This is listed as "probably" a hybrid of
H. capitata x
which originated with
Gus Krossa and was registered by
Peter Ruh of Ohio in 1998. The plant grows to about 12 inches in height
with a spread of 33 inches. The medium green colored foliage is
slightly wavy and slightly rippled at the margins. Medium purple
flowers in dense clusters bloom from mid-July into August.
looks much like the species H. nakaiana, but the leaves start out
yellowish and turn green."