Answer to the March's Horticulture Challenge

This unique flower is Diphylleia grayi also known as the Skeleton flower. It is a member of the Berberidaceae family, and it is closely related to other popular garden plants such as barberry and Oregon grape. When the rain stops, the water in the cells evaporates and the petals return to their original white color.
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Source: Davod Attenborough and Hasan Jasim