Investigation of seed germination of twelve Mediterranean wildflowers for evaluating their potential use on extensive green roofs.

The use of native plants in an urban context can have positive impacts, such as the reduction of water requirement, management costs, increasing urban biodiversity, and the safeguard of germplasm. This study evaluated the germination capacity of twelve native Mediterranean wildflowers aiming to be utilized for extensive green roofs. Some of the taxa (Antirrhinum majus subsp. tortuosum, Dianthus sylvestris, Lobularia maritima, Ruta chalepensis) have not been previously investigated. Seeds of native plants were collected in Italy, and quantitative analyses on seed germination in light or darkness conditions were carried out. For every taxa, mean germination time (MGT) and germination percentage were determined. The taxa differed markedly in their germination percentage and times. The results were generally concordant with previous research, and in particular for Armeria pungens, Clinopodium nepeta and A. majus. However, some differences were also observed for Helichrysum italicum subsp. microphyllum and Prasium majus, and distinct differences for Anthemis maritima and Glaucium flavum. Finally, A. majus, D. sylvestris and G. flavum (in darkness) showed high germination percentage, low MGT and limited requirement of pre-seeding treatments. Further research is needed to assess germination performances and success while scaling-up from laboratory to greenhouse to outdoor field conditions.