Mt. Olympus, the highest mountain in Greece, is a biosphere reserve and a magnet for countless visitors. In the wider area of Olympus, at least 1,700 species and subspecies of plants are recorded, 26 of which are endemic. Most of the endemics only occur in the high or subalpine zone, which is expected to be strongly affected by climate change or in specific microsites that might be affected by several other factors. Thus, the unique flora of the mountain will probably become extinct. Ex situ conservation can be utilized to prevent and even reverse this trend and preserve plant diversity for future generations. The aim of the present study was to develop reproduction protocols for the endemic species on Mt. Olympus, Centaurea incompleta, Centaurea litochorea and Viola striis-notata, to facilitate their mass production, either for ex situ conservation or reintroduction into their natural habitats, if necessary. Seeds of the target species were collected in summer 2021. In a sample of the collected seeds, the embryo viability was checked using sequentially 1% w/v tetrazolium solution and Evans blue solution concentration of 0.25% w/v. As for the germination tests, two treatments were used to terminate seed dormancy: (a) cold stratification at } 2 °C, and (b) imbibition in gibberellic acid (250 ppm) for 48 hours. The results showed that more than 75% of the embryos in the fertile seeds were viable. In the seed germination tests, treatment with gibberellic acid resulted in germination percentages for Centaurea incompleta and Viola striis-notata are equal to or very close to the seed viability percentage. In contrast, no treatment was successful for Centaurea litochorea, as the control germination percentage was higher.

In the Mediterranean Region, species of the genus Juniperus face conservation challenges due to human activities and climate change threats. Juniperus species are reported to present low regeneration rate, while their seeds often exhibit physical and physiological dormancy. Viability and germination of mature Juniperus excelsa seeds from population originating from the Prespa area (Florina, Greece), alongside with seedling survival were investigated to study the reproduction dynamic of species population known to represent a EU priority habitat type of limited distribution and with low regeneration rate. The seed cut test of an uncleaned seed lot revealed a high percentage of empty seeds (90.03%) and a low embryo viability (2%). Cleaned seeds were subjected to a total of 44 pretreatments, categorised into eight groups targeting physical and physiological dormancy, along with combinations of these techniques. Despite most treatments showing limited success in enhancing germination, three pretreatments exhibited promising results (germination between 22.22% and 39.40%). Subsequent germination tests involving these treatments in controlled chambers, as well as in field conditions, along with hydration-dehydration cycles, were conducted using newly collected seeds. Seed germination rates in controlled chambers remained low, suggesting a deep primary dormancy. Pretreated seeds, under controlled field conditions, passed two winter periods fully saturated, with 13 hydrating-dehydrating cycles in-between. Germination was maximised during the second year of the field experiment, reaching almost 100% after mechanical scarification for 6 sec., followed by immersion in 3% H2O2 for 2 h. However, seedling survival was low, reaching approximately 38.26%. The findings emphasise the challenges in germinating Juniperus excelsa seeds and highlight the importance of the optimised protocols for reforestation in order to conserve this habitat type.

Within the context of sustainable exploitation of phytogenetic resources, the present study aimed to develop species-specific seed germination protocols for eighteen native and potentially underutilized plant species originating from northeastern Greece. The taxa were selected based on their antioxidant potential and their provenance to enhance their regional exploitation potential, thus utilizing the species’ local adaptation traits. To quantify the maximum germination potential in each case, seed viability was assessed using the tetrazolium (TTZ) test. The pre-treatments applied for seed dormancy release included cold stratification and the application of gibberellic acid (GA₃) and kinetin. Germination tests revealed that 9 of the 18 species exhibited high germination percentages in the control treatment (ranging between 64 and 90%) indicating that after-ripening was sufficient for any seed dormancy release in a significant portion of the seed lot. Furthermore, cold stratification and hormonal treatments significantly enhanced germination in seven species (final seed germination up to 85%), indicating deeper physiological dormancy and confirming the role of cold stratification and phytohormones in dormancy release. Two species showed no germination under any pre-treatment while viable, indicating the presence of more complex dormancy mechanisms. Germination percentages were frequently lower than the corresponding seed viability values, which ranged from 70% to 100%, suggesting that a portion of the seed lot exhibited deeper dormancy throughout. The results showcased species with favorable germination patterns, thus successfully identifying species that can be readily propagated, as well as species that require specific pre-treatments. The study sets the basis for domestication and sustainable use of local antioxidant-rich flora, providing a clear roadmap for the agronomic utilization of the focal species to support the regional bioeconomy.

Urbanization reduces biodiversity and affects plant–insect interactions, creating a need for more functional green spaces. Urban meadows with native species are a promising option, but their use is still limited due to a variety of reasons concerning the utilization framework of suitable plant species. The present study aimed to develop seed germination protocols for 26 native Mediterranean herbaceous species originating from northeastern Greece selected to support the establishment of species-rich and self-sustaining urban meadows. To the above end, seed germination experiments were conducted ex situ under controlled environment conditions using seeds collected from the wild for each species. Seed viability was assessed using the tetrazolium (TTZ) test to determine the maximum germination potential in each case. Freshly collected seeds were stored under ambient conditions for approximately 3 months (after-ripening) prior to germination testing, which was followed by cold stratification as a pretreatment for dormancy release. The results showed high embryo viability in all species and indicated that most taxa exhibited either no dormancy or relatively shallow physiological dormancy. Germination tests revealed that 14 of the 26 species presented high germination percentages in the control treatment, which suggests that after-ripening contributed to dormancy release in a significant portion of the seed lot. However, it remains unclear whether freshly collected seeds require an initial after-ripening period before responding to cold stratification. Furthermore, cold stratification significantly enhanced germination in 12 species confirming its effectiveness as a simple and practical method for dormancy release. In addition to the seed germination results, the selected species present a wide range of functional and esthetic characteristics, including variation in plant height, flowering phenology and flower and leaf color. These traits are important for both ecological performance and visual quality in urban environments. The combination of extended flowering periods and color diversity suggests the potential for continuous floral resource availability, which can support diverse pollinator communities and, indirectly, urban fauna such as insectivorous birds. The results indicate that the studied species are suitable for biodiversity-oriented urban plantings. Their relatively shallow dormancy and ease of propagation, coupled with their functional and aesthetic traits, support their use in the development of resilient and self-sustaining urban meadows.

The Mediterranean region presents a significant number of plant species facing threats from habitat loss and climate change, particularly those with limited distribution and habitat scarcity, such as chasmophytes. The study represents the first investigation into the germination potential of Jancaea heldreichii (Gesneriaceae) and Viola delphinantha (Violaceae), shedding light on their seed dormancy characteristics and germination aiming to assist conservation efforts. Fruit capsules of both species were collected, and their seeds were either cold stratified or immersed in hormone solutions prior to a germination test. After the end of the germination test, the ungerminated seeds were subjected to a cutting test and those with a well-developed embryo were subjected to a viability staining test using two different dyes, 2,3,5-triphenyl tetrazolium chloride and Evans blue. The study revealed that hormone treatments, particularly gibberellic acid, significantly increased germination percentages (69.4% and 88.3% for J. heldreichii and V. delphinantha, respectively) compared to control (untreated) seeds. Kinetin also enhanced germination, with a significantly higher increase in J. heldreichii compared to V. delphinantha (50.1% and 6.4%, respectively), whereas cold stratification had a lesser effect (28% and 4.2%, respectively), and the control treatment showed negligible germination. An ungerminated viability test in both species revealed that in the gibberellic acid treatment no ungerminated seeds with a well-developed embryo (stained or unstained) were found, suggesting that all the seeds that could produce normal seedlings were germinated. The study underscores the importance of germination protocols for conserving chasmophytic endemics like J. heldreichii and V. delphinantha. Such protocols are essential for preserving these unique plant species and their habitats. Citation: Varsamis G., Merou Th., Tseniklidou K. & Tsiftsis S. 2025: Seed dormancy and reproductive traits of the southern Balkan endemic plants Jancaea heldreichii (Gesneriaceae) and Viola delphinantha (Violaceae). – Willdenowia 55: 67–77. Version of record first published online on 7 April 2025.

Deltas are highly susceptible to biological invasions because of strong hydrological connectivity, frequent disturbance, and intense human use. Here, we synthesise coordinated monitoring observations and literature evidence on invasive alien plant species (IAS) recorded in four Black Sea riparian protected areas located across five countries, surveyed under the IASON/IASON+ initiatives (Danube Delta, Nestos Delta and Lake Vistonida, Kızılırmak Delta, Chorokhi Delta and Kolkheti National Park). Across the study sites, 17 IAS were documented, mainly represented by taxa native to North America and characterised by high propagule production and/or strong vegetative regeneration. Woody riparian invaders (e.g., Amorpha fruticosa, Robinia pseudoacacia, Acer negundo, Gleditsia triacanthos and Ailanthus altissima) exploited nutrient-rich floodplain soils and disturbances. In contrast, annual weeds (e.g., Ambrosia artemisiifolia, Sicyos angulatus and Xanthium orientale) remained associated with disturbed habitat edges. Aquatic dominance was confined to the Danube Delta, where Elodea nuttallii and Elodea canadensis formed dense submerged stands. Species were assigned to broad range expansion categories (slowly, moderately and rapidly spreading species) based on project observations and supporting records. We discuss shared invasion syndromes linked to reproductive and dispersal traits and outline management implications for Black Sea deltas, emphasising pathway prevention, early detection and rapid response for localised taxa, and sustained control combined with restoration for dominant invaders.