Sherardia arvensis

About

Sherardia is a monotypic genus of flowering plants in the family Rubiaceae. The genus contains only one species, Sherardia arvensis, the (blue) field madder, which is widespread across most of Europe and northern Africa as well as southwest and central Asia and Macaronesia. It is also reportedly naturalized in Australia, New Zealand, Taiwan, Kerguelen, Ethiopia, Sudan, southern Africa, Mexico, Costa Rica, South America, Bermuda, Cuba, Haiti and much of Canada and the United States.

Summary from Wikipedia