This Thursday night, November 20, University of Texas art historian Richard Shiff will unravel the moldy mysteries of Cy Twombly’s Untitled [A Painting in Nine Parts], AKA "The Green Paintings," just back from London, where they were part of "Cy Twombly: Cycles and Seasons," at the Tate Modern. 7 pm, free at the Menil Collection, Houston.