When I paint flora, I like to put in little imperfections that are commonly found on the plant, including parts where an insect may have had a feed, growths that have developed on a leaf or flowers that are in the end stage and fading in colour before they drop off. In this case, the recently added flower is in that end stage and is, therefore, a little more dull compared to the rest. This can be evident even if it is in sunshine or, like this one, more in the shade. This is one of the reasons that I don't paint flowers in a still life. When a flower is cut it starts to die and, consequently, begins to change colour so, because of this you may not see the true colour or the differences between full bloom and fading because of natural attrition.