Helichrysum microphyllum subsp. tyrrhenicum (Asteraceae) is an endemic taxon of Sardinia and Corsica, where it grows at different altitudes. The objective of this study was to investigate the seed traits and germination behaviour of four Sardinian populations of this taxon located at different altitudes. Seed traits were evaluated, and germination tests were carried out by incubating seeds at a range of constant (5-30 °C) and alternating (25/10 °C) temperatures. The dry after-ripening (DAR) pre-treatment was also applied by storing seed in dry conditions for 3 months at 25 °C. Seed traits and germination behaviour data were statistically analysed to identify if there was a correlation with altitude. Differences in seed size, area and mass among populations were recorded, however, no relationship was found with altitude. High germination percentages were obtained in all populations, both in untreated and DAR seeds, and were positively affected by alternating temperatures. The final germination percentage and time required to reach 50% final germination (T ) showed no relationship with altitude. The differences in seed traits and germination detected among the studied populations of H. microphyllum subsp. tyrrhenicum were not correlated with altitude. This study provides new and important knowledge for this taxon. H. microphyllum subsp. tyrrhenicum is characterised by high germination percentages and low T values and does not seem to require any dormancy-breaking treatment. This species represents a high-potential native plant species that should be considered within environmental management plans.

Hypericum scruglii is an endangered endemic plant of Sardinia and the phloroglucinol compounds identified in this species have been reported to inhibit Human Immunodeficiency Virus activity. Seed banks are a genetic repository that effectively preserve taxa of conservation interest and they hold knowledge about the biology and germination eco-physiology of the taxa they preserve. The main goals of this study were to investigate the germination requirements of H. scruglii, to evaluate the seed viability after eight years of long-term conservation and to suggest an efficient protocol for germination. Seeds stored at -25 °C in the seed bank were tested at temperatures from 5 to 30 °C and 25/10 °C. Base temperature (Tb) and thermal time (θ50) for germination were estimated. H. scruglii seeds germinated over a wide range of temperatures, responding positively to high temperatures and 25/10 °C. Tb was estimated at 4.92 °C, and θ50 was estimated at 198.27 degree days. The high viability detected in seeds of H. scruglii allows us to suggest the use of seeds stored in a seed bank when fresh material for plant propagation is scarce. Our results provide new and useful baseline information for implementing conservation and multiplication strategies for this endangered medicinal plant.