Dianthus cruentus Griseb. (Caryophyllaceae) is an herbaceous perennial native to Greece with a strong ornamental potential when used as a pollinator-friendly component of xeric gardens and green roofs, where it is valued for its tolerance of poor, dry soils, and its showy colorful inflorescences. Aiming to develop an efficient mass propagation protocol appropriate for the introduction of the species as a novel floricultural crop, the in vitro seed and clonal propagation of a Greek native xeric ecotype were investigated in this paper for the first time. A total of 90–100% of the seeds, after being stored in the dark at room temperature for 12 months, germinated when incubated at 10 to 25 °C after their surface sterilization and transfer in vitro. Sixty-day-old seedlings grown in vitro were then used as a source of nodal explants for the initial establishment of micropropagation cultures, more efficiently on MS medium with 0.1 mg L⁻¹ 6-benzylaminopurine (BA). In the multiplication stage, either normal or hyperhydric micro-shoots were used as explant sources, assessing the possibility of incorporating usually discarded material in the propagation procedure. Different solid media were tested, with the highest multiplication indices (5.1) recorded in an MS medium containing 0.1 mg L⁻¹ BA and 0.05 mg L⁻¹ NAA, regardless of explants’ hyperhydricity, while an MS medium containing 0.1 mg L⁻¹ BA and 12 g L⁻¹ agar proved optimal for the effective reversal of hyperhydric explants (MI: 5.2). Despite higher hyperhydricity and reaction rates being observed when hyperhydric explants were used, modifications in the multiplication medium proved to be highly effective in controlling hyperhydricity, with the highest number of normal shoots (2.4–2.6) produced in BA-containing media. Micro-shoots rooted readily in ½ MS medium (60–100%), with rooting rates and quality positively affected by the presence of 0.5 mg L⁻¹ IBA in the rooting medium and the absence of cytokinins in the multiplication one. Rooted micro-shoots were successfully acclimatized ex vitro at high rates (65–100%), their origin influencing their acclimatization and morphology. Thus, the concurrent use of normal and hyperhydric shoots in the proposed micropropagation protocol is proven to be both feasible and desirable, as it is able to significantly increase efficiency and facilitate the sustainable exploitation and dissemination of D. cruentus as a promising multivalent horticultural crop.

The introduction of new ornamental species is a challenge for the floriculture industry. Ebenus sibthorpii is an endemic species of Greece, with a strong ornamental potential. To the best of our knowledge, there are no studies on the in vitro propagation of this species. Therefore, the current study aimed to determine the possibility of micropropagation of Ebenus sibthorpii as a first step for its introduction into the floriculture industry. A preliminary study on the germination ability of the species was also conducted on 1/2-strength Murashige and Skoog medium (MS/2), in the range of 5–35 °C. Seeds germinated at 46–64% indifferently of temperature between the range of 10–30 °C. In vitro cultures were successfully established (77–80% explant response) from single-node explants excised from seedlings, on MS medium either hormone-free (Hf) or supplemented with 6-benzyladenine (BA) at 0.5 and 1 mg L⁻¹. The subsequent multiplication stage involved subcultures in MS medium either Hf or supplemented with various cytokinin types and concentrations, while the combination of 0.01 mg L⁻¹ naphthaleneacetic acid (NAA) with BA was also tested. Τhe highest multiplication indices (3.6–4.6) were observed in media containing BA at 0.1–0.5 mg L⁻¹, regardless of NAA presence, and in those with 0.5 mg L⁻¹ ZEA or 1 mg L⁻¹ TDZ. The highest number of shoots were formed in TDZ media, but almost half of them did not elongate. To address this, a two-fold culture was developed, where micro-shoots produced on TDZ media were transferred to Hf, MS or MS/2 medium to elongate. Thus, the highest multiplication index (16.4) was achieved when micro-shoots from 1 mg L⁻¹ TDZ medium were transferred to MS medium. The present study could be the basis of further exploitation and conservation of E. sibthorpii.

This study provides a comprehensive and refined framework for the micropropagation of the critically endangered Greek endemic Silene conglomeratica. Using a limited seed stock, a reliable in vitro propagation protocol was developed, supporting both ex situ conservation and potential commercial applications in floriculture and landscape architecture. Nodal explants excised from aseptic seedlings, established on half-strength Murashige and Skoog (MS) medium, were successfully used for culture initiation. Supplementation with 1.0 mg L⁻¹ meta-topolin (mT) and 0.2 mg L⁻¹ 1-naphthaleneacetic acid (NAA) promoted shoot proliferation. Subsequent subculturing on half-strength Rugini Olive Medium (OM/2) supplemented with 0.5 mg L⁻¹ 2-isopentenyladenine (2iP) resulted in high multiplication rates and a high frequency of spontaneous rooting. Rooting initiation was further optimized using OM/2 supplemented with 0.5 mg L⁻¹ indole-3-butyric acid (IBA). The high acclimatization percentage (80%) confirms the feasibility of this protocol for ex situ conservation and highlights its applicability for nursery production and specialized landscape use. Overall, this study contributes an efficient and scalable propagation strategy that supports both the conservation and sustainable utilization of this valuable endemic species. Future work should focus on refining these protocols through more targeted testing of concentrations and alternative combinations of growth regulators and nutrient compositions.

Lilium chalcedonicum L., a bulbous perennial endemic to the Balkans, is recognized for its considerable ornamental potential. In this study, seeds were gathered from a wild population and subjected to surface disinfection. Subsequently, they were placed in Petri dishes containing a half-strength Murashige and Skoog (MS) nutrient substrate (MS/2), with temperature conditions at 15 °C and 20 °C, followed by cycles of 5 °C and return to 15 °C and 20 °C, respectively. The in vitro-cultivated seedlings were then transplanted for further growth in MS medium enriched with either 30 g L^-1 or 60 g L^-1 sucrose and 0.1 mg L^-1 6-N-benzyladenine (BA). In the following stage, the resulting bulblets were separated and cultivated in MS/2, either without hormones (Hf) or with BA at concentrations of 0.2 mg L^-1, 0.5 mg L^-1, or 1 mg L^-1. Moreover, the combined influence of 1-naphthaleneacetic acid (NAA) at a concentration of 1.0 mg L^-1 and 0.2 mg L^-1 BA was examined. This stage was succeeded by a further division of the bulblets, and the explants were cultured in Hf, MS/2 or with the inclusion of 0.5 mg L^-1 BA or a combination of BA and NAA at ratios of 0.2/1 and 0.5/0.05 mg L^-1; zeatin at 0.5 mg L^-1 was also used, combined with 0.05 mg L^-1 NAA. Notably, all seeds exhibited a 100% germination rate following alternating temperature regimes including periods of low temperature. During the initial cultivation phase, each seedling gave rise to two bulblets measuring 0.6 cm in diameter. Subsequent subcultures on Hf substrates and those containing BA without NAA, resulted in the highest number of bulblets (1.6-2.2 bulbs/plant) of the largest diameter (0.8-0.9 cm). Particularly noteworthy was the substantial increase in the average number of produced bulblets during the subsequent subcultures (multiplication stage), where 16.9 bulbs were formed in MS/2 medium containing 0.5 mg L^-1 BA, with a median diameter of 1.7 cm.

Employing rare or threatened species in ornamental horticulture offers a dual benefit by promoting climate adaptation and enhancing species conservation. Kosteletzkya pentacarpos, an endangered halophytic species, holds potential for introduction into the nursery industry, but efficient propagation methods are lacking. The present study investigated the in vitro propagation of the species using nodal explants excised from aseptic seedlings. A two-stage in vitro culture system was tested with thidiazuron (TDZ) promoting shoot initiation at low concentrations, while higher levels induced callus formation. Transferring micro-shoots to hormone free-, Murashige and Skoog medium (MS) promoted the highest shoot multiplication and elongation. The effect of sodium chloride (NaCl) on in vitro culture was also assessed, with MS media containing up to 5.0 g L⁻¹ NaCl supporting successful culture establishment. Spontaneous rooting was observed during various stages of the culture process. Micro-shoots were rooted at 100.0% on half strength MS medium with or without indole-3-butyric acid, and all plantlets were successfully acclimatized in a peat–perlite substrate (1/1, v/v). Thus, the present protocol provides an efficient system for the large-scale propagation of K. pentacarpos serving as a valuable tool for its conservation and the potential use in the nursery industry.