Book  (Oct 2001)  Page(s) 130.  Includes photo(s).
 
Clematis 'Black Prince'
Viticella Group
(C. viticella 'Black Prince')
Alister Keay (New Zealand) 1990... named by him in 1993
Chance seedling
... single, very dark claret-reddish black flowers... four broad, gappy tepals with recurved tips... maroon filaments and anthers... Flowers are borne on the current season's new growth...