The presence of Euphorbia hyberna L. subsp. insularis (Boiss.) Briq. in the Ligurian Apennines. — The author studies the geographical distribution and the ecology ofEuphorbia hybernaL. subsp.insularis(Boiss.) Briq. in the Ligurian Apennines, where the plant occurs in several stations which are localized in two distinct areas: in the group of Mt. Dente (province of Genoa) and near the Capanne di Marcarolo (province of Alessandria).Euphorbia insularisis recorded only in Liguria, the Apuane Alps (Tuscany), Corsica and Sardinia. The climatic, edaphic, topographic and biotic characteristics of the stations in which the plant is found in Liguria are pointed out. It grows in different environmental conditions, but occurs only in localities with northerly or north easterly exposure, at altitudes between 700 and 950 m; it attains the best development in open places, like grassland and glades, where it grows profusely. On the whole,Euphorbia insularisrequires a climate characterized by a strong oceanicity, i.e. by moderate temperatures, a high amount of rainfall, and a notable atmospheric humidity throughout the year. However, the plant shows no particular edaphic requirements, and its occurrence on the serpentine soils is only due to the low competition in the plant-communities of these stations. The author emphasizes the remarkable phytogeographic interest ofEuphorbia insularis, which probably represents a tertiary atlantic relict and has survived in the Ligurian Apennines owing to peculiar geo-climatic conditions.