According to Clematis on the Web, the introduction year is "c. 1900", which makes me think the "1599" here was a typo or misread of 1899.

http://www.clematis.hull.ac.uk/new-clemdetail.cfm?dbkey=580

:-)

Isn't there a mistake with the year of breeding? 1599 seems to be a bit early - Francisque Morel (1849-1925) can't be the breeder then ....