Like a tree pruned one too many times, some of the museum’s finest artworks have been forced to stay quiet. These are watercolors, pastels, gouaches, charcoals, and ink drawings that are rarely exhibited out of concern for their light-sensitive materials. But now special new lighting in Gallery 353 is allowing the museum to show these works more routinely. This selection pays tribute to trees, variously interpreted as dancing, frightening, chatty, wily, and close to perfection. Some works entered the collection only in the last several years, including mouthwatering watercolors by Auguste Lepère, Charles Burchfield, and Childe Hassam, and this delicate bit of poetry by the impressive Dutch landscapist Egbert van Drielst.