Meet the Asiatic dayflower (Commelina communis), which gets its name because the blooms last only one day. It is classified as a noxious weed in North America, but it is used as a medicinal herb in China, its native habitat.
According to Chinese folk medicine, it has febrifugal, antipyretic, anti-inflammatory, and diuretic effects. It is also used for treating sore throats and tonsillitis.
In Japan the flowers were used to produce a pigment in many world-renowned woodcuts from the 18th and early 19th centuries.