Silver-leaved nightshade, Solanum Elaeagnifolium, is  an alien: it is probably a native of S.W. United States and Mexico but has become a widespread, pernicious weed throughout U.S.A. and has invaded  all parts of the world with a Mediterranean climate.

 It has attractive narrow, silver-grey leaves and lilac flowers with prominent yellow stamens. The flowers are followed by orange-yellow berries: all parts of the plant are poisonous and, like all members of the  contain a number of potent pharmacologically active substances.   

Probably introduced as a garden plant, S. Elaeagnifolia has naturalised on the  upper reaches of Glisteri beach and on waste land close to Elios. The plant is intolerant of cold, wet conditions and Skopelos winters have probably limited its spread on the island. 

For more on Greek Alien Invaders go to Caprobrotus Edulis....