sentences:  During a brief period in the early 17th century, sassafras was the second-largest export from the British colonies in North America behind tobacco.Since the bark was the most commercially valued part of the sassafras plant due to large concentrations of the aromatic safrole oil, commercially valuable sassafras could only be gathered from each tree once.This meant that as significant amounts of sassafras bark were gathered, supplies quickly diminished and sassafras become more difficult to find.