What are Coriander Seeds? Strangely, the leaf of the coriander plant, which we call cilantro, is generally described as spicy and herbaceous, yet the seed is one of the sweetest spices available. It has been said to have notes of white pepper and Navel orange, in addition to its sweet and floral aroma. It's been "cultivated," if you will, in both the literal and figurative aspects. Because of their delicious aroma and flavor, coriander seeds are a widely used spice in cuisines from Portugal to Mexico to India. Beers flavored with it have also gained in popularity. Use a simple syrup flavored with toasted coriander seed to create a sophisticated cocktail.