Most cooks–even unadventurous ones–can easily identify the yellowish-brown crescents known as fennel seeds. That’s because these tiny seeds, which actually represent the dried ripe fruits of the aromatic fennel plant (Foeniculum vulgare), have been handed down through the ages as a spice and food preservative. Their heady and memorable flavor, reminiscent of licorice and anise, is familiar to most people because fennel seeds are routinely used in rye bread.