Mike Sullivan is the author of The Trees of San Francisco, and has been sharing his tree expertise for years on his site sftrees.com. But he found new purpose during the pandemic, working with tree-loving friends to create chalk tree tours throughout the city. Total SF hosts Heather Knight and Peter Hartlaub sit down with Sullivan in his tree-filled Cole Valley backyard, and talk about S.F.'s good and bad tree neighborhoods, tree history and Peter's suggestion that there are "bad" trees. (Looking at you eucalyptus!) Also in this episode, the $1.7 million toilet limerick contest, with Sarah Katz-Hyman returning to help judge the entries. Produced by Peter Hartlaub. Music from the Sunset Shipwrecks off their album "Community," Castro Theatre organist David Hegarty and cable car bell-ringing by 8-time champion Byron Cobb. Follow Total SF adventures at www.sfchronicle.com/totalsf  Learn more about your ad choices. Visit megaphone.fm/adchoices