Germination behaviour of two endemic plants species in the South of the Iberian Peninsula: Cathissa reverchonii and C. villasina

Abstract The study of germination ecology of threatened flora is crucial to understand the requirements for developing effective conservation and recovery strategies. In this study, we investigated the germination response to temperature and light conditions simulating natural conditions for the Iberian-North African endemic Cathissa reverchonii (Lange) Speta and the narrow endemic C. villasina C.Salazar, Tercero & Mart.-Azorín. The aim of this study was to determine the optimal conditions for germination and evaluate the differences in their germination behaviour. Two preliminary sowings were carried out under semi-natural conditions and six germination tests were performed under controlled conditions with different temperature regimes in germination chamber. The results reveal that temperature is a critical factor for germination and highlight significant differences in the germination ecology of both species. While the more widely distributed endemic, C. reverchonii , lacks strict thermal requirements for germination, the narrow endemic C. villasina exhibits physiological dormancy, requiring cold stratification to alleviate dormancy. Our findings will allow the optimization of conservation strategies, providing significant value for the extremely restricted population of C. villasina. These divergent germination patterns, likely driven by ecological niche specialization, complement results from previous research on these related endemic species to support their classification as distinct taxa.