Did you you know? Dendrology, or the study of trees, has been used by art historians to help date many ancient paintings. Before canvas, paintings were most commonly painted on panels of wood, and are called panel paintings. Studying the rings in the wood and knowing when certain regional historical conditions such as draught caused abnormal rings, historians are often able to determine the age of the wood for a painting. With the advent of this technique, historians have sometimes found that famous paintings in museums have long been misdated.