This grower is sure of this plant identification.
A dark flowered form
Horminum genus (Pyrenean dead-nettle). This is a herbaceous perennial which will produce rosettes of glossy deep green, quilted ovate leaves from which rise stems of tubular or bell-shaped lipped flowers. They are fully hardy and will need sun and well drained soil. You can propagate by division in the spring or by seeds in the autumn.