Did you ever wonder how Mr. Lemmon got its name? No, Mt. Lemmon is not named after a tree. It is spelled with two "M"s , not one.
Mt. Lemmon is named after botanist Sara Plummer Lemmon, wife of another botanist, John Lemmon. In the 1880's, few white people had ventured to the top of Mt. Lemmon. There were no roads. A man named E.O. Stratton, living on the north side, showed them the way. He became so impressed by Sara Lemmon that he pronounced the peak, Mt. Lemmon in her honor. In 1904, the name was recorded as such. There is a wonderful book on the human history of Mt. Lemmon. Read about it here.
Mt. Lemmon is known by another name, Babad Do'ag, or Frog Mountain to the Tohono O'odham, presumably because it has the appearance of a frog from a certain angle. I have yet to see it. Which name do you prefer?