It is sort of difficult to id a clematis that is showing such unusual coloring. One of several things is happening. First, it could be a response to the weird weather we have had this year so far. I have had plants throw off weird colored and misshaped blooms in the past due to temp. vacillations. Secondly, you could have originally purchased a pot with two clematis in it. It does seem strange however that it took the plant(s) several years to bloom at all unless they were really immature plant(s) when you purchased them. Thirdly, you could have a plant that is sporting--a phenomenon where a plant develops a mutation that could lead to a new and different flower on a plant. Time will tell whether this phenomenon is repeatable year to year or if it is a one time thing. See the post entitled "The President" for a similar occurrence.

Thanks, I bought this at an end of season special for $1. It's in almost total shade, so that's probably why it didn't bloom. Or it may have had one or two purple flowers. I just noticed another bloom opening that seems a very light mauve. Very strange. I'm sure it's one plant because the different color blooms are on the same stalk. I'll keep an eye on it.