Notulae to the Italian native vascular flora: 20

In this contribution, new data concerning the distribution of native vascular flora in Italy are presented. It includes new records, confirmations, and exclusions to the Italian administrative regions for taxa in the genera Aethusa, Alchemilla, Astragalus, Avena, Carex, Centaurea, Centranthus, Chenopodiastrum, Crepis, Elatine, Filago, Gagea, Lamium, Lappula, Lisymachia, Nymphoides, Onobrychys, Plantago, Pseudopodospermum, Salix, Seseli, Stachys, Ulmus. A new combination in the genus Valeriana (V. pontecorvi) is proposed. Nomenclatural and distribution updates, published elsewhere, and corrigenda are provided as Suppl. material 1.