Hand-colored scanning electron micrograph (SEM) of the surface of a tomato leaf (Lycopersicon esculentum) created by Martin Oeggerli.
The picture is showing the complexity of a plant leaf area at invisibly small dimension. Scientists believe that the hairs and glands protect the plant against predators and reduce water loss through evaporation. Also visible are discretely grey-blue colored pores (stomata). They are responsible for the gaseous exchange: CO2 enters the leaf, while O2 and water are evaporated, thereby maintaining a constant flow of water from the roots, through the stem and branches, to the leafs.
Glandular trichomes are a special type of ‘hairs’ and contain crystals and oils in the bulbous section of the structures. Two of these structures can be seen in the picture. It’s believed that the crystals and oils are part of the plant’s defense mechanisms. The essential oils are responsible for giving the tomato plant its characteristic smell. The volatile compounds of the oils that contribute that contribute to the typical scent of tomato leafs are (Z)-3-hexenal, limonene, hexanal, (E)-2-hexenal, eugenol, 1,8-cineole, caryophyllene, beta-phellandrene, humulene, and linalool. It’s a little ironic that what might be considered intoxicating to us can be so “unpleasant” to pests! Collectively, these compounds are exclusive to tomato trichomes.