The 'grains' are actually seeds from large purple flowers that grow from tall bamboo-like stems with long pointed leaves, actually a relative of ginger. They are harvested in June or July at the time of heavy rains.
The dark brown seeds add a hot, spicy, peppery flavour plus hints of lavender, chocolate, citrus and elderflower to Bombay Sapphire. They highlight and accentuate the citrus in Bombay Sapphire and lengthen the finish.