One of my favorite autumn things to do is shuffle through the leaves of every katsura tree I pass. What causes that enticing burnt sugar smell? Are there other trees that smell like this?
As the leaves of katsura trees (Cercidiphyllum japonicum) begin their process of decay, they are releasing molecules of maltol into the air and conjuring up scents reminiscent of toffee, cotton candy, or—as the German common name Kuchenbaum and the French arbre à caramel suggest–baking cake and caramel.
Maltol is also found in pine needles and lark barch, but it is most famously noticeable in katsura trees as they begin to turn color and the complex sugars in their leaves break down.