Cross between T. ackermannii and T. montanum done by Eugen Schleipfer of Germany. On my visit in 2007 he a had bunch of seedlings and he let me pick out the one I liked best. Now growing it for two years, I do like it a lot. Low growing mound of gray green foliage smothered with dark lavender-pink flowers throughout the summer. Naturally, we subsequently named that seedling "Eugen".