Strange clematis

This is a clematis I gave to my daughter last year when its' flowers were a beautiful pale lavender. This year the flowers are green- not complaining, we like them, but can anyone say what has happened?
:confused:

 

No-one is absolutely sure what causes this, but it is most probably due to a cold dry spring. The flowers normally return to their proper colour as the year progresses.

 

Ah. My pale pink and mauve ones were also very pale, though not green. Thanks, Palustris

 

That is interesting Palustris. I haven't seen that before in flowers, but what you said about the cold spring rings true. I have a Salvia atrocyanea, which is not very hardy but I grew it from seed sown in November in a light box. By the time it was about three foot high I had to put it outside, I had no more room. Some of its leaves went almost black in the early cold spell, as compared to its more recent pale green leaves. I assumed the black leaves were dead, but in fact they are absolutely fine and very healthy. Its just that they have this unusual dark pigment.

 

No info on Salvias, but the Clematis green flower thing is well documented in Chrisopher Lloyds books amongst others.
There is a Virus which has a similar effect, but then the flower is badly distorted as well and is obviously sick!