When the tree reaches 110 to 120 years old (a mere teenager for a Ponderosa pine), it begins to shed its black bark and reveal an inner bark of yellow. There's something else that begins to happen to the tree in the "yellowbelly" phase. Stick your nose into a crevice of the bark and take a big sniff. It may smell like butterscotch or vanilla. The next person who smells it may insist it's more like cinnamon, or even coconut.
Scientists don't know why a closely sniffed Ponderosa smells like baking cookies. The aroma may arise from a chemical in the sap being warmed by the sun. (The Jeffrey pine, a close relative of the Ponderosa, is also known to turn yellow and give off a similar smell.)
And that, folks, is your factoid of the day. Brought to you by the letter P. for Punchy.