The sizes of the coins were reduced in 1991 thus the Flora Fauna Series was renamed Improved Flora and Fauna. Along with this improvement was the introduction of 5-piso coin to replace the 5-piso banknote and save on the cost of printing considering that 5-piso banknote was the most widely circulated denomination. Other denominations of the Flora and Fauna such as the 50-, 10-, 5- and 1-sentimo were not anymore improved. This series together with the 10-centavo English, all denominations of Pilipino, Ang Bagong Lipunan and Flora and Fauna were considered demonetized after January 2, 1998.
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