Xeromorphism of trichomes in Lamiaceae species

The xeromorphic adaptation of epidermal cells of Lamiaceae plant leaves, the conse­ quence of their adaptation to an arid habitat, was investigated. These xerophytic species inhibit transpiration in different ways, depending on the number, the form and the position of trichomes, whether they are dead hairs or live glandular structures. The Salvia genus is characterized on one hand by multicellular, uniseriate and scaled dead hairs and on the other hand there are several types of glandular structures, generally with voluminous heads. Lavender and rosemary (Lavandula angustifolia Mill, and Rosmarinus officinalis L.) have well-developed ramified forms of dead hairs with different ends and different levels of flexibility. The representatives of the Satureja genus have cone-shaped tri­ chomes, showing predominant glandular structures (with unicellular base, unicellular stalk and twelve-cell head) and a slight structural variation. While glandular trichomes are frequent in this genus, non-glandular trichomes are rare and few. In Salvia, although no glandular trichomes are developed, it has numerous simple, uniseriate, multicellular hairs. This is how the leaf epidermis, by xeromorphic changes, ensures the preservation of the entire plant.