This cultivar comes
Marlene Ahlburg of Germany. It is a non-registered plant of unidentified origin . The leaves have little, if any, corrugation. Near-white flowers bloom from late June into July.
The Hostapedia by Mark Zilis (2009), "...sometimes incorrectly listed as 'Blaus Boot'...name
translates into "blue boat"."
Similar cultivars include H. 'Blue Angel'.