This is the eighteenth of a series of miscellaneous contributions, by various authors, where hitherto unpublished data relevant to both the Med-Checklist and the Euro+Med (or Sisyphus) projects are presented. This instalment deals with the families Acanthaceae, Amaranthaceae, Araliaceae, Boraginaceae, Celastraceae, Chenopodiaceae, Compositae, Cruciferae, Cucurbitaceae, Cupressaceae, Cyperaceae, Euphorbiaceae, Gramineae, Grossulariaceae, Labiatae, Leguminosae, Martyniaceae, Orobanchaceae, Passifloraceae, Pedaliaceae, Plantaginaceae, Portulacaceae, Potamogetonaceae, Primulaceae, Proteaceae, Rubiaceae and Sapindaceae. It includes new country and area records and taxonomic and distributional considerations for taxa in Alkanna, Amaranthus, Cardamine, Carex, Celastrus, Centaurea, Chenopodium, Cyperus, Danthonia, Deschampsia, Dittrichia, Dodonaea, Euphorbia, Galium, Grevillea, Hieracium, Ibicella, Kalopanax, Metasequoia, Moluccella, Orobanche, Paspalum, Passiflora, Phelipanche, Phragmites, Portulaca, Potamogeton, Ribes, Ruellia, Salicornia, Salsola, Sesamum, Setaria, Sonchus, Thladiantha, Verbesina, Veronica and Vicia, new combinations in Bromus and a replacement name in Lysimachia.
