Until 1997, when he represented Canada at the Venice Biennale with the film loop "Vexation Island", Graham was most well known for his series of photographs of Welsh oaks seen upside-down. For this project, he employed a photographer to take black and white negatives of majestic, isolated trees in the English countryside with a large-format camera. He then hung the pictures upside down, like camera obscura images. In 1998 Graham produced his definitive work on this theme, a series of seven monumental images of Welsh oaks printed on color paper to produce warm deep sepia and charcoal hues.