The seeds, roots, leaves, flowers and fruits of the critically endangered (CR) species Saponaria jagelii Phitos & Greuter (Caryophyllaceae) were studied. The morphology of the seeds was investigated with scanning electron microscopy. The seeds were imbibed, germinated and developed into young plants. These plants, along with strictly selected wild-growing plants, were used for optical microscopic observations. The leaves and flowers were observed with scanning electron microscopy as well. At least two types of active glandular trichomes were detected on both the leaves and the calyxes of the flowers. The structures of the primary and secondary roots were also investigated. The roots turned into secondary structures very quickly and very close to the root tip. Light microscopy and histochemical reagents were employed to detect secondary metabolites of interest in the leaves. All the metabolites detected were already reported to be synthesized in stressed plants. Distribution data are presented. Conservation actions based on the habitat morphology and the human activities within it, such as the limitation of beach access during the seed-dispersing period and the prohibition of vehicle usage, are recommended in order to protect this tolerant yet severely stressed plant species.
Keywords: Saponaria jagelii; critically endangered plant; endemic plant; plant anatomy; seeds.