The San Francisco artist Jonathon Keats is a master of delectably deadpan works. He has founded a pornographic theater for plants, screening grainy footage of pollination for an audience of titillated rhododendrons. He once mixed a ring tone based on John Cage’s silent composition, “4’33.” And he gave pencils and easels to Cypress trees so they could express themselves when the wind blew. “Everything I do comes out of practicality,” Keats says. The guy’s just trying to help out.