L.C. of West Seattle asks:

Why do fennel and anise and licorice all taste sort of the same?

Dr. Food replies:

All plants with licoricelike aromas and flavors contain a small compound called trans-anethole. It looks like this:

Anise seeds are widely used in south and east Asian cooking; camphor gum, another powerful source of trans-anethole, has been used for thousands of years in folk medicine. Recently the pure compound has shown promise in treating certain kinds of cancer, so maybe the shamans were onto something. P.S. Our thanks to professor Joe Lefevre of the chemistry department at SUNY Oswego for his help with this one.