the perennial, evergreen shrub grows up to 2 meters in height. Its leaves, like the rest of its mint family-relatives, grow opposite of one another, and its stems have square cross-sections. But unlike those of basil and spearmint, rosemary leaves are narrow, bunched up and thick to endure light stresses and drought. Underneath each leaf, thick, green tissue lines the edges, but at the center there’s a characteristic thinner and white underbelly. Like the flowers, the leaves are rich in aromatic oils that perfume fingers just from gently rubbing them.
The composition of the oils is very sensitive to climatic conditions and thus varies significantly within the common species of rosemary, Rosmarinus officinalis. (Notice how the etymology has been preserved in the name of its genus.) In many cases, ecotypes have been established—in other words the varieties of rosemary producing different blends of essential oils have evolved and become genetically distinct. If moved elsewhere they would remain distinguishable from local varieties. In certain cases, one does not have to travel very far to see different ecotypes. In rosemary found in Cevoli, Italy, the compound 1,8-cineole—better known as eucalyptol— only makes up 6.6% of the essential oil and α-pinene is its main component. In Lunigiana, only 112 km away, 1,8-cineole makes up 37.9% of the oil and is the principal compound.
Perhaps because of the plant’s medicinal potential, it’s only recently (from 1993 to 2014) that comparative analyses have been conducted. Before we explore more geographical differences, let’s look at some of the interesting compounds that show up in rosemary oil, which includes three isomers of C10H16 and a pair of C10H16O.
Beyond Italy, we see again that 1,8-cineole is not always the principal component:
In fact just last year, a variety of rosemary cultivated in Sudan revealed a new chemotype, which is R. officinalis , chemical type bornyl acetate. As the name implies, the oil’s main constituent is the ester bornyl acetate. The only other samples with a high percentage of the ester had come from France, but in that case, the main component was still α-pinene, making the French sample a variant of the Cevoli-ecotype mentioned previously.
Last year a study found that rosemary essential oil prevented carbon tetrachloride-induced-increase of lipid peroxidation in the liver homogenates of rats. The researchers only tried a 1,8-cineole-chemotype, but the rest of the ratios found in the blend did not match any of the oils I’ve mentioned so far. It’s likely that their presumably Serbian rosemary oil does not have the same antioxidant properties as rosemary from different regions.
Whether we examine things at a molecular level or at the level of biomes, the variety of life on Earth is astonishing.