Micromorphological considerations on Alyssum nezaketiae Aytaç & H. Duman (Brassicaceae), endemic to gypsum habitats from Turkey: An electron microscopic study.

Alyssum nezaketiae is a local endemic species in gypsum habitats of Çankırı province in Turkey. In this study, I used field collected specimens of A. nezaketiae in a scanning electron microscopy examination of vegetative and reproductive structures of A. nezaketiae. The objective of the study was to investigate the micromorphological properties that define the species and that represent its adaptation(s) to the extreme environmental conditions posed by gypsum habitats. The epidermis had one to two rows at transverse sections of leaf and stem. Cortex was composed six to eight rows parenchyma cells at stem. A number of adaptations to xeric habitats were observed, including: dense silvery lepidote hairs on leaves and stems, small leaves, stomata on the lower surfaces of the leaves occurring in stomatal crypts, intense lignification in the central cylinder of the stems, and bundles of sclerenchyma in the pith region of stems. These can be interpreted as gypsophytic characteristics associated with physiological drought. Micromorphological properties of plant parts are discussed in relation to environmental conditions and possible constraint factors occurring in these gypsum habitats. Furthermore, these micromorphological studies contribute important taxonomic characters that are needed to help identify a species whose habitat is under threat from a variety of human activities.