Wash the sorrel. Separate the sepals from the 'seed'. Wash the sorrel sepals again. Place in a deep pot and add the water, cinnamon, and optional spices.
Boil for about 20 minutes or until the sepals begin to lose their colour and look jelly-like. Strain the sorrel and allow to cool. After it cools, sweeten with sugar and add the rum if desired.
Transfer to a sterilized bottle and refrigerate. Serve chilled