This hybrid of Henckelia moonii and Henckelia walkerae was made by M. Yamagata. It is a free-ranging plant, and can grow quite large. The flowers are huge and attractive, but not produced in great profusion. A close-up of a flower can be seen here.
H. ‘Moon Walker’ is an excellent plant for a sunny window (where the plant in the photo above was grown) if room allows, or for a greenhouse. While it grows well under lights, it will soon crowd out everything else on the shelf. If the growing points are pinched out from time to time it will branch from the stems and from the base.