Every year, especially as summer sets in we get calls like this, people who have planted white or paler coloured flowering hellebore plants notice that their flowers are no longer white. As we speak I try to narrow the species of the hellebore in question down to species which actually open white. Even this can be confusing since many of the new interspecies hybrids have labels showing the flowers in various shades of pink or mauve and many people don't notice that these plants open white. Most people don't even know that these plants are very different from the Lenten Rose they think they bought.

    I swear people think I am not telling them the truth when I tell them that this is a natural occurrence. Often I explain that rather like Hydrangeas, the flowers change colours as they mature, but then I sometimes get asked what they can put on the plant to make it stay white or their preferred colour.

    With some people when I begin to explain that what we call hellebore "flowers" are actually sepals (or correctly, tepals) and will start to photosynthesize after it is fertilized I can see their eyes begin to glaze over. On the telephone there is that short period of dead silence that signifies total lack of comprehension. Rather like an automated call when you give an answer that is not in the program. It does not compute. 

     There are plenty of botanists on the web who can do a much better job in explaining why Helleborus sepals/tepals turn green. An excellent article that does so is titled Physiological and biochemical changes associated with flower development and senescence in so far unexplored Helleborus orientalis Lam. cv. Olympicus is. H. orientalis cv. Olympicus is the historic reference to the plants we call H. x hybridus.  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550562/

     So please don't think I am lying to you. :)