Shrub to 2 m or so tall with large, white-tubed, violet flowers to 1.2 cm wide.
Raised in 1868 by H.W.Warren, nurserymen of Salisbury, UK, who found it growing as a self-sown seedling. Introduced to commerce by Cripps Nursery.
It is possible that other clones with bluer flowers are available under this name but more research is required to determine their origin.
Plants sold as Veronica lobelioides possibly belong here.