Asperugo is a monotypic genus native to many parts of Europe (but excluding Belgium). Its single species (Asperugo procumbens) has spread far beyond its native distribution range as a weed of cultivated fields. Nazaire & Hufford (2012) recovered strong support for the monophyly of Mertensia and the placement of Asperugo as its sister. Both these genera were strongly supported as members of Cynoglosseae.
Nazaire M. & Hufford L. (2012) A Broad Phylogenetic Analysis of Boraginaceae: Implications for the Relationships of Mertensia. Syst. Bot. 37(3): 758-783.