Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel
Thank you to shotaku@Flickr from Missouri, USA for contributing today’s photograph (original via BPotD Flickr Group Pool). Much appreciated!
One will often find this cultivar under the (incorrect) names Clematis ‘Lanuginosa Candida’ or Clematis lanuginosa ‘Candida’. The Royal Horticultural Society points out, however, that Clematis ‘Candida’ should be used. The genes of Clematis lanuginosa are indeed found within this cultivar, but that species is one of two parents of this hybrid (the other being Clematis patens).

Wonderful photo. I love the high-res honoring of the real world details, the browning on the petal edges, the trellis, the browny thing resting on the flower. Captures the subtle interplay of translucence and reflectance of the petals perfectly.
Here in Vermont I’m enjoying the wild exuberance of our native ‘Virgin’s Bower’ Clematis virginiana.
Of the more than 30 clematis I grow in my Vancouver, BC, garden this is by far the best! It scrambles over a small magnolia and the numerous, very large, pure white flowers show up so well against its dark foliage.
I’m curious how the naming conventions work here. If I were forced to guess, I would have called it Clematis lanuginosa x patens — is there an authoritative treatment on when to name the hybrid parents and when to assign a new cultivar name?
Chris, the progeny of a cross between Clematis lanuginosa and Clematis patens are variable. There are a number of cultivars produced from these crosses, including Clematis ‘Candida’, Clematis ‘Aureliana’ and Clematis ‘Aureliana Superba’.
So, the question then becomes: why not use Clematis lanuginosa ×Clematis patens ‘Candida’ as the name? That configuration would cause confusion, I suspect.
As an aside, I’m guessing that the hybrid between C. lanuginosa and C. patens has never been scientifically named, otherwise something like C. ×thisisthescientificnameofthecross ‘Candida’ might be used.