Complex sentence: Sometimes these materials undergo a change during the course the their being exhibited-in "Red on Green" (1992), for example, ten thousand rose heads placed on a bed of their stalks gradually whithered as the exhibition went on.
Split into simpler sentences: Sometimes these materials undergo a change during the course the their being exhibited. In "Red on Green" (1992), ten thousand rose heads placed on a bed of their stalks gradually whithered as the exhibition went on.