By pure serendipity, five exhibitions this summer trace the interplay between canvas and nature—exotic, sun-dappled, manicured, and unspoiled. At Philadelphia's Pennsylvania Academy of the Fine Arts, "American Sublime" (June 15—Aug. 25) presents a rose-colored vision of our vast nation with more than 80 Hudson River school paintings. A world away from those panoramic vistas, New York's Metropolitan Museum complements a show of Gauguin's lost paradises with another of the meadows, forests, and mountains of Delacroix, Corot, and Cézanne, among others (June 18—Oct. 20, and June 18—Sept. 8, respectively). At the Clark Art Institute, in Williamstown, Massachusetts, the unfamiliar landscapes of Viennese Secessionist Gustav Klimt reveal how much he owed to Gauguin, van Gogh, and Japanese art (June 17—Sept. 2), while 60 atmospheric canvases by AbEx painter Joan Mitchell at New York's Whitney Museum connect the dots between Monet's water lilies and the New York school (June 20—Sept. 29).