To create a realistic dead appearance, you'll want to focus on paling the skin.
Nymphaea Alba Odorata Rosacea--A - od form coming near exquisita but more vigorous, with bright rosy flowers about 4 inches across, paling to salmon-yellow towards the crown of golden stamens; petals narrow and pointed.
Nymphaea Alba Robinsoni - A star-like flower of distinct color, a reddish-purple deepening towards the centre, which shows traces of an orange ground, paling again towards the tips of the petals.
Nymphaea Alba Lucida - With massive flowers opening starwise and rosy-vermilion in color, paling towards the edges and the tips of the petals and deepening towards the cluster of orange stamens.
Carnea - A noble hardy plant, in color a soft flesh-pink, deepening towards the base of the petals and paling gradually to white.