Dutchman's Pipe Aristolochia macrophylla purple-greenDensely leafy and vigorous growing. That is the Dutchman's pipe (Aristolochia macrophylla). The large heart shaped green leaves stand out in the garden. Beautiful purple pipe shaped flowers appear in summer. Prune the Aristolochia in early spring. Prune weak shoots as close to the main stem as possible. Cut away stems that are too low. Cut the shoots on the main stem back to 3 buds. Place the base of the climbing plant in the sun. Place the runners in