[From
An Abundance of Flowers, by Judith Taylor, 2018, p. 157-158:] Kazushige Ozawa (d. 2003) ...used the small-flowered North American species for a very specific purpose, adding C. integrifolia to increase the size of the individual flowers. Practitioners of the Japanese tea ceremony like to have a single clematis flowerin a vase on the table to enhance the ritual, and Ozawa set out to breed long-stemmed, rich yet subtly hued flowers with interesting shapes for that purpose...
