The highest quality paper is that made from Broussonetia papyrifera, Edgeworthia papyrifera, and Wikstroemia sikikiana. The Japanese make use of these three kinds of tree bark as the major material to make their celebrated washi paper.
在台灣，手工紙原料除了量多、取得容易的竹、草類外，樹皮亦是重要材料。如果就高級特用紙張而言，樹皮類中又以構樹、三椏，和雁皮的品質最佳，日本著名的「和紙」即是以這三類樹皮為主。