First Lady Michelle Obama is promoting her new book "American Grown: The Story of the White House Kitchen Garden and Gardens Across America" and stopped by 'The Late Show With David Letterman' to present a new Top 10 list on the Fun Facts About Gardening.

Did you know that if you have an actual green thumb it might actually be scurvy? That's just one of the fun facts that Michelle Obama brought to David Letterman last night but that you probably won't find in her new book on the White House garden.

While she's ostensibly promoting her new book, she's also using the opportunity to parlay her popularity to help get her husband, Barack Obama, re-elected as president. In fact, President Obama makes a cameo of sorts at the end of Ms. Obama's list.

While she wasn't in New York City at the Ed Sullivan Theater, this is Ms. Obama's second appearance on 'The Late Show' after she appeared in person back in March. You can watch Michelle Obama's latest appearance with David Letterman below.