Book  (Oct 2001)  Page(s) 184-185.  Includes photo(s).
 
Clematis 'Evista'
Trade name: Evening Star
Raymond Evison (England)
Introduced by Guernsey Nursery 1997
Parentage unknown
... single, plum-mauve flowers... six to eight broad yet pointed tepals, which overlap when young, but as the flower matures the tepals tend to twist and the margins crinkle. Each tepal carries a cerise bar running lenthways and matched on the reverse by three purple-red veins... Late season flowers are not quite so large or numerous...